SERVICE MANUAL

TRUCK SERVICE MANUAL

ELECTRICAL SYSTEM TROUBLESHOOTING GUIDE — 5000i and 9000i

Model: 5000i
Start Date: 05/01/1999
Model: 9100i
Start Date: 05/01/1999
Model: 9200i
Start Date: 05/01/1999
Model: 9400i
Start Date: 05/01/1999
Model: 9900i
Start Date: 05/01/1999

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06/26/2002

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Copyright © 06/26/2002 International Truck and Engine Corporation
 TRUCK SERVICE MANUAL i

Table of Contents

INTRODUCTION. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .1

SAFETY INFORMATION.. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .2

GROUP 08 ELECTRICAL.. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . ..3

1 POWER DISTRIBUTION AND GROUND SYSTEM. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .3
2 CAB ACCESSORIES. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . .19
3 BATTERY, CHARGING AND CRANKING SYSTEMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111
4 ELECTRICAL TROUBLESHOOTING ETHER START. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
5 ELECTRICAL TROUBLESHOOTING FANS. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .151
6 CATERPILLAR C-10, C-12 AND 3406E ENGINES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .185
7 DETROIT DIESEL SERIES 60 ENGINES. . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .227
8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .265
9 CUMMINS ISM AND AHD ENGINE SYSTEM. . . . . . . . .. . . . . . . . . .. . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . .319
10 INTERNATIONAL 530E I6 HEUI ENGINES.. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. .371
11 CHASSIS ACCESSORIES. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .407
12 LIGHT SYSTEMS. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .433
13 SLEEPER LIGHTING AND ACCESSORIES . . . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . . .. . .509
14 HEATER AND AIR CONDITIONER. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .559

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 TRUCK SERVICE MANUAL 1

INTRODUCTION
Use with Circuit Diagram Book CTS-5298 or S08225.

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SAFETY INFORMATION
IMPORTANT – Read the following before starting the service procedure.

The information contained in this International Service Manual Section was current at the time of printing
and is subject to change without notice or liability.

You must follow your company safety procedures when you service or repair equipment. Be sure to understand
all of the procedures and instructions before you begin work on the unit.

International uses the following types of notations to give warning of possible safety problems and to give
information that will prevent damage to the equipment being serviced or repaired.

WARNING – A warning indicates procedures that must be followed exactly. Personal injury
or possible death can occur if the procedure is not followed.

CAUTION – A caution indicates procedures that must be followed exactly. If the procedure is not
followed, damage to equipment or components can occur.

NOTE – A note indicates an operation, procedure or instruction that is important for correct service.

Some procedures require the use of special tools for safe and correct service. Failure to use these special
tools when required can cause injury to service personnel or damage to vehicle components.

This service manual section is intended for use by professional technicians, NOT a “do-it-yourselfer.” It is
written to inform these technicians of conditions that may occur on some vehicles, or to provide information
that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools,
safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume
that the service section applies to your vehicle. See your International Truck Dealer for information on whether
this service section applies to your vehicle.

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Group ELECTRICAL
Table of Contents

1. DESCRIPTION. .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ..5
1.1. POWER DISTRIBUTION SYSTEM. .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . ..5
1.2. GROUND SYSTEM. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . ..5

2. OPERATION.. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .5
2.1. COMMON SYSTEM COMPONENTS. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . .. . .. .. . .5
Fuses And Circuit Breakers. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .5
Junction Adapters And Studs. .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . ..5
Relays And Solenoids. . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . . .. .6
2.2. BATTERY POWER DISTRIBUTION (WITHOUT 3+1 BATTERY SYSTEM). . . . . . . . . . . . . . . . . . . . . . . . .6
2.3. IGNITION POWER.. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .6
2.4. ACCESSORY POWER. .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . ..6
2.5. START POWER.. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . ..6
2.6. VEHICLE GROUND SYSTEM.. .. . .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. . .6
2.7. 3+1 BATTERY SYSTEM. . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . . ..6
Engine Running Mode. . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . ..7
Engine OFF Mode.. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .7

3. TROUBLESHOOTING. .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . ..7
3.1. GENERAL TROUBLESHOOTING. .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .7
3.2. TESTING 3 +1 BATTERY SYSTEM. .. . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . . . . . .. . .8
3.3. TESTING IGNITION POWER DISTRIBUTION SYSTEM. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .9

4. COMPONENT LOCATIONS. .. .. . .. . .. .. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .9

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1. DESCRIPTION
1.1. POWER DISTRIBUTION SYSTEM
The power distribution system provides power to the key switch, the starter solenoid, and the (B1) and (B2)
battery studs. The 150 amp. megafuse, which must be replaced when blown, supplies power to the (B1) and
(B2) battery studs. Power from the (B1) and (B2) battery studs is then distributed to the fuse block and
individual fused circuits. Fuse F7-A is located in the feed circuit for the key switch and provides protection
for the key switch and any unfused circuits attached to the key switch.

1.2. GROUND SYSTEM

The ground system provides a power return path to the vehicle batteries. Included in this system are ground
straps that connect the cab, engine and frame to the negative battery terminals.

2. OPERATION
Refer to the 12V POWER DISTRIBUTION circuit diagrams in CTS-5298 or S08225.

2.1. COMMON SYSTEM COMPONENTS

Fuses And Circuit Breakers

CAUTION – Never replace a fuse or circuit breaker with a higher load rated fuse or circuit breaker.

Fuses are standard (Type III circuit breakers are optional), except for headlights and windshield wipers, which
have Type I circuit breakers.

Most of the fuses and/or circuit breakers are located in the Power Distribution panel in the cab. The Power
Distribution panel cover contains a listing of installed circuit protection devices, size and location.

1. Type III Circuit Breakers

Type III circuit breakers open if current flow exceeds the rated capacity and can be reset by depressing the
reset button on the breaker after the overload condition has been removed.

2. Type I Circuit Breakers

Type I circuit breakers (headlights and windshield wipers) reset automatically. However, if the excessive
current flow condition causing the breaker to open is not corrected, the circuit breaker will reopen and
remain open until the winding cools, then automatically reset. With an overload condition present, the
circuit breaker will cycle (open and close) until the condition is corrected. The circuit breaker will become
hot to the touch.

NOTE – Type I circuit beakers must only be replaced with approved Navistar Type I circuit breakers.

Junction Adapters And Studs

In the circuit diagrams, bussed adapters and studs are most often, but not always, given a name such as (B2)
Battery Adapter (498), etc. These junction connections can be either feeds or grounds and are identified as

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such. The bus adapters have a common feed or ground and the other terminals are connected internally by
a bus bar.

Relays And Solenoids

Relays and solenoids are switching devices. International uses only suppressed relays and solenoids to
prevent voltage spikes from damaging electronic components in the vehicle electrical system. Once a
transistor has been "spiked," it may not fail immediately, but its life will be shortened.

Note that relays used inside the cab are not sealed, but relays in less protected areas, such as the engine
compartment, are sealed for longer life.

NOTE – Only replace relays and solenoids with correct International parts.

2.2. BATTERY POWER DISTRIBUTION (WITHOUT 3+1 BATTERY SYSTEM)

With the ignition key switch in the off position, the batteries provide power to the (B1) and (B2) battery studs,
through the 150 amp. megafuse. From the (B1) and (B2) battery studs power is distributed to selected
electrical systems.

With 3+1 System, refer to 3+1 Battery System below.

2.3. IGNITION POWER

Battery power from the (B1) battery stud is applied to the common terminal (30) of the ignition relay (462)/R1
and to the key switch "B" terminal. With the key switch in the on position, power from the key switch "I" terminal
energizes the ignition relay, applying power to the ignition adapters and fuses. With the key switch in the start
or ignition position, power is present at the "I" terminal.

2.4. ACCESSORY POWER

Battery power from the (B1) battery stud is applied to the common terminal (30) of the accessory relay (145)
and to the key switch "B" terminal. With the key switch in the ACC position (or IGN position), power from the
key switch "A" terminal:

A. Energizes the accessory adapter relay (145), applying power to A3 accessory adapter (501).
B. Flows to A1 Accessory Adapter (499) and to the Electric Wiper Intermittent Relay.

2.5. START POWER

With the key switch in the start position, battery power from (B1) battery stud is applied through the key switch
"S" and "I" terminals to the start circuits.

2.6. VEHICLE GROUND SYSTEM

The engine, frame, cab and negative battery terminals are electrically connected by ground cables, which
provide common ground points (studs or ground adapters).

2.7. 3+1 BATTERY SYSTEM

The 3+1 battery system includes three cranking batteries and one deep cycle battery. The purpose of this
system is to prevent discharging the three cranking batteries while operating certain electrical accessories
connected to (B2), off the fourth battery, when the engine is not running.

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Engine Running Mode

With the engine running, power (7 volts) from the alternator “R” terminal energizes the isolated battery magnetic
switch, closing the contacts. This links the positive terminal of the deep cycle and cranking motor batteries,
recharging all four batteries and supplying power from all four batteries to both the (B1) and (B2) battery studs.

Engine OFF Mode

The deep cycle battery supplies power to components receiving power from the (B2) battery stud.

The three cranking batteries supply power to the components receiving power from the (B1) stud.

3. TROUBLESHOOTING
Refer to the 12V POWER DISTRIBUTION circuit diagrams in CTS-5298 or S08225.

A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 -
ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not
covered in detail. It is assumed that the technician knows to check for a malfunctioning switch,
relay, or solenoid.

3.1. GENERAL TROUBLESHOOTING

If more than one electrical circuit is not working, a good place to begin troubleshooting is with the power and
ground distribution diagrams. Refer to 12V POWER DISTRIBUTION, GROUND ADAPTER COMPOSITE
and GROUND STUD COMPOSITE circuit diagrams in CTS-5298 or S08225 for ground composites. Look for
common power sources, common grounds, common fuses, etc. In the event that several circuits malfunction,
check common feeds and ground first as they are likely the problem.

If this does not assist in correcting the problem, proceed to the section(s) that provide detailed troubleshooting
guide for the specific circuits.

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3.2. TESTING 3 +1 BATTERY SYSTEM

Table 1 Testing 3+1 Battery System
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off At 7V isolated battery 7V mag <1 ohm. Go to next Locate open or
magnetic switch, switch, 11H step. poor connection in
measure resistance to gnd. circuit 11H, then
from circuit 11H to repair.
ground.
2. Off At mag. switch and Mag. sw., 1/0 12± 1.5 volts. Go to next Locate cause of
1/0 red cable, measure red cable to step. low or no voltage
voltage to gnd. gnd. in 1/0 red cable,
then repair.
3. Off At mag. switch and 1/0 Mag. sw., Approx. 12 Go to next Locate cause of
black wire, measure black wire to volts (same step. no or low voltage
voltage to gnd. gnd. as deep cycle in 1/0 black wire,
battery.) then repair.
4. Off Measure voltage Across mag. Less than or Go to Step Go to next step.
across large terminals sw. greater than 7.
of the mag. switch. 0 volts.
5. On Start engine and at Mag. sw., 7 Approx. Go to next Locate cause of
7V isolated battery to gnd. 7 volts step. low or no voltage
magnetic switch, (pulsating in circuit 7, then
measure voltage from DC). repair.
circuit 7 to gnd.
6. Off Remove battery cables Mag. sw., >100K ohms. Go to next Replace mag.
and at 7V mag. switch, across large step. switch; it is not
measure resistance term. opening the circuit.
across large terminals.
7. Off/ On Reconnect any Mag. sw., 0 volts. Go to next Turn off key
disconnected circuits across large step. switch, disconnect
and start vehicle. term. battery cables, and
Measure voltage replace defective
across large terminals magnetic switch.
of 7V mag. switch.
8. Off Check voltage to (B2) to gnd. 12± 1.5 volts. 3+1 Locate cause of
ground at (B2) battery battery low or no voltage in
stud. circuits fusible link 14-FL,
check circuit 14A or
good. 14AB, then repair.

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3.3. TESTING IGNITION POWER DISTRIBUTION SYSTEM

Table 2 Testing Ignition Power Distribution System
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Check fuses F2-C F2-C and <1 ohm. Go to next Locate cause
and F7-A for open F7-A. step. of overload
condition. condition, then
repair. Replace
the fuse(s).
2. Off/ On Remove ignition relay (462-R1), 12± 1.5 Go to next Locate cause of
(462-R1). Turn key 14S and 13A volts. step. low or no voltage,
on. At conn. (462-R1) to gnd. then repair.
measure voltage to
ground at circuits 14S
and 13A.
3. On At conn. (462-R1) (462-R1) 12± 1.5 Go to next Locate open or
measure voltage between 14S volts. step. poor connection
between circuits 14S and 13-GA. in circuit 13-GA
and 13-GA. to ground, then
repair.
4. Off Measure resistance Between <5 ohms. Go to next Locate open or
between circuit conn. step. poor connection
13H/13P between (462-R1) in circuit 13H/13,
conn. (462-R1) and & ignition then repair.
ignition adapter (495). adapter
(495).
5. Off/ On Re-install relay at (495), 13P to 12± 1.5 Go to next Replace the relay.
conn. (462-R1). Turn gnd. volts. step.
key on. At adapter
(495) circuit 13P,
measure voltage to
gnd.
6. On Measure voltage from 13H to gnd. 12± 1.5 Go to next Locate cause of
circuit 13H to ground volts. step. low or no voltage
(at connection to fuse in circuit 13H, then
F4-C). repair.
7. On Measure voltage from 13F to gnd. 12± 1.5 Ignition Locate cause of
circuit 13F to ground volts. power low or no voltage
[at connection to system in circuit 13F, then
adapter (494)]. checks good. repair.

4. COMPONENT LOCATIONS
(B1) Battery Stud. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . . Power Distribution Panel
(B2) Battery Stud. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . . Power Distribution Panel
(1) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Left Side of Engine Cowl
(2) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Above Conn. 3
(3) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Below Conn. 2

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(40) Key Switch. .. . .. .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . ... . . . . . Behind Left Side of Instrument Panel

(41) Push Button Start Switch. . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Center of Instrument Panel
(149) Accessory Adapter Relay.. .. . .. .. . .. .. . .. . .. ... . . . . . Power Distribution Panel
(425) Panel Light Switch.. .. .. .. .. .. .. .. .. .. .. .. .. .. ... . . . . . At Switch Cluster
(453) Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Center of Dash Behind Wing Panel
(454) G2 Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(455) G3 Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(456) G4 Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Center Instrument Panel
(462) R1 Ignition Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(494) I1 Ignition Adapter. .. . . . .. . . . .. . . . .. . . . .. . . . .. . .. . . . . . Behind Fuse Panel
(495) I2 Ignition Adapter. .. . . . .. . . . .. . . . .. . . . .. . . . .. . .. . . . . . Behind Fuse Panel
(497) B1 Battery Adapter. .. . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . Behind Fuse Panel
(498) B2 Battery Adapter. .. . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . Behind Fuse Panel
(499) A1 Accessory Adapter. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel Right Side
(501) A3 Accessory Adapter. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel Right Side
(503) L1 Panel Light Feed Adapter. .. . .. . .. . .. . .. . ... . . . . . Behind Lt Instrument Panel
(504) L2 Panel Light Feed Adapter. .. . .. . .. . .. . .. . ... . . . . . Behind Instrument Panel/Switch Breakout
(506) L4 Panel Light Gnd Adapter.. . .. . . .. . .. . .. . . ... . . . . . At Right of Instrument Panel
(509) Start Feed Adapter. .. . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . 6 Inches Left of Fuse Panel Near Heater Controls

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Figure 1 Cab Wiring (Dash)

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1. 150A MEGAFUSE
2. TO (B1) BATTERY STUD
3. START MAG SWITCH
4. NO BUS BAR WITH 3+1 BATTERY SYSTEM
5. TO HEATER
6. (3) ENGINE HARNESS CONNECTOR
7. (2) CHASSIS HARNESS CONNECTOR
8. RIGHT HAND DASH GROUND STUD
9. FUSE BLOCK GROUND STUD
10. (B2) BATTERY STUD
11. (B1) BATTERY STUD
12. KEY SWITCH
13. LEFT HAND DASH GROUND STUD
14. (1) FRONT END HARNESS CONNECTOR
15. GROUND CIRCUITS
16. DASH PANEL

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Figure 2 Cab Wiring (Power Distribution Center/Fuse Panel) (B1) and (B2) Battery Stud
1. CIRCUIT 14A FROM START MAG SWITCH
2. 3+1 CAB HARNESS CONNECTS TO 3+1 ENGINE HARNESS
3. CIRCUIT 14A FROM 3+1 MAG SWITCH

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Figure 3 Isolated Battery Wiring (Typical)

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1. 3+1 BATTERY SYSTEM HARNESS

2. SEE FIGURE 4
3. SEE VIEW BELOW
4. CIR 14A
5. TO B2 BATTERY STUD
6. CIRCUIT 7
7. CIRCUIT 7
8. SEE VIEW ABOVE
9. 3+1 BATTERY SYSTEM HARNESS

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Figure 4 Isolated Battery Wiring (Typical)

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1. DEEP CYCLE BATTERY

2. RED CABLE TO 7V MAGNETIC SWITCH
3. CRANKING BATTERY
4. GROUND
5. CIRCUITS 4A & 7
6. SEE FIGURE 3
7. 3+1 BATTERY SYSTEM HARNESS
8. MAGNETIC SWITCH WITH 3+1 SYSTEM
9. CIRCUIT 11H, 7V MAGNETIC SWITCH
10. CRANKING BATTERY
11. CIRCUIT 11H
12. RED CABLE
13. 7V ISOLATED BATTERY MAGNETIC SWITCH
14. CIRCUIT 14FL
15. CIRCUIT 7
16. BLACK CABLE
17. CRANKING BATTERY
18. BATTERY BOX

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Table of Contents

1. DESCRIPTION.. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. ..21
1.1. CIGAR LIGHTER (CAB).. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . ..21
1.2. CLOCK (CAB).. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. .21
1.3. ELECTRIC WINDOW - RIGHT. .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . ..21
1.4. ELECTRIC WINDOW - RIGHT AND LEFT. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. .21
1.5. DEFROSTER FANS. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . ..21
1.6. ELECTRIC WINDSHIELD WIPERS — INTERMITTENT WIPE AND WASH. . . . . . . . . . . . . . . . . . . . . . .21
1.7. ELECTRIC HORN. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. .21
1.8. MIRRORS - HEATED AND LIGHTED.. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. . .. .. .. ..21
1.9. MIRRORS - MOTORIZED. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . .21
1.10. C.B. RADIO CAB POWER SOURCE. .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. ..21
1.11. C.B. RADIO ACCOMMODATION PACKAGE. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .22
1.12. CAB RADIO AND SPEAKERS.. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . ..22
1.13. OWNER/OPERATOR SPARE SWITCH. .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. .22
1.14. ELECTRIC LOCK - RIGHT AND LEFT.. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. ..22
1.15. INTERVISION DISPLAY. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. ..22
1.16. EATON VORAD COLLISION AVOIDANCE EVT-300. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. ..22
1.17. TEMPERATURE/COMPASS DISPLAY.. .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. ..22
1.18. ROAD RELAY IV.. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .. .22
1.19. HEATED SEAT-DRIVER.. . . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . .22
1.20. HEATED SEAT-PASSENGER.. . . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. .22

2. OPERATION. .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. .22
2.1. CIGAR LIGHTER (CAB).. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . ..23
2.2. CLOCK (CAB).. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. .23
2.3. ELECTRIC WINDOW - RIGHT (ONLY). .. . . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . .23
Window Down Operation. . . . . . .. . . . . . . . . .. . . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . . . .. . . . . .23
Window Up Operation. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. .23
2.4. ELECTRIC WINDOW - RIGHT AND LEFT. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. .23
Right Window Down Operation. .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . . .. . .. .23
Right Window Up Operation. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. ..24
Left Window Down Operation.. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .24
Left Window Up Operation.. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. ..24
2.5. DEFROSTER FANS. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . ..24
2.6. ELECTRIC WINDSHIELD WIPERS - INTERMITTENT WIPE AND WASH. .. . .. . .. . .. . .. . .. . .. . .. .24
Two Speed Wiper With Intermittent Wiper And Washer Operation. . . . .. . . . . . . .. . . . . . . .. . . . .24
2.7. ELECTRIC HORN. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. .26
2.8. MIRRORS - HEATED AND LIGHTED.. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. . .. .. .. ..26
2.9. MIRRORS - MOTORIZED. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . .26
2.10. C.B. RADIO CAB POWER SOURCE. .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. ..26
2.11. C.B. RADIO ACCOMMODATION PACKAGE. . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .26
2.12. CAB RADIO AND SPEAKERS.. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . ..26
2.13. OWNER/OPERATOR SPARE SWITCH. .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. .27
With Fuse. .. . . .. . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. .27
Without Fuse.. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. .27
2.14. ELECTRIC LOCK - RIGHT AND LEFT.. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. ..27
2.15. INTERVISION DISPLAY. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. ..27

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2.16. EATON VORAD COLLISION AVOIDANCE EVT-300.. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .27

2.17. TEMPERATURE/COMPASS DISPLAY. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .27
2.18. ROAD RELAY IV. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .28
2.19. HEATED SEAT-DRIVER. . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . . ..28
2.20. HEATED SEAT-PASSENGER. . .. . .. . . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . .28

3. TROUBLESHOOTING. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .28
3.1. TESTING CIGAR LIGHTER (CAB). .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .28
3.2. TESTING CLOCK (CAB). . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .29
3.3. TESTING ELECTRIC WINDOW - RIGHT.. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .30
3.4. TESTING ELECTRIC WINDOW - RIGHT AND LEFT. .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .32
3.5. TESTING DEFROSTER FAN(S).. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .37
3.6. TESTING WINDSHIELD WIPER AND WASHER SYSTEM. . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . .38
3.7. TESTING ELECTRIC HORN. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .42
3.8. HEATED AND LIGHTED MIRRORS. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . ..43
Testing Heated Mirrors. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . ..43
Testing Mirror Lights. . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. .44
3.9. MOTORIZED MIRRORS.. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .45
Testing Right Motorized Mirror. . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . .45
Testing Dual Axis Motorized Mirrors.. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .47
3.10. TESTING CB POWER SOURCE. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .49
3.11. TESTING RADIO-CB ACCOMMODATION PACKAGE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50
3.12. TESTING RADIO-CAB SPEAKERS.. .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .51
3.13. TESTING OWNER/OPERATOR SPARE SWITCH (FUSED). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
3.14. TESTING OWNER/OPERATOR SPARE SWITCH (NON-FUSED). . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .55
3.15. TESTING ELECTRIC LOCK – RIGHT AND LEFT. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .56
3.16. TESTING INTERVISION CIRCUITS. . . .. . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . ..59
3.17. TESTING EATON VORAD COLLISION AVOIDANCE EVT-300 CIRCUITS. . . . . . . . . . . . . . . . . . . . . .61
3.18. TESTING TEMPERATURE/COMPASS DISPLAY CIRCUITS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63
3.19. TESTING ROAD RELAY IV CIRCUITS. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .64
3.20. TESTING HEATED SEAT-DRIVER. . . . .. . . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . ..65
3.21. TESTING HEATED SEAT-PASSENGER. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .66

4. COMPONENT LOCATIONS.. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . .. . . . ..67

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1. DESCRIPTION
1.1. CIGAR LIGHTER (CAB)
The Cigar Lighter circuit provides power to the Cigar Lighter or other item plugged into the lighter socket. The
socket is located to the right of the driver at the base of the wing panel.

1.2. CLOCK (CAB)

The Clock circuit provides power to an optional analog clock. The clock is located to the right of the driver in
one of the four optional gauge openings of the wing panel.

1.3. ELECTRIC WINDOW - RIGHT

The right side electric window provides a means for the driver to operate the passenger’s side window from
the driver’s seat.

1.4. ELECTRIC WINDOW - RIGHT AND LEFT

The right and left side electric window provides a means for the driver to operate both the driver’s and
passenger’s side window from the driver’s seat. It also allows the passenger to control the passenger’s
side window.

1.5. DEFROSTER FANS

The single defroster or dual defroster options provide an increase in airflow over the windshield.

1.6. ELECTRIC WINDSHIELD WIPERS — INTERMITTENT WIPE AND WASH

Electric windshield wipers have a two-speed motor and intermittent wipe and wash feature, and are self
parking when they are turned off.

1.7. ELECTRIC HORN

The electric horn is located in the grille of the truck and provides a means of signaling or warning other
vehicle drivers.

1.8. MIRRORS - HEATED AND LIGHTED

Optional heated and lighted mirrors are available for the left and right side.

1.9. MIRRORS - MOTORIZED

Optional motorized right mirror, or dual axis motorized mirrors are available.

1.10. C.B. RADIO CAB POWER SOURCE

An optional Citizens Band radio power source is available in two styles. One style is the traditional cigar
lighter socket, and the other is the terminal block style.

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1.11. C.B. RADIO ACCOMMODATION PACKAGE

An optional Citizens Band radio accommodation package is available that provides a speaker, and speaker
and power connections.

1.12. CAB RADIO AND SPEAKERS

An optional radio and front and rear speaker package is available. For tractors with a sleeper, speakers
are also available.

1.13. OWNER/OPERATOR SPARE SWITCH

An optional owner/operator spare switch is available. Two different styles are available: one with a fused relay
circuit, and one with a plain toggle switch.

1.14. ELECTRIC LOCK - RIGHT AND LEFT

Power locks, with controls in the driver and passenger doors, will lock or unlock all doors.

1.15. INTERVISION DISPLAY

The Intervision display is an optional electronic interface which displays vehicle information for drivers, fleet
managers and service technicians.

1.16. EATON VORAD COLLISION AVOIDANCE EVT-300

The EATON VORAD Collision Avoidance EVT-300 is an optional computerized collision warning system that
uses forward-looking mounted radar and optional side-looking radar to constantly monitor vehicles ahead and
in blind spot area, respectively.

1.17. TEMPERATURE/COMPASS DISPLAY

The optional temperature and compass display provides the driver with outside temperature and compass
directions.

1.18. ROAD RELAY IV

The optional Cummins road relay IV provides the driver with an electronic engine monitoring and driver display
system. The driver display module is mounted in driver side cutout of header panel.

1.19. HEATED SEAT-DRIVER

Optional heated seat is available for the driver.

1.20. HEATED SEAT-PASSENGER

Optional heated seat is available for the passenger.

2. OPERATION
Refer to CAB ACCESSORIES circuit diagrams in CTS-5298 or S08225.

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2.1. CIGAR LIGHTER (CAB)

The cigar lighter receives power from 15A fuse F2-A with the key on or off. The cigar lighter is grounded at
the left dash panel ground stud.

2.2. CLOCK (CAB)

The analog clock receives power from 10A fuse F10-A, with the key on or off. The clock is grounded through
ground adapter (454).

2.3. ELECTRIC WINDOW - RIGHT (ONLY)

The right side electric window is controlled by the driver’s right side window switch. To operate the window, the
key must be in the on or accessory position. The circuit includes the electric window relay (1159), window
switch (1158) and the right window motor. Power to the window switch is supplied from the B1 battery stud to
the common terminal (30) of the window relay (1159). With the key in the on or accessory position, the relay is
energized applying power to terminal 4 (and internally to terminal 3) at the electric window switch (1158). Note
that switch terminals 4 and 3 are at 12V with key on and terminals 1 and 6 are always at ground.

Window Down Operation

With the window switch in the down position, power from switch terminal 5 is applied to the motor on circuit
83L. Circuit 83M from the motor to the switch terminal 2 becomes the ground circuit. With the switch in the
down position, switch terminals 2 and 1 are connected, completing the path to ground.

Window Up Operation

With the window switch in the up position, power from switch terminal 2 is applied to the motor on circuit 83M.
Circuit 83L from the motor to the switch terminal 5 becomes the ground circuit. With the switch in the up
position, switch terminals 5 and 6 are connected, completing the path to ground.

2.4. ELECTRIC WINDOW - RIGHT AND LEFT

The right and left side electric windows are controlled by the driver’s right and left side window switches. The
passenger can also control the Right side window. To operate the windows, the key must be in the on or
accessory position. The circuit includes the electric window relay (1138), driver’s side right window switch
(1040), driver’s side left window switch (1039), passenger’s side window switch (1041), the right window motor
and the left window motor. Power to the three window switches is supplied from the B1 battery stud to the
common terminal (30) of the window relay (1138). With the key in the on or accessory position, the relay is
energized applying power to terminal 4 (and internally to terminal 3) of the driver side right and passenger side
window switches (1040) and (1041). The window relay also supplies power to the driver side left switch on
terminal 28 and internally to terminal 1.

Right Window Down Operation

With the passenger’s side switch (1041) in the neutral position and the driver’s side right window switch (1040)
in the down position, power from switch terminal 5B is applied to the motor on circuit 83J through terminals 6
and 5B of switch (1041) to circuit 83M. Circuit 83L from the motor, through switch (1041) terminals 2B and 1,
circuit 83K to switch (1040) terminal 2B becomes the ground circuit.

With the passenger’s side switch in the down position, power from terminal 5B is applied to circuit 83M. Ground
is supplied on circuit 83L through switch (1033), circuit 83K, and switch (1040) from circuit 83-GB.

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Right Window Up Operation

With the passenger’s side switch (1041) in the neutral position and the driver’s side right window switch (1040)
in the up position, power from switch terminal 2B is applied to the motor on circuit 83K through terminals 1
and 2B of switch (1041) to circuit 83L. Circuit 83M from the motor, through switch (1041) terminals 5B and 6,
circuit 83J to switch (1040) terminal 5B becomes the ground circuit.

With the passenger’s side switch in the up position power from terminal 2B is applied to circuit 83L. Ground is
supplied on circuit 83M through switch (1033), circuit 83J, and switch (1040) from circuit 83-GB.

Left Window Down Operation

With the window switch in the down position, power from switch terminal 4 is applied to the motor on circuit
83N. Circuit 83F from the motor to the switch terminal 1 becomes the ground circuit. With the switch in the
down position, switch terminals 2B and 1 are connected, completing the path to ground.

Left Window Up Operation

With the window switch in the up position, power from switch terminal 1 is applied to the motor on circuit 83F.
Circuit 83N from the motor to the switch terminal 4 becomes the ground circuit. With the switch in the up
position, switch terminals 2B and 4 are connected, completing the path to ground.

2.5. DEFROSTER FANS

Power for the defroster fan(s) is supplied from fuse F5–B on circuits 86E and 78F to connector (313). When
the defroster switch is in the high position, power from connector (313) flows through the switch to the high
speed windings of the defroster motor(s). When the defroster switch is in the low position, power from
connector (313) flows through the switch to the low speed windings of the defroster motor(s). Ground for the
motors is provided on circuits 11–GB, 11–GAB, 11–GAC and 76–G.

2.6. ELECTRIC WINDSHIELD WIPERS - INTERMITTENT WIPE AND WASH

Two Speed Wiper With Intermittent Wiper And Washer Operation

Table 3 Wiper Washer Switch Operation

SWITCH MOTION FUNCTION
Top Toggle In If wiper is off, Turns wiper to low speed. If wiper is on in any mode,
(ON/OFF) turns wiper off.
Up If wiper is off, turns wiper on to high speed.

If wiper is on, Increments wiper to next highest speed.

If held more than one second wiper speed increases directly to high.
Down If wiper is off, turns wiper on to low speed.

If wiper is on, Increments wiper to next lowest speed.

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Table 3 Wiper Washer Switch Operation (cont.)

If held more than one second wiper enters it’s longest delay mode.
Bottom Button In If pressed less than 1/2 second, wiper performs a single lowspeed dry
(WASH) wipe (mist function).

If pressed and held more than 1/2 second, wiper continues in low speed
and washes for 2 seconds or until released (whichever occurs later).

After release wiper continues to cycle in low speed for 3 seconds, then
wiper returns to previous state.

The electric windshield wiper with intermittent wipe and wash switch (1171) is an electronic device which
controls the wiper relays and the washer pump depending on how the switch and washer button are pressed.

Ignition switched power — With the ignition switch on power from 10 amp fuse F10-B is applied to wiper-low
speed delay relay (143) terminal 86, wiper-high speed delay relay (143) terminal 86, and windshield washer
w/wiper delay switch (1171) terminal 1.

Battery power — Battery power from 15 amp fuse F4-D is applied to wiper-high speed delay relay (143)
terminal 30, windshield washer pump (9) on circuit 87B, and windshield wiper motor connector (430) terminal A.

Low Speed Wiper Operation — When the wiper switch selects low wiper speed, a ground from the wiper
switch (1171) terminal 3 is applied to wiper- low speed relay (143) terminal 85. This energizes the relay
applying 12 volts from the closed contacts of high – speed relay (142) terminal 87 to the low speed winding of
the wiper motor through connector (430) terminal D.

High Speed Wiper Operation — When the wiper switch selects high wiper speed, a ground from the wiper
switch (1171) terminal 4 is applied to wiper- high speed relay (142) terminal 85. This energizes the relay
applying 12 volts from terminal 87 to the high speed winding of the wiper motor through connector (430)
terminal E.

The wiper switch also energizes the low speed relay (143), with a ground on circuit 82B, to open the park
circuits and prevent 12 volts from being applied to the low speed winding of the wiper motor.

Park Operation — Note that power is always present at the P terminal of the crank motor. When the wipers
are turned off and the wiper blades are not parked, the circuit between wiper motor P and S is closed. In this
position, power at P goes through the contacts and out S, through the normally closed contacts of the wiper
relay (143) and back to the low speed winding of the wiper motor. The motor continues to operate until the
park switch rotates, opening the circuit between terminal S and P, and closing the circuit between S and X,
parking the wipers and turning off operation.

Windshield Washer Operation — When the wiper switch selects the windshield washer, ground from switch
(1171) is applied from terminal 5 to circuit 87A of the washer pump motor.

Intermittent Wiper/Wash Operation — The electronic wiper switch (1171) controls the washer and the low
and high speed wiper circuits to perform intermittent wiping and washing as requested.

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26 2 CAB ACCESSORIES

2.7. ELECTRIC HORN

Battery power from 15A fuse F5-C is always available to the horn relay (463)/R7 at the common terminal (30)
and control coil (86). Depressing the horn closes the relay ground circuit energizing the relay and applying
power to the horn.

2.8. MIRRORS - HEATED AND LIGHTED

Heated Mirror — With the key in the on or accessory position, the heated mirror elements receive power from
the ignition relay (462–R1) through 10A fuse F5-A.

Mirror Lights — Power to the mirror lights is controlled by the cab and trailer lights relay (464–R9). Refer to
LIGHT SYSTEMS for that system. Power from cab and trailer lights relay (464–R9) is applied to 15A fuse
F8-C, which supplies power to operate the mirror lights.

2.9. MIRRORS - MOTORIZED

Right Motorized Mirror — The right motorized mirror switch (437) receives power from ignition relay
(462–R1), through 10A fuse F5-A, when the key is in the on or accessory position. Momentarily positioning the
switch down from the neutral position closes the circuit between switch contacts 1 - 2 and 4 - 5. This applies
voltage to the motor on circuit 78F and grounds the motor through 78E. Momentarily positioning the switch up
from the neutral position closes the circuit between switch contacts 2–3 and 5–6. This applies voltage to the
motor on circuit 78E and grounds the motor through 78F.

Dual Axis Motorized Mirrors — The dual axis motorized mirror switch 1137 receives power from ignition
relay (462–R1), through 10A fuse F5–A, on circuit 78C, through connector (1137), when the key is in the
on or accessory position. Twisting the mirror control switch knob selects which mirror will be controlled.
Positioning the L/R switch to the Left or Right position will cause the controlled mirror to move to the Left or
Right. Positioning the U/D switch to the Up or Down position will cause the controlled mirror to move Up or
Down. Ground for the circuits is supplied from GND Adapter (456) on circuit 78–GA through connector (1137).

Use the DUAL AXIS MOTORIZED MIRROR circuit diagrams in CTS-5298 or S08225 to determine which
circuits are energized to move the mirrors.

2.10. C.B. RADIO CAB POWER SOURCE

Battery power from (B2) battery stud supplies power to the CB radio power receptacle. The circuit is protected
by 20A fuse F5-D.

2.11. C.B. RADIO ACCOMMODATION PACKAGE

This option provides an accessory power CB radio connection. The circuit is protected by 10A fuse F5–B and
the connection is grounded through the right dash ground stud. An external speaker is also provided.

2.12. CAB RADIO AND SPEAKERS

Refer to the RADIO — CAB SPEAKERS circuit diagrams in CTS-5298 or S08225 for radio and speaker
installation.

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 2 CAB ACCESSORIES 27

2.13. OWNER/OPERATOR SPARE SWITCH

With Fuse

This option provides switched battery power on circuit 14AQ for owner/operator connections. Power from the
(B2) battery stud is applied, through 30A fuse F10–A, to the spare accessory relay (167) common terminal.
With the key switch in the on or accessory position the relay is energized applying the power to the spare
accessory switch (517). When switch 517 is turned on, power is applied to circuit 14AQ.
Without Fuse

This option provides switched battery power on circuit 14AQ for owner/operator connections directly through
the spare accessory switch (517).

2.14. ELECTRIC LOCK - RIGHT AND LEFT

Power from the (B1) battery adapter is applied through 10A fuse F-10A to terminals 85 and 87 of power lock
relay (1139) and power lock relay – unlock (1140).

When driver switch (1042) or passenger switch (1043) are pushed to the unlock position, a ground from ground
adapter (456) will be applied through terminal 2B and terminal 3 of the actuated switch to terminal 86 of the
power lock relay – unlock (1140). This will energize the relay, applying 12 volts to terminal 30 of the relay,
circuits 81H, 81K and 81J to the left and right power locks. A ground from de-energized power lock relay (1139)
will be on terminal 30, circuit 81D, 81E and 81F to the left and right power locks. This will unlock the doors.

When driver switch (1042) or passenger switch (1043) are pushed to the lock position a ground from ground
adapter (456) will be applied through terminal 2B and terminal 1 of the actuated switch to terminal 86 of the
power lock relay (1139). This will energize the relay, applying 12 volts to terminal 30 of the relay, circuits 81D,
81E and 81F to the left and right power locks. A ground from de-energized power lock relay – unlock (1140)
will be on terminal 30, circuit 81H, 81J and 81K to the left and right power locks. This will lock the doors.

2.15. INTERVISION DISPLAY

The Intervision display receives battery power from the (B1) battery adapter through 5A fuse F10–A. Switched
ignition power is supplied from the (I2) ignition adapter through 5A fuse F10–B. Ground for the display unit is
supplied from the (G1) ground adapter. The unit connects to the truck data link on circuits 98G(+) and 98H(-).

2.16. EATON VORAD COLLISION AVOIDANCE EVT-300

The EATON VORAD Collision Avoidance EVT-300 CPU receives switched ignition power from the (I2) ignition
adapter through 5A fuse F10–B. Ground for the CPU is supplied from the (G1) ground adapter. The CPU is
connected to the driver display unit on circuits 73U, 73V, 73W and 73X. The CPU is connected to the front
antenna unit on circuits 73B, 73C, 73D and 73E. The CPU is connected to the right side sensor unit on circuits
73L, 73M and 73N. The CPU is connected to the right side display unit on circuits 73L, 73N and 73P. The CPU
is connected to the truck data link on circuits 98YL9(+) and 98GN9(-), also 98EV(+) and 98EV(-).

2.17. TEMPERATURE/COMPASS DISPLAY

The temperature and compass display receives battery power from the (B2) battery adapter through 5A fuse
F10–B. Switched ignition power is supplied from the (I1) ignition adapter through 5A fuse F10–A. Ground for
the display unit is supplied from the (G3) ground adapter. The unit connects to the temperature sensor on
circuits 41C and 41D. Also, the unit connects to the compass module on circuits 41F, 41H and 41J.

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28 2 CAB ACCESSORIES

2.18. ROAD RELAY IV

The road relay display module receives battery power from the (B2) battery adapter through 5A fuse F10–A.
Switched ignition power is supplied from the (I1) ignition adapter through 5A fuse F10–B. Ground for the
display unit is supplied from the (G1) ground adapter. The unit connects to the truck data link on circuits
98E(+) and 98D(-).

2.19. HEATED SEAT-DRIVER

The driver heated seat receives switched ignition power from the (I2) ignition adapter through 10A fuse F10–A.
Ground for the heated seat is from the (G3) ground adapter.

2.20. HEATED SEAT-PASSENGER

The passenger heated seat receives switched ignition power from the (I2) ignition adapter through 10A fuse
F10–A. Ground for the heated seat is from the (G3) ground adapter.

3. TROUBLESHOOTING
Refer to the CAB ACCESSORIES circuit diagrams in CTS-5298 or S08225 for the following discussion.

A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins, wires,
etc. Refer to section in GROUP 08 - ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not
covered in detail. It is assumed that the technician knows to check for a malfunctioning switch,
relay, or solenoid.

3.1. TESTING CIGAR LIGHTER (CAB)

Table 4 Testing Cigar Lighter (Cab)
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F2-A F2-A <1 ohm. Go to Locate cause of
and check for open next step. overload condition,
condition. then repair.
Replace fuse.

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 2 CAB ACCESSORIES 29

Table 4 Testing Cigar Lighter (Cab) (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off Re-install fuse F2-A and F2-A, 14T 12± 1.5 Go to Locate cause of no
measure voltage to gnd. to gnd. volts. next step. or low voltage in
at F2-A and circuit 14T. circuit 14T or 14W,
then repair.
3. Off At cigar lighter socket, Cigar 12± 1.5 Go to Locate cause of
measure voltage of Lighter, 84 volts. next step. no or low voltage
center electrical contact to gnd. in circuit 84, then
(circuit 84) to gnd. repair.
4. Off At cigar lighter socket, Cigar lighter, 12± 1.5 Go to Locate open or poor
measure voltage from 84 to 84-G. volts. next step. connection in circuit
center electrical contact 84-G or 11-GD to
to outer electrical ground, then repair.
contact (circuit 84 to
84-G).
5. Off Cigar lighter circuits
check good. If lighter
does not function,
replace defective lighter
or socket.

3.2. TESTING CLOCK (CAB)

Table 5 Testing Clock (Cab)
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove fuse F10-A and F10-A <1 ohm. Go to next Locate cause
check for open condition. step. of overload
condition, then
repair. Replace
fuse.
2. Off Re-install fuse F10-A and F10- A, 14N 12± 1.5 Go to next Locate cause of
measure voltage at F10-A to gnd. volts. step. no or low voltage
circuit 14N to ground. in circuit 14N,
then repair.
3. Off At analog clock connector (526), 88F to 12± 1.5 Go to next Locate cause of
(526), measure voltage at gnd. volts. step. no or low voltage
circuit 88F to ground. in circuit 88F, then
repair.

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30 2 CAB ACCESSORIES

Table 5 Testing Clock (Cab) (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
4. Off At connector (526) (526), 88F to 12± 1.5 Go to next Locate open or
measure voltage from 88-GF. volts. step. poor connection
circuit 88F to circuit 88-GF. in circuit 88-GF
or 11-GAV to
ground, then
repair.
5. Off Analog clock circuits check
good. If clock does not
function properly, replace
defective clock.

3.3. TESTING ELECTRIC WINDOW - RIGHT

Table 6 Testing Electric Window - Right
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove 20A fuse F4-B <1 ohm. Go to next Locate cause of
F4-B and check for step. overload condition,
open condition. then repair.
Replace fuse.
2. Off Re-install fuse F4-B. (1159), 83 12± 1.5 Go to next Locate cause of
Remove relay from to gnd. volts. step. no or low voltage,
connector (1159). then repair.
Measure voltage to
ground at circuit 83.
3. Off At connector (1159) (1159), 83 to 12± 1.5 Go to next Locate open or
measure voltage 12- GW. volts. step. poor connection
between circuits 83 in circuit 12-GW
and 12-GW. to ground, then
repair.
4. On At connector (1159) (1159), 12W 12± 1.5 Go to next Locate cause of no
measure voltage to 12- G. volts. step. or low voltage in
between circuits 12W circuit 12W, then
and 12-G. repair.
5. Off Measure resistance of 83D <5 ohms. Go to next Repair open or
circuit 83D between between step. poor connection in
connectors (1159) and (1159) and circuit 83D, then
(1158). (1158). repair.
6. Off/ On Install relay in (1158), 83D 12± 1.5 Go to next Replace the relay
connector (1159). to gnd. volts. step. in connector
Turn key on. At (1159).
connector (1158)
measure voltage to
ground at 83D.

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 2 CAB ACCESSORIES 31

Table 6 Testing Electric Window - Right (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
7. On At connector (1159) (1159), 83D 12± 1.5 Go to next Locate open or
measure voltage to 12-G. volts. step. poor connection in
between circuits 83D circuit 12-G ground
and 12-G. path, then repair.
8. Off Remove window Window <1 ohm. Go to next Replace the
switch. With switch switch, step. switch.
in neutral position between 1,
measure resistance 2 and 5.
between terminals 1, 2
and 5.
9. Off With switch in up Window <1 ohm. Go to next Replace the
position measure switch, 2 step. switch.
resistance between to 4.
terminals 2 and 4.
10. Off With switch in up Window <1 ohm. Go to next Replace the
position measure switch, 5 step. switch.
resistance between to 1.
terminals 5 and 1.
11. Off With switch in down Window <1 ohm. Go to next Replace the
position measure switch, 1 step. switch.
resistance between to 2.
terminals 1 and 2.
12. Off With switch in down Window <1 ohm. Go to next Replace the
position measure switch, 4 step. switch.
resistance between to 5.
terminals 4 and 5.
13. Off Disconnect motor at (1158), 83L >100K Go to next Locate short to
connector (1045). to gnd. ohms. step. ground in circuit
At connector (1158) 83L, then repair.
measure resistance to
gnd. at circuit 83L.
14. Off At connector (1158) (1158), 83M >100K Go to next Locate short to
measure resistance to to gnd. ohms. step. ground in circuit
gnd. at circuit 83M. 83M, then repair.
15. Off/ On Connect (1158) to (1045), 83L 12± 1.5 Go to next Locate open or
window switch. Turn to gnd. volts. step. poor connection
key on. With switch in circuit
in down position, 83L between
at connector (1045) connectors (1158)
measure voltage to and (1045), then
gnd. at circuit 83L. repair.

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32 2 CAB ACCESSORIES

Table 6 Testing Electric Window - Right (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
16. On With switch in down (1045), 83M 12± 1.5 Go to next Locate open or
position, at connector to 83L. volts. step. poor connection
(1045) measure in circuit
voltage between 83M between
circuits 83M and 83L. connectors (1158)
and (1045), then
repair.
17. Off Window control circuits
check good. If window
fails to operate, either
the mechanical parts or
the motor is defective.

3.4. TESTING ELECTRIC WINDOW - RIGHT AND LEFT

Table 7 Testing Electric Window - Right & Left
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. On Do any of the windows Any Go to next Go to Step 4.
operate from any window step.
control? operates.
2. On Does the left window Left Go to next Go to Step 9.
operate correctly? window step.
operates
correctly.
3. On Does the right window Right Windows Go to Step 20.
operate correctly from window operate
both the passenger operates correctly
and driver control? correctly
from both
controls.
4. Off Remove 20A fuse F4-B <1 ohm. Go to next Locate cause of
F4-B and check for step. overload condition,
open condition. then repair.
Replace fuse.
5. Off Re-install fuse F4-B. (1138), 83 12 ± 1.5 Go to next Locate cause of
Remove electric to gnd. volts. step. no or low voltage,
window relay from then repair.
connector (1138).
Measure voltage to
ground at circuit 83.

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 2 CAB ACCESSORIES 33

Table 7 Testing Electric Window - Right & Left (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
6. Off At connector (1138) (1138), 83 12 ± 1.5 Go to next Locate open or
measure voltage to 12-G. volts. step. poor connection
between circuits 83 in circuit 12-G
and 12-G. to ground, then
repair.
7. On At connector (1138) (1138), 12W 12 ± 1.5 Go to next Locate cause of no
measure voltage to 12-G. volts. step. or low voltage in
between circuits 12W circuit 12W, then
and 12-G. repair.
8. Off/ On Install relay in (1138), 83D 12 ± 1.5 Relay and Replace the relay
connector (1138). to gnd. volts. circuits in connector
Turn key on. Measure check (1138).
voltage to ground at good.
circuit 83D .
9. Off Remove driver side (1039), 83H Open Go to next Locate short to
left window switch to gnd. circuit. step. ground in circuit
from connector (1039). 83H or 83C, then
Measure resistance repair.
from (1039) circuit 83H
to ground.
10. Off/ On Turn key on. Measure (1039), 83H 12 ± 1.5 Go to next Locate cause of no
voltage to ground from to gnd. volts. step. or low voltage on
(1039), circuit 83H. circuit 83H, then
repair.
11. On Measure voltage (1039), 83H 12 ± 1.5 Go to next Locate open or
between (1039) to 83-GBW. volts. step. poor connection
circuit 83H and circuit in circuit 83-GBW,
83-GBW. 83–GA or 11–GAW
to ground, then
repair.
12. Off With driver side left Window <1 ohm. Go to next Replace the
switch in up position switch, 2B step. switch.
measure resistance to 4.
between switch
terminals 2B and 4.
13. Off With switch in up Window <1 ohm. Go to next Replace the
position measure switch, 5B step. switch.
resistance between to 1.
switch terminals 5B
and 1.
14. Off With switch in down Window <1 ohm. Go to next Replace the
position measure switch, 1 to step. switch.
resistance between 2B.
terminals 1 and 2B.

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34 2 CAB ACCESSORIES

Table 7 Testing Electric Window - Right & Left (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
15. Off With switch in down Window <1 ohm. Go to next Replace the
position measure switch, 4 to step. switch.
resistance between 5B.
terminals 4 and 5B.
16. Off Disconnect motor at (1039), 83F Open Go to next Locate short to
connector (1044). and 83N to circuit. step. ground in circuit
At connector (1039) gnd. 83F or 83N, then
measure resistance repair.
from 83F and 83N to
ground.
17. Off/ On Connect (1039) to (1044), 83N 12 ± 1.5 Go to next Locate open or
window switch. Turn to gnd. volts. step. poor connection
key on. With switch in circuit
in down position, 83N between
at connector (1044) connectors (1039)
measure voltage to and (1044), then
gnd. at circuit 83N. repair.
18. On With switch in down (1044), 83N 12 ± 1.5 Go to next Locate open or
position, at connector to 83F. volts. step. poor connection
(1044) measure in circuit
voltage between 83F between
circuits 83N and 83F. connectors (1039)
and (1044), then
repair.
19. Off Driver side left window
control circuits check
good. If window fails
to operate, either the
mechanical parts or
the motor may be
defective.
20. Off Remove driver’s side (1040), 83E Open Go to next Locate short to
right window switch to gnd. circuit. step. ground in circuit
from connector (1040). 83E, then repair.
Measure resistance
from (1040) circuit 83E
to ground.
21. Off/ On Turn key on. Measure (1040), 83E 12 ± 1.5 Go to next Locate cause of no
voltage to ground from to gnd. volts. step. or low voltage on
(1040), circuit 83E. circuit 83E, then
repair.

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 2 CAB ACCESSORIES 35

Table 7 Testing Electric Window - Right & Left (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
22. On Measure voltage (1040), 83E 12 ± 1.5 Go to next Locate open or
between (1040) circuit to 83-GB. volts. step. poor connection
83E and circuit 83-GB. in circuit 83-GB
to ground, then
repair.
23. Off With driver side right Window <1 ohm. Go to next Replace the
switch in neutral switch, step. switch.
position measure between 1,
resistance between 2B and 5B.
switch terminals 1, 2B
and 5B.
24. Off With switch in up Window <1 ohm. Go to next Replace the
position measure switch, 2B step. switch.
resistance between to 4.
switch terminals 2B
and 4.
25. Off With switch in up Window <1 ohm. Go to next Replace the
position measure switch, 5B step. switch.
resistance between to 1.
switch terminals 5B
and 1.
26. Off With switch in down Window <1 ohm. Go to next Replace the
position measure switch, 1 to step. switch.
resistance between 2B.
terminals 1 and 2B.
27. Off With switch in down Window <1 ohm. Go to next Replace the
position measure switch, 4 to step. switch.
resistance between 5B.
terminals 4 and 5B.
28. Off Measure resistance (1040), 83J Open Go to next Locate short to
from connector (1040) and 83K to circuit. step. ground in circuit
circuit 83J and 83K to gnd. 83J or 83K, then
ground. repair.
29. Off Install a jumper (1041), <1 ohm. Go to next Locate open in
between (1040) between 83J step. circuit 83J or 83K,
circuit 83J and 83K. and 83K. then repair.
Remove pasenger’s
side window switch
from connector (1041).
Measure resistance
between (1041) circuit
83J and 83K.

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36 2 CAB ACCESSORIES

Table 7 Testing Electric Window - Right & Left (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
30. Off Remove jumper from (1041), 83D Open Go to next Locate short to
connector (1040) and to gnd. circuit. step. ground in circuit
reconnect driver side 83D, then repair.
switch. Measure
resistance from (1041)
circuit 83D to ground.
31. Off/ On Turn key on. Measure (1041), 83D 12 ± 1.5 Go to next Locate open in
voltage from (1041) to gnd. volts step. circuit 83D, then
circuit 83D to ground. repair.
32. Off With passenger side Window <1 ohm. Go to next Replace the
switch in neutral switch, step. switch.
position measure between 1
resistance between and 2B.
switch terminals 1and
2B.
33. Off With switch in neutral Window <1 ohm. Go to next Replace the
position measure switch, step. switch.
resistance between between 6
switch terminals 6 and and 5B.
5B.
34. Off With switch in up Window <1 ohm. Go to next Replace the
position measure switch, 2B step. switch.
resistance between to 4.
switch terminals 2B
and 4.
35. Off With switch in up Window <1 ohm. Go to next Replace the
position measure switch, 5B step. switch.
resistance between to 1.
switch terminals 5B
and 1.
36. Off With switch in down Window <1 ohm. Go to next Replace the
position measure switch, 1 to step. switch.
resistance between 2B.
terminals 1 and 2B.
37. Off With switch in down Window <1 ohm. Go to next Replace the
position measure switch, 4 to step. switch.
resistance between 5B.
terminals 4 and 5B.
38. Off Disconnect motor at (1041), 83L Open Go to next Locate short to
connector (1045). to gnd. circuit. step. ground in circuit
At connector (1041) 83L, then repair.
measure resistance to
gnd. at circuit 83L.

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 2 CAB ACCESSORIES 37

Table 7 Testing Electric Window - Right & Left (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
39. Off At connector (1041) (1041), 83M Open Go to next Locate short to
measure resistance to gnd. circuit. step. ground in circuit
from 83M to gnd. 83M, then repair.
40. Off/ On Connect (1041) to (1044), 83M 12 ± 1.5 Go to next Locate open or
window switch. Turn to gnd. volts. step. poor connection
key on. With switch in circuit
in down position, 83M between
at connector (1045) connectors (1041)
measure voltage to and (1045), then
gnd. at circuit 83M. repair.
41. On With switch in down (1045), 83M 12 ± 1.5 Go to next Locate open or
position, at connector to 83L. volts. step. poor connection
(1045) measure in circuit
voltage between 83L between
circuits 83M and 83L. connectors (1041)
and (1045), then
repair.
42. Off Right window control
circuits check good.
If window fails to
operate, either the
mechanical parts or
the motor may be
defective.

3.5. TESTING DEFROSTER FAN(S)

Table 8 Testing Defroster Fan(s)
STEP KEY ACTION TEST POINTS SPEC. YES- IN NO-OUT OF
SPEC. SPEC.
1. Off/ Disconnect connector (313), 76F to 12± 1.5 Go to next Locate cause
On (313). Turn key on. At gnd. volts. step. of no or low
connector (313) measure voltage in
the voltage between circuit 76F
circuit 76F and gnd. or 86E, then
repair.
2. On At connector (313) (313), 76F to 12± 1.5 Go to next Locate open
measure the voltage gnd. volts. step. or poor
between 76F and 76-G. connection
in circuit
76-G, 11-GAC,
11GAB or
11-GB to
ground, then
repair.

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38 2 CAB ACCESSORIES

Table 8 Testing Defroster Fan(s) (cont.)

STEP KEY ACTION TEST POINTS SPEC. YES- IN NO-OUT OF
SPEC. SPEC.
3. Off/ Reconnect connector Orange wire to 12± 1.5 Go to next Locate open in
On (313). Remove the red black wire. volts. step. black wire or
and orange wire from the orange wire or
fan. Turn the key on and replace faulty
turn the defroster switch switch.
to HI. Measure the voltage
between the orange wire
and the black wire.
4. On Turn the defroster switch Red wire to 12± 1.5 Replace Locate open in
to LO. Measure the black wire. volts. faulty motor. black wire or
voltage between the red replace faulty
wire and the black wire. switch.

3.6. TESTING WINDSHIELD WIPER AND WASHER SYSTEM

NOTE – Intermittent wipe/wash is controlled by circuitry inside switch (1171). If high/low speed wipe and
wash work, but intermittent wipers and wash don’t, the switch needs to be replaced.

Perform this test if the wipers or wash do not work properly.

Table 9 Testing Windshield Wiper and Washer System

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. On Do any of the Some Go to next Go to Step 8.
washer/wiper functions washer/ step.
work? wiper
functions
work.
2. On Does the windshield Washer Go to next Go to Step 11.
washer work? works. step.
3. On Do the wipers work High speed Go to next Go to Step 14.
correctly with high speed wipers step.
selected? work.
4. On Do the wipers work Low speed Go to next Go to Step 23.
correctly with low speed wipers step.
selected? work.
5. On Do the wipers park Wipers Go to next Go to Step 31.
correctly when they are park step.
turned off? correctly.
6. On Do the wipers work Intermittent Wipers and Go to next step.
correctly with intermittent wipers washer
wipers selected? work. work
correctly.

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 2 CAB ACCESSORIES 39

Table 9 Testing Windshield Wiper and Washer System (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
7. On Intermittent wipe/wash
is controlled by circuitry
inside switch (1171).
If high/low speed wipe
and wash work, but
intermittent wipers don’t,
the switch needs to be
replaced.
8. Off Remove windshield (1171), Open Go to next Locate short to
washer w/wiper delay 12BC to circuit. step. ground on circuit
switch (1171). Measure gnd. 12BC.
resistance between
circuit 12BC and gnd.
9. On Turn ignition on. At (1171), 12 ± 1.5 Go to next Locate cause of
connector (1171) 12BC and volts. step. no or low voltage
measure voltage ground. on circuit 12BC,
between circuits 12BC check fuse F-10B,
and ground. then repair.
10. On At connector (1171) (1171), 12 ± 1.5 Power Locate open or
measure voltage 12BC and volts. circuits poor connection
between circuits 12BC 82-GB. to switch in circuit 82-GB,
and 82-GB. check then repair.
good.
Replace
switch.
11. Off Remove windshield (9), 87A to Open Go to next Locate short to
washer w/wiper delay gnd. circuit. step. ground on circuit
switch (1171). Remove 87A.
windshield washer pump
from connector (9).
Measure resistance
between circuit 87A and
gnd.
12. Off Install jumper from (9), 87A to <1 ohm. Remove Locate open in
(1171), terminal 5 to gnd. jumper. circuit 87A.
ground. Measure Go to next
resistance from (9) step.
circuit 87A to ground.

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40 2 CAB ACCESSORIES

Table 9 Testing Windshield Wiper and Washer System (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
13. Off Measure voltage (9), 87B and 12 ± 1.5 Circuits Locate cause of
between circuit 87B, gnd. volts. to washer no or low voltage
connector (9) and gnd. pump in circuit 87B,
motor then repair.
check
good.
Replace
switch
(1171).
14. Off Remove windshield 82J, <1 ohm. Go to next Locate open in
washer w/wiper delay between step. circuit 82J, then
switch (1171). Remove (1171) and repair.
wiper-high speed relay (142).
from connector (142).
Measure resistance
on circuit 82J between
(1171) and (142).
15. Off Reconnect the wiper Relay Go to next Replace relay.
switch to (1171). Bench checks step.
check wiper-high speed good.
relay (142).
16. Off Measure resistance from (142), 12BB Open Go to next Locate short to
(142) circuit 12BB to to ground. circuit. step. ground in circuit
ground. 12BB, then repair.
17. On Turn ignition on and (142), 12BB 12 ± 1.5 Go to next Locate cause of
measure the voltage to ground. volts. step. no or low voltage
between (142) circuit on circuit 12BB,
12BB and ground. then repair.
18. Off Measure voltage (142), 82K 12 ± 1.5 Go to next Locate cause of
between (142) circuit and gnd. volts. step. no or low voltage
82K and ground. on 82K.
19. Off Remove windshield (430), 82D Open Go to next Locate short to
wiper motor connector and gnd. circuit. step. ground on 82D.
(430). Measure
resistance between
(430) circuit 82D and
ground.
20. Off/ Connect wiper high (430), 82D 12 ± 1.5 Go to next Locate open on
On speed delay to (142). and gnd. volts step. 82D.
Turn ignition on and
select high speed
wiper. Measure voltage
between (430) circuit
82D and ground.

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 2 CAB ACCESSORIES 41

Table 9 Testing Windshield Wiper and Washer System (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
21. Off Measure resistance (430), <1 ohm. Go to next Locate open on
between (430) circuit 82-GC and step. 82-GC.
82-GC and ground. gnd.
22. Off Reconnect all switches Motor turns High speed Replace wiper
and relays. Turn ignition at high wipers motor.
on and select high speed speed. circuits
wipers. check
good.
23. Off Remove wiper-low Circuit 82A <1 ohm. Go to next Locate open or
speed relay (143) and (143)and step. poor connection
wiper high speed relay. (142). in circuit 82A,
Measure resistance of then repair.
circuit 82A between
(143) and (142).
24. On Turn ignition on. At (143), 12BA 12 ± 1.5 Go to next Locate open or
connector (143), to gnd. volts. step. poor connection
measure voltage to in circuit 12BA,
gnd. at circuit 12BA. then repair.
25. Off Bench check wiper-low Relay Go to next Replace relay.
speed relay (143). checks step.
good.
26. Off Remove windshield 82J, <1 ohm. Go to next Locate open in
washer w/wiper delay between step. circuit 82J, then
switch (1171). Measure (1171) and repair.
resistance on circuit (142).
82B between (1171) and
(143).
27. Off Reconnect the wiper Relay Go to next Replace relay.
switch to (1171). Bench checks step.
check wiper-low speed good.
delay relay (143).
28. Off Remove connector (430) (430), 82E Open Go to next Locate short to
from the wiper motor. to gnd. circuit. step. ground in circuit
Measure resistance 82E.
between 82E and gnd.
29. Off Install a jumper between (430), 82E <1 ohm. Go to next Locate open on
(143), circuit 82E and and ground. step. circuit 82E.
ground. Measure the
resistance between
(430), circuit 82E and
ground.

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42 2 CAB ACCESSORIES

Table 9 Testing Windshield Wiper and Washer System (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
30. Off Reconnect all switches Motor turns Low speed Replace wiper
and relays. Turn ignition at low wipers motor.
on and select low speed speed. circuits
wipers. check
good.
31. Off Remove wiper low (143), < 1 ohm. Install Replace wiper
speed delay relay (143). terminal 30 wiper low low speed delay
Measure resistance and 87A. speed relay (143).
between relay terminal delay relay
30 and 87A. (143). Go
to next
step.
32. Off Remove connector (430), circuit 12 ± 1.5 Go to next Locate cause of
(430) from wiper 82C and volts. step. no or low voltage
motor. Measure voltage gnd. in circuit 82C.
between circuit 82C and
gnd.
33. Off Measure resistance (430), circuit Open Go to next Locate short to
between (430) circuit 82E and circuit. step. ground in circuit
between circuit 82E and gnd. 82E or 82F.
gnd.
34. Off Measure resistance (430), circuit <1 ohm. Go to next Locate open in
between (430) circuit 82E and step. circuit 82E or 82F.
between circuit 82E and 82F.
82F.
35. On If wipers do not park
properly replace the
wiper motor assembly.

3.7. TESTING ELECTRIC HORN

Table 10 Testing Electric Horn
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove 15A fuse F5-C <1 ohm. Go to next Locate cause of
F5-C and check for step. overload condition,
open condition. then repair.
Replace fuse.
2. Off Re-install fuse F5-C. (463)/R7, 85/ 12± 1.5 Go to next Locate cause of no
Remove relay from 85D to gnd. volts. step. or low voltage from
connector (463-R7). fuse, then repair.
Measure voltage
to ground at circuit
85/85D.

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 2 CAB ACCESSORIES 43

Table 10 Testing Electric Horn (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
3. Off With horn button (463)/R7, 85 12± 1.5 Go to next Locate cause of
depressed, at to 85C. volts. step. open or poor
connector (463-R7) connection in
measure voltage horn control circuit
between circuits 85 between relay
and 85C. and horn button
ground, then
repair.
4. Off At connector (463-R7) Does horn Replace Go to next step.
use test lead to jumper sound? the horn
circuit 85 to 85B. relay.
5. Off With test leads, Does horn Go to next Replace the horn.
connect one side of sound? step.
horn to ground and the
other side to B1 battery
stud.
6. Off Check for open in horn
feed or ground circuit,
then repair.

3.8. HEATED AND LIGHTED MIRRORS

Testing Heated Mirrors

Table 11 Testing Heated Mirrors

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Check 15A fuse F5-A F5-A <1 ohm. Go to next Locate cause of
for open condition. step. overload condition,
then repair.
Replace fuse.
2. Off Does the right side Right Go to next Go to Step 6.
mirror work? heated step.
mirror
works.
3. Off Does the left side Left heated Heated Go to next step.
mirror work? mirror mirrors
works. work.
4. Off/ Disconnect connector (1127), 78B 12± 1.5 Go to next Locate open or
On (1127). Turn key on to gnd. volts. step. poor connection in
and measure voltage circuit 78B, then
to gnd. at circuit 78B. repair.

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44 2 CAB ACCESSORIES

Table 11 Testing Heated Mirrors (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
5. On At connector (1127) Both (1127), 12± 1.5 Replace Locate open or
measure voltage 78B and 11- volts. heater poor connection
between circuits 78B GBM. element. in circuit 11-GBM,
and 11-GBM. then repair.
6. On At connector (1128) Both (1128), 12± 1.5 Go to next Locate open or
measure voltage to 78A to gnd. volts. step. poor connection in
gnd. at circuit 78A. circuit 78A, then
repair.
7. On At connector (1128) Both (1128), 12±1 .5 Replace Locate open or
measure voltage 78B and 11- volts. heater poor connection
between circuits 78A GY. element. in circuit 11-GY
and 11-GY. path to gnd., then
repair.

Testing Mirror Lights

Table 12 Testing Mirror Lights

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off With headlight switch F8-C <1 ohm. Go to next Locate cause of
off, check 15A step. overload condition,
fuse F8-C for open then repair.
condition. Replace fuse.
2. Off Check mirror light Go to next Replace bulb.
bulb(s) for open step.
filament. Bulb OK?
3. On With headlight and (1127) and 12± 1.5 Go to next Locate cause of no
trailer light switch on, (1128), 58L volts. step. or low voltage in
disconnect connectors and 58J to circuit 58J, 58L or
(1127) and (1128). gnd. other circuits from
Measure voltage to fuse F8-C, then
gnd. at circuit 58J and repair.
58L.
4. On With headlight and (1127) and 12± 1.5 Circuits Locate open in
trailer light switch on, (1128), 58L to volts. to mirror circuit 11-GBM or
disconnect connectors 11-GBM and lights check 11-GY, then repair.
(1127) and (1128). 58J to 11-GY. good.
Measure voltage at
circuit 58J to circuit
11-GBM and 58L to
11-GY.

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 2 CAB ACCESSORIES 45

3.9. MOTORIZED MIRRORS

Testing Right Motorized Mirror

Table 13 Testing Right Motorized Mirror

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Check 15A fuse F5-A F5-A <1 ohm. Go to next Locate cause of
for open condition. step. overload condition,
then repair.
Replace fuse.
2. Off/ On Disconnect connector (437), 78C 12± 1.5 Go to next Locate cause of
(437) from motorized to gnd. volts. step. no or low voltage
mirror switch. Turn key in circuit 78C from
on. At connector (437) fuse, then repair.
measure voltage to
ground at circuit 78C.
3. On At connector (437) (437), 78C 12± 1.5 Go to next Locate open or
measure voltage to 78-GA. volts. step. poor connection in
between circuits 78C circuit 78-GA path
and 78-GA. to ground, then
repair.
4. Off With switch (437) in Mirror <1 ohm. Go to next Replace the
up position, measure switch, 1 step. switch.
resistance between to 5.
terminals 1 and 5.
5. Off With switch (437) in Mirror <1 ohm. Go to next Replace the
up position, measure switch, 2 step. switch.
resistance between to 4.
terminals 2 and 4.
6. Off With switch (437) Mirror <1 ohm. Go to next Replace the
in down position, switch, 1 to 2 step. switch.
measure resistance
between terminals 1
and 2.
7. Off With switch (437) Mirror <1 ohm. Go to next Replace the
in down position, switch, 4 step. switch.
measure resistance to 5.
between terminals 4
and 5.
8. Off With switch (437) Mirror >100K Go to next Replace the
in neutral position, switch, 4 ohms. step. switch.
measure resistance to 5.
between terminals 4 to
5.

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46 2 CAB ACCESSORIES

Table 13 Testing Right Motorized Mirror (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
9. Off With switch (437) Mirror >100K Go to next Replace the
in neutral position, switch, 5 ohms. step. switch.
measure resistance to 6.
between terminals 5
and 6.
10. Off With switch (437) Mirror >100K Go to next Replace the
in neutral position, switch, 1 to 2 ohms. step. switch.
measure resistance
between terminals 1
and 2.
11. Off With switch (437) Mirror >100K Go to next Replace the
in neutral position, switch, 2 ohms. step. switch.
measure resistance to 3.
between terminals 2
and 3.
12. Off Use diode test feature Go to next
of fluke meter to test step.
the LED in the switch if
it is not operating.
13. Off/ On Disconnect connector (1128), 78F 12 ± 1.5 Go to next Locate open or
(1128). Turn key on. to gnd. volts. step. poor connection
With switch in position in circuit 78F, then
that closes contacts repair.
between terminal 4
and 5, at (70) measure
voltage to ground at
circuit 78F.
14. On With switches still set, (1128), 78F 12 ± 1.5 Go to next Locate open or
at (1128) measure to 78E. volts. step. poor connection in
voltage between circuit 78E, then
circuits 78F and 78E. repair.
15. Off The control circuits
to mirror motor check
good. If the mirror
still does not operate
properly, replace the
motor assembly.

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 2 CAB ACCESSORIES 47

Testing Dual Axis Motorized Mirrors

Table 14 Testing Dual Axis Motorized Mirrors

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Check 15A fuse F5-A for F5-A <1 ohm. Go to next Locate cause
open condition. step. of overload
condition, then
repair. Replace
fuse.
2. Off/ Disconnect connector (1137), 78C 12 ± 1.5 Go to next Locate cause
On (1137) from motorized to gnd. volts. step. of no or low
mirror switch. Turn key voltage in
on. At connector (1137) circuit 78C
measure voltage to ground from fuse, then
at circuit 78C. repair.
3. On At connector (1137) (1137), 78C 12 ± 1.5 Go to next Locate open
measure voltage between to 78-GA. volts. step. or poor
circuits 78C and 78-GA. connection in
circuit 78-GA
path to gnd,
then repair.
4. Off Turn the mirror switch Mirror switch, <1 ohm. Go to next Replace the
(1137) knob to left (A to D) and step. switch.
position. Push the knob (H to C).
to up position, measure
resistance from terminals
(A to D) and H to C).
5. Off Turn the mirror switch Mirror switch, <1 ohm. Go to next Replace the
(1137) knob to left (A to C) and step. switch.
position. Push the knob (H and D).
to down position, measure
resistance from terminals
(A to C) and (H to D).
6. Off Turn the mirror switch Mirror switch <1 ohm. Go to next Replace the
(1137) knob to left (A to B) and step. switch.
position. Push the knob H and C).
to right position, measure
resistance from terminals
(A to B) and (H and C).
7. Off Turn the mirror switch Mirror switch, <1 ohm. Go to next Replace the
(1137) knob to left (A to C) and step. switch.
position. Push the knob (H and B).
to left position, measure
resistance from terminals
(A to C) and (H to B).

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48 2 CAB ACCESSORIES

Table 14 Testing Dual Axis Motorized Mirrors (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
8. Off Turn the mirror switch Mirror switch, <1 ohm. Go to next Replace the
(1137) knob to right (A to E) and step. switch.
position. Push the knob (H to F).
to up position, measure
resistance from terminals
(A to E) and (H to F).
9. Off Turn the mirror switch Mirror switch, <1 ohm. Go to next Replace the
(1137) knob to right (A to F) and step. switch.
position. Push the knob (H to E).
to down position, measure
resistance from terminals
(A to F) and (H to E).
10. Off Turn the mirror switch Mirror switch, <1 ohm. Go to next Replace the
(1137) knob to right (A to F) and step. switch.
position. Push the knob (H to G).
to left position, measure
resistance from terminals
(A to F) and (H to G).
11. Off Turn the mirror switch Mirror switch, <1 ohm. Go to next Replace the
(1137) knob to right (A to G) and step. switch.
position. Push the knob (H to F).
to right position, measure
resistance from terminals
(A to G) and (H to F).
12. Off With switch (1137) in All mirror >100K Go to next Replace the
neutral position, measure switch ohms. step. switch.
resistance between all of terminals.
the terminals.
13. Off/ Reconnect connector Check Left mirror Go to next Go to Step 15.
On (1137). Turn ignition key left mirror operates step.
to ACC position. Verify operation. correctly.
operation of the left mirror.
14. On Verify operation of the right Right Mirror Go to Step 17.
mirror. mirror circuits
operates check
correctly. good.

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 2 CAB ACCESSORIES 49

Table 14 Testing Dual Axis Motorized Mirrors (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
15. On Disconnect connector (70), 58J to 12 ± 1.5 Go to next Locate open
(1127) going to the left 78P. volts. step. or poor
mirror. Turn the switch connection in
knob to the "L" position. circuits 58J,
Have an assistant hold the 78R, or 78P,
switch in the up position. then repair.
Measure voltage from
middle pin of the three
small connectors, to the
next pin counter clockwise
from the middle pin.
16. On Have an assistant hold the (1127), 78P 12 ± 1.5 Left mirror Locate open
switch in the left position. to 78N. volts. circuits or poor
Measure voltage between check connection
two outer pins of the good. in circuit 78P
three small connectors of or 78N, then
connector (1127). repair.
17. On Disconnect connector (1128), 58L to 12 ± 1.5 Go to next Locate open
(1128) going to the right 78F. volts. step or poor
mirror. Turn the switch connection in
knob to the "R" position. circuits 58L
Have an assistant hold the or 78F, then
switch in the up position. repair.
Measure voltage from
middle pin of the three
small connectors, to the
next pin counter clockwise
from the middle pin.
18. On Have an assistant hold the (1128), 58L to 12 ± 1.5 Right mirror Locate open
switch in the left position. 78E. volts. circuits or poor
Measure voltage between check connection
two outer pins of the good. in circuit 58L
three small connectors of or 78F, then
connector (1128). repair.

3.10. TESTING CB POWER SOURCE

Table 15 Testing CB Power Source
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove 20A fuse F5-D F5-D <1 ohm. Go to next Locate cause of
and check for open step. overload condition,
condition. then repair.
Replace fuse.

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50 2 CAB ACCESSORIES

Table 15 Testing CB Power Source (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
2. Off Re-install fuse F5-D and F5-D, 14AA 12 ± 1.5 Go to next Locate cause of
measure voltage to gnd. at to gnd. volts. step. no or low voltage
F5-D and circuit 14AA. in circuit 14AA or
14W, then repair.
3. Off At positive terminal of Positive 12 ± 1.5 Go to next Locate cause of
terminal block or cigar term. 86K volts. step. no or low voltage
lighter socket, measure to gnd. in circuit 86K, then
voltage (circuit 86K) to gnd. repair.
4. Off At terminal block or cigar Power 12 ± 1.5 Go to next Locate open or
lighter socket, measure source 86K volts. step. poor connection
voltage from circuit 86K to to 86-GK. in circuit 86-GK or
86-GK. 11-GI to gnd., then
repair.
5. Off CB power source circuits
check good.

3.11. TESTING RADIO-CB ACCOMMODATION PACKAGE

Table 16 Testing Radio-CB Accommodation Package
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Check fuse F5-B for open F5-B <1 ohm. Go to next Locate cause of
condition. step. overload condition,
then repair. Replace
fuse.
2. On With ignition on, measure F5-B, 12 ± 1.5 Go to next Locate cause of no
voltage to gnd. at F5-B and 12M to volts. step. or low voltage in
circuit 12M. gnd. circuit 12M, then
repair.
3. Off/ Disconnect connector (428), 12 ± 1.5 Go to next Locate cause of
On (428). Turn ignition on 86E to volts. step. no or low voltage
and measure voltage from gnd. in circuit 86E, then
circuit 86E coming from repair.
F5-B to gnd.
4. Off/ Disconnect connector (525), 12 ± 1.5 Go to next Locate cause of no
On (525) and reconnect 86AE to volts. step. or low voltage in
connector (428). Turn gnd. circuit 86AE, then
ignition on and at (525) repair.
measure voltage from
circuit 86AE to gnd.

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 2 CAB ACCESSORIES 51

Table 16 Testing Radio-CB Accommodation Package (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
5. Off At connector (525), (525), 12 ± 1.5 Go to next Locate open or poor
measure voltage from 86AE to volts. step. connection in circuit
circuit 86AE to 86-GE. 86-GE. 86-GE, 11-GAC,
11-GAB, or 11-GB to
gnd., then repair.
6. Off Disconnect CB speaker Across 3.5 to 8 Go to next Replace defective
connector, and measure CB ohms. step. speaker assembly.
resistance across speaker
connector terminals. connector.
7. Off CB power and speaker
circuits check good.

3.12. TESTING RADIO-CAB SPEAKERS

Table 17 Testing Radio-Cab Speakers
STEP KEY ACTION TEST POINTS SPEC. YES- IN NO-OUT OF
SPEC. SPEC.
1. Off Check fuse F5-B for open F5-B <1 ohm. Go to next Locate cause
condition. step. of overload
condition, then
repair. Replace
fuse.
2. On With ignition on, measure F5-B, 12M to 12 ± 1.5 Go to next Locate cause
voltage to gnd. at F5-B gnd. volts. step. of no or low
and circuit 12M. voltage in circuit
12M, then
repair.
3. Off/ Disconnect connector (426), 86 to gnd. 12 ± 1.5 Go to next Locate cause
On (426). Turn ignition on volts. step. of no or low
and measure voltage voltage in circuit
from circuit 86 to gnd. 86, then repair.
4. On Disconnect connector (426), 86 to 12 ± 1.5 Go to next Locate open or
(427) and measure (427), 86-GA. volts. step. poor connection
voltage from (426) circuit in circuit 86-GA
86 to (427) 86-GA. or 11-GD to
ground, then
repair.
5. Off Remove fuse F5-C and F5-C <1 ohm. Go to next Locate cause
check for open condition. step. of overload
condition, then
repair. Replace
fuse.

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52 2 CAB ACCESSORIES

Table 17 Testing Radio-Cab Speakers (cont.)

STEP KEY ACTION TEST POINTS SPEC. YES- IN NO-OUT OF
SPEC. SPEC.
6. Off Re-install fuse F5-C F5-C, 14AM 12 ± 1.5 Go to next Locate cause
and measure voltage to to gnd. volts. step. of no or low
ground at F5-C and circuit voltage in circuit
14AM. 14AM, then
repair.
7. Off At connector (426), (426), 88B to 12 ± 1.5 Go to next Locate cause
measure voltage from gnd. volts. step. of no or low
circuit 88B to gnd. voltage in circuit
88B, then repair.
8. Off Was the right front Go to Step Go to next step.
speaker functional prior 11.
to being disconnected for
this test?
9. Off Disconnect connector Across right 3.5 to 8 Go to next Replace
(529), and measure front speaker. ohms. step. defective
resistance across right speaker
front speaker. assembly.
10. Off Reconnect connector (426), 86C to 3.5 to 9 Go to next Locate open or
(529). At (426) measure 86D. ohms. step. poor connection
resistance across circuits in circuit 86C or
86C and 86D. 86D, then repair.
11. Off Was the left front speaker Go to Step Go to next step.
functional prior to being 14.
disconnected for this
test?
12. Off Disconnect connector Across left front 3.5 to 8 Go to next Replace
(530), and measure speaker. ohms. step. defective
resistance across left speaker
front speaker. assembly.
13. Off Reconnect connector (426), 86A to 3.5 to 9 Go to next Locate open or
(530). At connector 86B. ohms. step. poor connection
(426) measure resistance in circuit 86A or
across circuits 86A and 86B, then repair.
86B.
14. Off Was the right rear Go to Step Go to next step.
speaker functional prior 18.
to being disconnected for
this test?
15. Off Disconnect connector Across right 3.5 to 8 Go to next Replace
(528), and measure rear speaker. ohms. step. defective
resistance across right speaker
rear speaker. assembly.

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 2 CAB ACCESSORIES 53

Table 17 Testing Radio-Cab Speakers (cont.)

STEP KEY ACTION TEST POINTS SPEC. YES- IN NO-OUT OF
SPEC. SPEC.
16. Off Reconnect connector (489), 86U to 3.5 to 9 Go to next Locate open or
(528) and disconnect 86T. ohms. step. poor connection
connector (489). in circuit 86U or
Measure resistance 86T, then repair.
across circuits 86U and
86T.
17. Off Reconnect connector (427), 86W to 3.5 to 9 Go to next Locate open or
(489) and disconnect 86V. ohms. step. poor connection
sleeper speaker in circuit
connector (427). At 86W/86U or
(427) measure resistance 86V/86T, then
across circuits 86W and repair.
86V.
18. Off Was the left rear speaker Go to Step Go to next step.
functional prior to being 22.
disconnected for this
test?
19. Off Disconnect connector Across left rear 3.5 to 8 Go to next Replace
(531), and measure speaker. ohms. step. defective
resistance across left rear speaker
speaker. assembly.
20. Off Reconnect connector (489), 86R to 3.5 to 9 Go to next Locate open or
(531) and disconnect 86S. ohms. step. poor connection
connector (489). in circuit 86R or
Measure resistance 86S, then repair.
across circuits 86R and
86S.
21. Off Reconnect connector (427), 86N to 3.5 to 9 Go to next Locate open or
(489) and disconnect 86P. ohms. step. poor connection
sleeper speaker in circuit
connector (427). At 86N/86R or
(427) measure resistance 86P/86S, then
across circuits 86N and repair.
86P.
22. Off Power and speaker
circuits check good.
Reconnect all circuits.

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3.13. TESTING OWNER/OPERATOR SPARE SWITCH (FUSED)

Table 18 Testing Owner/Operator Spare Switch (Fused)
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F10-A and F10-A <1 ohm. Go to next Locate cause of
check for open condition. step. overload condition,
then repair.
Replace fuse.
2. Off Re-install fuse F10-A, F10-A, 14AR 12 ± 1.5 Go to next Locate cause of no
and measure voltage to gnd. volts. step. or low voltage in
from circuit 14AR to circuit 14AR, then
ground. repair.
3. Off Remove relay from (167), 14AS 12 ± 1.5 Go to next Locate cause of no
connector socket (167). to gnd. volts. step. or low voltage in
Measure voltage to gnd. circuit 14AS, then
at circuit 14AS. repair.
4. Off At connector socket (167), 14AS 12 ± 1.5 Go to next Locate open or poor
(167) measure voltage to 12-GS. volts. step. connection in circuit
between circuits 14AS 12-GS or 11-GAL
and 12-GS. to panel lights gnd.
adapter, then repair.
5. Off At connector socket (167), 12S to 12 ± 1.5 Go to next Locate cause of
(167) measure voltage 12-GS. volts. step. no or low voltage
between circuits 12S and in circuit 12S, then
12-GS. repair.
6. Off Bench test accessories Acc. relay, 30 <1 ohm. Go to next Replace defective
relay (167) by measuring to 87A. step. relay.
resistance from terminal
30 to 87A.
7. Off Bench test accessories Energized <1 ohm. Go to next Replace defective
relay (167) by connecting acc. relay, step. relay.
+12 volts to terminal 86 30 to 87.
of accessory relay, and
ground to terminal 85.
Measure resistance from
terminal 30 to 87.
8. Off/ Re-install accessory (517), 14AF 12 ± 1.5 Go to next Locate cause of no
On relay, and disconnect to gnd. volts. step. or low voltage in
connector (517) from circuit 14AF, then
switch. Switch ignition repair.
on, and measure voltage
from circuit 14AF to
ground.
9. On At (517) measure voltage (517), 14AF 12 ± 1.5 Go to next Locate open or poor
from circuit 14AF to to 62-GU. volts. step. connection in circuit
62-GU. 62-GU, then repair.

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Table 18 Testing Owner/Operator Spare Switch (Fused) (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF SPEC.
POINTS SPEC.
10. On Switch headlamps on, (517), 62U 12 ± 1.5 Go to next Locate cause of no
and at (517) measure to gnd. volts. step. or low voltage in
voltage from circuit 62U circuit 62U, then
to ground. repair.
11. Off With accessory switch in Across switch <1 ohm. Go to next Replace defective
the on position, measure terminals. step. switch.
resistance across switch
terminals that connect
with cavity 5 and 6 of
connector (517).
12. Off With accessory switch in Across switch >100K Go to next Replace defective
the off position, measure terminals. ohms. step. switch.
resistance across switch
terminals that connect
with cavity 5 and 6 of
connector (517).
13. Off/ Reconnect connector (517), 14AQ 12 ± 1.5 Go to next Locate cause of no
On (517), switch ignition and to gnd. volts. step. or low voltage in
accessories switch to on, circuit 14AQ, then
and measure voltage at repair.
output of circuit 14AQ to
ground.
14. Off Spare switch circuits
check good.

3.14. TESTING OWNER/OPERATOR SPARE SWITCH (NON-FUSED)

Table 19 Testing Owner/Operator Spare Switch (Non-Fused)
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Disconnect connector (517), 62H 12 ± 1.5 Go to Locate cause of no
(517). Switch headlamps to gnd. volts. next step. or low voltage in
on, and measure voltage circuit 62H, then
from circuit 62H to ground repair.
at (517).
2. Off With headlights on, (517), 62H to 12 ± 1.5 Go to Locate open or
measure voltage from 62- GH. volts. next step. poor connection in
circuit 62H to 62-GH at circuit 62-GH, then
(517). repair.

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Table 19 Testing Owner/Operator Spare Switch (Non-Fused) (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
3. Off With accessory switch in Across <1 ohm. Go to Replace defective
the on position, measure switch next step. switch.
resistance across switch terminals.
terminals that connect with
cavity 5 and 6 of connector
(517).
4. Off With accessory switch in Across >100K Go to Replace defective
the off position, measure switch ohms. next step. switch.
resistance across switch terminals.
terminals that connect with
cavity 5 and 6 of connector
(517).
5. Off Spare switch circuits
check good. Reconnect
connector (517).

3.15. TESTING ELECTRIC LOCK – RIGHT AND LEFT

Table 20 Testing Electric Lock – Right and Left
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove power lock relay- (1140), 81A 12 ± 1.5 Go to Locate cause of no
unlock (1140). Measure to gnd. volts. next step. or low voltage in
voltage from circuit 81A to circuit 81A, 81 or
ground. fuse F10-A, then
repair.
2. Off Bench check power lock Relay (1140). Relay Go to Replace defective
relay-unlock (1140). bench next step. relay.
checks
good.
3. Off At (1140), measure (1140), <1 ohm. Go to Locate open in
resistance between circuit 81-GB to next step. circuit 81-GB, then
81-GB and ground. gnd. repair.
4. Off Remove power lock relay (1139), 81C 12 ± 1.5 Go to Locate cause of no
(1139). Measure voltage to gnd. volts. next step. or low voltage in
from circuit 81C to ground. circuit 81C or 81B,
then repair.
5. Off Bench check power lock Relay (1139). Relay Go to Replace defective
relay (1139). bench next step. relay.
checks
good.
6. Off At (1139), measure (1139), <1 Ohm. Go to Locate open in
resistance between circuit 81-GA to next step. circuit 81-GA, then
81-GA and ground. gnd. repair.

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Table 20 Testing Electric Lock – Right and Left (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
7. Off At (1140), measure (1140), 81H Open Go to Locate short to
reistance from circuit to ground. circuit. next step. ground in circuit
81H to ground. 81H, 81J, or 81K,
left power lock or
right power lock,
then repair.
8. Off At (1139), measure (1140), 81D Open Go to Locate short to
reistance from circuit to ground. circuit. next step. ground in circuits
81D to ground. 81D, 81F, or 81E,
left power lock or
right power lock,
then repair.
9. Off Remove connector (1046) Go to
from the left power lock next step.
and (1047) from the right
power lock.
10. Off Connect a jumper between (1139), 81D <1 ohm. Go to Locate open in
connector (1046), circuits and (1140), next step. circuits 81D, 81F,
81F and 81K. Measure the 81H. 81H or 81K.
resistance between (1139)
circuit 81D and (1140)
circuit 81H.
11. Off Connect a jumper between (1139), 81D <1 ohm. Remove Locate open in
connector (1047), circuits and (1140), jumper. circuits 81D, 81E,
81E and 81J. Measure the 81H. Go to 81H or 81J.
resistance between (1139) next step.
circuit 81D and (1140)
circuit 81H.
12. Off Test each power lock by Each power Lock Reconnect Replace defective
applying 12 volts to one lock. should (1139) power lock.
terminal and gnd. to the actuate. and
other, then reverse polarity. (1140) to
power
locks.Go
to next
step.
13. Off Remove driver switch Driver switch <1 Ohm Go to Replace switch
(1042). With switch in the (1042), next step. (1042).
lock position, measure terminal 2B
resistance between and 1.
terminal 2B and 1.
14. Off With switch in the unlock Driver switch <1 Ohm Go to Replace switch
position, measure (1042), next step. (1042).
resistance between terminal 2B
terminal 2B and 3. and 3.

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Table 20 Testing Electric Lock – Right and Left (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
15. Off At (1042), measure (1042), <1 ohm. Go to Locate open in
resistance between circuit 91-GG and next step. circuit 91-GG,
91-GG and ground. ground. 91-GC or 91-G.
16. Off At (1042), measure (1042), 81M Open Go to Locate short to
resistance between circuit and ground. circuit. next step. gnd. in circuit 81M
81M and ground. or 81L.
17. Off At (1042), measure (1042), 81N Open Go to Locate short to
resistance between circuit and ground. circuit. next step. gnd. in circuit 81N
81N and ground. or 81P.
18. Off At (1042), install a jumper (1139), 81M <1 ohm. Remove Locate open in
between circuit 81M and and (1140), jumper. circuit 81M or 81N,
81N. Measure resistance 81N. Go to then repair.
between (1139) circuit 81M next step.
and (1140) circuit 81N.
19. Off Remove passenger switch Passenger <1 ohm. Go to Replace switch
(1043). With switch in the switch next step. (1043).
lock position, measure (1043),
resistance between terminal 2B
terminal 2B and 1. and 1.
20. Off With switch in the unlock Passenger <1 ohm. Go to Replace switch
position, measure switch next step. (1043).
resistance between (1043),
terminal 2B and 3. terminal 2B
and 3.
21. Off At (1043), measure (1043), <1 ohm. Go to Locate open in
resistance between circuit 81-GG and next step. circuit 81-GG,
81-GJ and ground. ground. 81-GC or 81-G.
22. Off At (1043), measure (1043), 81L Open Go to Locate short to
resistance between circuit and ground. circuit. next step. gnd. in circuit 81L
81L and ground. or 81M.
23. Off At (1043), measure (1043), 81P Open Go to Locate short to
resistance between circuit and ground. circuit. next step. gnd. in circuit 81P
81P and ground. or 81N.
24. Off At (1043), install a jumper (1139), 81M <1 ohm. Remove Locate open in
between circuit 81L and and (1140), jumper. circuit 81L or 81P,
81P. Measure resistance 81N. Go to then repair.
between (1139) circuit 81M next step.
and (1140) circuit 81N.

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Table 20 Testing Electric Lock – Right and Left (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
25. Off Remove (1043), install (1139), 81L <1 ohm. Remove Locate open in
a jumper between circuit and (1140), Jumper. circuit 81L or 81P,
81L and 81P. Measure 81P. Go to then repair.
resistance between (1139) next step.
circuit 81L and (1140)
circuit 81P.
26. Off Reconnect all connectors
and relays. Power lock
circuits check good. If
power locks are not
operating check for a
mechanical failure in the
lock mechanism.

3.16. TESTING INTERVISION CIRCUITS

Table 21 Testing InterVision Circuits
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. On Does the InterVision Go to Go to next step.
module have a visible Step 6.
display?
2. Off/ On Disconnect the 13M to gnd. 12 ± 1.5 Go to Locate cause of no
InterVision display volts. next step. or low voltage in
connector (1156). Turn circuit 13M, then
ignition on, and measure repair.
voltage from circuit 13M
to ground.
3. On Measure voltage from 13M to 12 ± 1.5 Go to Locate open in
circuit 13M to 11-GK. 11-GK. volts. next step. circuit 11-GK, then
repair.
4. Off Measure voltage from 14B to 12 ± 1.5 Go to Locate cause of
circuit 14B to ground. ground. volts. next step. no or low voltage
in circuit 14B, then
repair.
5. Off With headlights on and 62W to 12 ± 1.5 Power Locate cause of no
panel lights all the way ground. volts. circuits or low voltage in
up, measure voltage from check circuit 62W, then
circuit 62W to ground. good. repair.
Replace
InterVision
module.

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Table 21 Testing InterVision Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
6. Off Does the InterVision Display Go to If InterVision is not
display show a problem shows next step. working correctly,
receiving data from the problem replace the module.
data link? with data
link.
7. Off Disconnect data link pos. (1156), Open Go to Locate short to
connector (514) and data 98H(-) and circuit. next step. ground in circuit
link neg. connector (515). 98G (+) to 98H(-) or 98G (+),
At (1156), measure ground. then repair.
resistance from circuit
98H(-) and 98G (+) to
ground.
8. Off Connect a jumper (1156), <1 ohm. Data link Locate open in
between data link pos. 98H(-) and circuits circuit 98H(-) or
connector (514), cavity 98G (+). check 98G (+), then
F and data link neg. good. Go repair.
connector (515), cavity to next
F. At (1156), measure step to
resistance between check
circuit 98H(-) and 98G RS- 232
(+). circuits.
9. Off At (1156), measure (1156), 91A, Open Go to Locate short to
resistance from circuits 91 to ground. circuit. next step. ground in circuits
91A and 91 to ground. 91A and 91, then
repair.
10. Off Connect a jumper (1156), 91A <1 ohm. Go to Locate open in
between RS-232 and 91. next step. circuit 91A or 91,
connector (1170), circuit then repair.
91A and circuit 91.
At (1156), measure
resistance between
circuit 91A and 91.
11. Off Connect a jumper (1156), 91A <1 ohm. All Inter- Locate open in
between RS-232 and 91-G. Vision circuit 91A or 91-G,
connector (1170), circuit circuits then repair.
91A and circuit 91-G. check
At (1156), measure good.
resistance between Replace
circuit 91A and 91-G. Inter-
Vision
module.

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 2 CAB ACCESSORIES 61

3.17. TESTING EATON VORAD COLLISION AVOIDANCE EVT-300 CIRCUITS

Table 22 Testing EATON VORAD Collision Avoidance EVT-300 Circuits
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. On Does the EATON VORAD Go to Go to next step.
Collision Avoidance Step 6.
EVT-300 module have
a visible display?
2. Off/ Disconnect the EATON 73A to gnd. 12 ± 1.5 Go to Locate cause of
On VORAD Collision volts. next step. no or low voltage
Avoidance EVT-300 CPU in circuit 73A,
connector (1227). Turn then repair.
ignition on, and measure
voltage from circuit 73A to
ground.
3. On Measure voltage from 73A to 73GA. 12 ± 1.5 Go to Locate open in
circuit 73A to 73GA. volts. next step. circuit 73GA, then
repair.
4. Off Press brake on. Measure 73H to 12 ± 1.5 Go to Locate cause of
voltage from circuit 73H to ground. volts. next step. no or low voltage
ground. in circuit 73H,
then repair.
5. Off With headlights on and 73J to 12 ± 1.5 Power Locate cause of
panel lights all the way ground. volts. circuits no or low voltage
up, measure voltage from check in circuit 73J, then
circuit 73J to ground. good. repair.
Replace
EVT-300
CPU.
6. Off Does the Driver display Display Go to If driver display
show a problem receiving shows next step. is not working
data from the data link? problem correctly, replace
with data the display.
link.
7. Off Disconnect data link (1227), Open Go to Locate short
pos. connector (514) and 98EV(-) and circuit. next step. to ground in
data link neg. connector 98EV(+) to circuit 98EV(-)
(515). At (1227), measure ground. or 98EV(+), then
resistance from circuit repair.
98EV(-) and 98EV(+) to
ground.

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62 2 CAB ACCESSORIES

Table 22 Testing EATON VORAD Collision Avoidance EVT-300 Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
8. Off Connect a jumper between (1227), <1 ohm. Data link Locate open in
data link pos. connector 98EV(-) and circuits circuit 98EV(-)
(514), cavity F and data 98EV(+). check or 98EV(+), then
link neg. connector good. repair.
(515), cavity F. At (1227), Replace
measure resistance EVT-300
between circuit 98EV(-) CPU.
and 98EV(+).
9. Off Disconnect driver display (1227), 73U, Open Go to Locate short to
data link connector (1228). 73V, 73W circuit. next step. ground in circuits
At (1227), measure and 73X to 73U, 73V, 73W
resistance from circuits ground. and 73X, then
73U, 73V, 73W and 73X to repair.
ground.
10. Off Connect a jumper between (1227), <1 ohm. Data link Locate open in
driver display data links circuits 73U, circuits circuits 73U, 73V,
connector (1228). At 73V, 73W check 73W and 73X,
(1227), measure resistance and 73X. good. then repair.
between circuits 73U, 73V, Replace
73W and 73X. driver
display or
EVT-300
CPU.
11. Off Disconnect front antenna (1227), 73B, Open Go to Locate short to
data link connector (1239). 73C, 73D circuit. next step. ground in circuits
At (1227), measure and 73E to 73B, 73C, 73D
resistance from circuits ground. and 73E, then
73B, 73C, 73D and 73E to repair.
ground.
12. Off Connect a jumper between (1227), <1 ohm. Data link Locate open in
front antenna data links circuits 73U, circuits circuits 73U, 73V,
connector (1239). At 73V, 73W check 73W and 73X,
(1227), measure resistance and 73X. good. then repair.
between circuits 73B, 73C, Replace
73D and 73E front
antenna
or
EVT-300
CPU.

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3.18. TESTING TEMPERATURE/COMPASS DISPLAY CIRCUITS

Table 23 Testing Temperature/Compass Display Circuits
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. On Does the Temperature/ Go to Go to next step.
Compass module have a Step 6.
visible display?
2. Off/ Disconnect the 41A to gnd. 12 ± 1.5 Go to Locate cause of
On Temp/Comp display volts. next step. no or low voltage
connector (1282). Turn in circuit 41A, then
ignition on, and measure repair.
voltage from circuit 41A to
ground.
3. On Measure voltage from 41A to 41–G. 12 ± 1.5 Go to Locate open in
circuit 41A to 41–G. volts. next step. circuit 41–G., then
repair.
4. Off Measure voltage from 41B to 12 ± 1.5 Go to Locate cause of
circuit 41B to ground. ground. volts. next step. no or low voltage
in circuit 41B, then
repair.
5. Off With headlights on and 41E to 12 ± 1.5 Power Locate cause of
panel lights all the way ground. volts. circuits no or low voltage
up, measure voltage from check in circuit 41E, then
circuit 41E to ground. good. repair.
Replace
Temp/Comp
module.
6. Off Does the Temp/Comp Display Go to If Temp/Comp
display show a problem shows next step. is not working
receiving data from the problem correctly, replace
temp sensor? with temp the module.
sensor.
7. Off Disconnect temp sensor (1282), 41C Open Go to Locate short to
connector (1284). and 41D to circuit. next step. ground in circuits
At (1282), measure ground. 41C and 41D, then
resistance from circuits repair.
41C and 41D to ground.
8. Off Connect a jumper (1282), <1 ohm. Circuits Locate open in
between temp sensor circuits 41C check circuits 41C and
connector (1284). and 41D. good. 41D, then repair.
At (1282), measure Replace
resistance between temp
circuits 41C and 41D. sensor.

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64 2 CAB ACCESSORIES

Table 23 Testing Temperature/Compass Display Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
9. Off Does the Temp/Comp Display Go to If Temp/Comp
display show a problem shows next step. is not working
receiving data from the problem correctly, replace
compass module? with the module.
compass
module.
10. Off Disconnect compass (1282), 41F, Open Go to Locate short to
module connector (1283). 41H and 41J circuit. next step. ground in circuits
At (1282), measure to ground. 41F, 41H and 41J,
resistance from circuits then repair.
41F, 41H and 41J to
ground.
11. Off Connect a jumper (1282), <1 ohm. Circuits Locate open in
between temp sensor circuits 41F, check circuits 41F, 41H
connector (1283). 41H and 41J. good. and 41J, then
At (1282), measure Replace repair.
resistance between compass
circuits 41F, 41H and 41J. module.

3.19. TESTING ROAD RELAY IV CIRCUITS

Table 24 Testing Road Relay IV Circuits
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
1. On Does the Road Relay IV Go to Go to next step.
module have a visible Step 6.
display?
2. Off/ Disconnect the Road 13PB to gnd. 12 ± 1.5 Go to Locate cause of no
On Relay IV display connector volts. next step. or low voltage in 5A
(662). Turn ignition on, fuse F10–B, circuit
and measure voltage from 13PB, then repair.
circuit 13PB to ground.
3. On Measure voltage from 13PB to 12 ± 1.5 Go to Locate open in
circuit 13PB to 11-GPD. 11-GPD. volts. next step. circuit 11-GPD,
then repair.
4. Off Measure voltage from 14B to 12 ± 1.5 Go to Locate cause of no
circuit 14B to ground. ground. volts. next step. or low voltage in 5A
fuse F10–A, circuit
14B, then repair.

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Table 24 Testing Road Relay IV Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF
POINTS SPEC. SPEC.
5. Off With headlights on and 62EA to 12 ± 1.5 Power Locate cause of no
panel lights all the way ground. volts. circuits or low voltage in
up, measure voltage from check circuit 62EA, then
circuit 62EA to ground. good. repair.
Replace
Road
Relay IV
module.
6. Off Does the Road Relay IV Display Go to If Road Relay IV
display show a problem shows next step. is not working
receiving data from the problem correctly, replace
data link? with data the module.
link.
7. Off Disconnect data link (662), 98D(-) Open Go to Locate short to
pos. connector (514) and and 98E(+) circuit. next step. ground in circuit
data link neg. connector to ground. 98D(-) or 98E(+),
(515). At (662), measure then repair.
resistance from circuit
98D(-) and 98E(+) to
ground.
8. Off Connect a jumper between (662), 98D(-) <1 ohm. Data link Locate open in
data link pos. connector and 98E(+). circuits circuit 98D(-) or
(514), cavity F and data check 98E(+), then repair.
link neg. connector (515), good.
cavity F. At (662), measure Replace
resistance between circuit Road
98D(-) and 98E(+). Relay IV
module.

3.20. TESTING HEATED SEAT-DRIVER

Table 25 Testing Heated Seat-Driver
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Check fuse F10-A for F10-A <1 ohm. Go to next Locate cause of
open condition. step. overload condition,
then repair. Replace
fuse.
2. On With ignition on, measure F10-A, 12 ± 1.5 Go to next Locate cause of no or
voltage to ground at 13EF to volts. step. low voltage in circuits
F10-A and circuit 13EF. gnd. 13EF, 13P, 13H, then
repair.

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Table 25 Testing Heated Seat-Driver (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
3. Off/ Disconnect connector (1331), 12 ± 1.5 Go to next Locate cause of no or
On (1331). Turn ignition on 38A to volts. step. low voltage in circuit
and measure voltage, gnd. 38A, then repair.
circuit 38A from terminal
B to gnd.
4. Off The driver seat heater Driver >100 K Go to next Replace defective
OFF/ON/ HI/LO switch seat ohms. step. driver seat heater
in seat, with switch in heater switch.
OFF position, measure switch A
resistance between and B.
terminals A and B.
5. Off The driver seat heater Driver 100 Go to next Replace defective
OFF/ON/ HI/LO switch seat ohms. step. driver seat heater
in seat, with switch in heater switch.
ON/HI position, measure switch A
resistance between and B.
terminals A and B.
6. Off The driver seat heater Driver 50 ohms. Go to next Replace defective
OFF/ON/ HI/LO switch seat step. driver seat heater
in seat, with switch heater switch.
in ON/LO position, switch A
measure resistance and B.
between terminals A and
B.
7. Off At connector (1331), (1331), 0 ohms. Go to next Locate open or poor
measure resistance, 38-G, step. connection in circuit
circuit 38-G, terminals terminals 38-G to gnd, then
A to gnd. Reconnect A to gnd. repair.
connector (1331).
8. Off Heated seat-driver
circuits check good.

3.21. TESTING HEATED SEAT-PASSENGER

Table 26 Testing Heated Seat-Passenger
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Check fuse F10-A for F10-A <1 ohm. Go to next Locate cause of
open condition. step. overload condition,
then repair. Replace
fuse.

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Table 26 Testing Heated Seat-Passenger (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. On With ignition on, measure F10-A, 12 ± 1.5 Go to next Locate cause of no or
voltage to ground at 13EG to volts. step. low voltage in circuits
F10-A and circuit 13EG. gnd. 13EG, 13P, 13H, then
repair.
3. Off/ Disconnect connector (1332), 12 ± 1.5 Go to next Locate cause of no or
On (1332). Turn ignition on 38B to volts. step. low voltage in circuit
and measure voltage, gnd. 38B, then repair.
circuit 38B from terminal
B to gnd.
4. Off The passenger seat Passenger >100K Go to next Replace defective
heater OFF/ON/ HI/LO seat ohms. step. passenger seat heater
switch in seat, with switch heater switch.
in OFF position, measure switch A
resistance between and B.
terminals A and B.
5. Off The passenger seat Passenger 100 Go to next Replace defective
heater OFF/ON/ HI/LO seat ohms. step. passenger seat heater
switch in seat, with heater switch.
switch in ON/HI position, switch A
measure resistance and B.
between terminals A and
B.
6. Off The passenger seat Passenger 50 ohms. Go to next Replace defective
heater OFF/ON/ HI/LO seat step. passenger seat heater
switch in seat, with heater switch.
switch in ON/LO position, switch A
measure resistance and B.
between terminals A and
B.
7. Off At connector (1332), (1332), 0 ohms. Go to next Locate open or poor
measure resistance, 38-GB, step. connection in circuit
circuit 38-GB, terminals terminals 38-GB to gnd, then
A to gnd. Reconnect A to gnd. repair.
connector (1332).
8. Off Heated seat-passenger
circuits check good.

4. COMPONENT LOCATIONS
B1 Battery Stud.. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . . . . . Power Distribution Panel
B2 Battery Stud.. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . . . . . Power Distribution Panel
(9) Washer Pump.. . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . . . . . Washer Bottle
(20) Horn Connector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Frt Engine Crossmember
(76) Horn (Inline). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Front End Harness at Lower Left, Radiator
(142) Wiper High Speed Delay Relay. . . . . . . . . . . . . . .. . . . . . Power Distribution Panel

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(143) Wiper Low Speed Delay Relay. . . . . . . . . . . . . . .. . . . . . Power Distribution Panel

(167) Owner/Operator Spare Switch. . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(313) Defroster Fan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Front Center Roof
(426) Radio Connector #1. . . .. . . . .. . . .. . . .. . . . .. . . .. .. . . . . . Radio Pigtail to Cab Harness
(428) Roof Connector #2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Right Instrument Panel/Roof Conn. to Cab
Harness
(429) Roof Connector #1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Rt Instrument Panel/Roof Conn. to Cab
Harness.
(430) Wiper Motor Connector. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Wiper Motor
(437) Right Motorized Mirror Switch. .. . .. .. . .. . .. . ... . . . . . At Switch Cluster
(450) Lt Door Courtesy Light. . . . .. . . . . . . .. . . . . . . .. . . .. . . . . . At Switch Cluster
(451) Rt Door Courtesy Light. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(453) Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(454) Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(455) Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(456) Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Center Instrument Panel
(463) R7 Horn Relay. . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . .. . . . . . Power Distribution Panel
(489) Roof Connector #3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Lt Instrument Panel
(494) I1 Ignition Adapter. .. . . . .. . . . .. . . . .. . . . .. . . . .. . .. . . . . . Behind Fuse Panel
(495) I2 Ignition Adapter. .. . . . .. . . . .. . . . .. . . . .. . . . .. . .. . . . . . Behind Fuse Panel
(497) B1 Battery Adapter. .. . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . Behind Fuse Panel
(498) B2 Battery Adapter. .. . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . Behind Fuse Panel
(499) Accessory Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel Right Side
(501) Accessory Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel Right Side
(503) LED Panel Lights Feed Adapter. . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(504) LED Panel Lights Feed Adapter. . . . . . . . . . . . . .. . . . . . Behind Instrument Panel/Switch Breakout
(506) LED Panel Lights Gnd Adapter. . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel/Switch Breakout
(514) Data link Pos... . . . . . . . . .. . . . . . . . .. . . . . . . . . .. . . . .. . . . . . Behind Instrument Cluster
(515) Data link Neg... .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . ... . . . . . Behind Instrument Cluster
(517) Spare Accessory Switch. .. . . . . .. . . . . .. . . . . .. . .. . . . . . At Switch Cluster
(525) CB Radio Connection. . .. . . . . . . . .. . . . . . . . .. . . . .. . . . . . At CB Radio
(528) Right Rear Speaker. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Speaker Pigtail (Inline)
(529) Right Front Speaker.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . At Speaker Pigtail (Inline)
(530) Left Front Speaker. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Speaker Pigtail (Inline)
(531) Left Rear Speaker.. . . . .. . . . . .. . . . .. . . . .. . . . .. . .. . . . . . At Speaker Pigtail (Inline)
(662) Road Relay Display Module Connector. . . . . .. . . . . . Behind Road Relay Display Module
(1039) Driver’s Side Left Window Switch. . . . . . . . . . .. . . . . . In Driver’s Door
(1040) Driver’s Side Right Window Switch. . . . . . . . .. . . . . . In Driver’s Door
(1041) Passenger’s Side Window Switch. . . . . . . . . .. . . . . . Right Door
(1042) Driver Lock Switch. . . .. . . . . . . . . . . . . . . .. . . . . . . .. . . . . . Left Door
(1043) Passenger Lock Switch. . . . . . . . . . . . . . . . . . . . . .. . . . . . Right Door
(1044) Left Power Window Motor. .. . .. .. .. .. .. .. .. ... . . . . . Left Door
(1045) Right Power Window Motor. . . . . . . . . . .. . . . . . .. . . . . . Right Door
(1046) Left Power Lock. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . .. . . . . . Left Door
(1047) Right Power Lock. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Right Door
(1127) Left Mirror Connection. . . . . . .. . . . . . . . . . .. . . . . .. . . . . . Left Door Exterior
(1128) Right Mirror Connection. . . . . . . . . . . . . . . . . . . . . .. . . . . . Right Door Exterior
(1137) Dual Axis Motorized Mirrors.. .. .. .. .. .. .. .. ... . . . . . At Switch Cluster
(1138) Right & Left Electric Window Relay. . . . . . . . .. . . . . . Power Distribution Panel
(1139) Power Lock Relay. .. . .. . . .. . .. . .. . .. . .. . .. . . ... . . . . . Power Distribution Panel
(1140) Power Lock Relay – Unlock. . . .. . . .. . . .. . . .. .. . . . . . Power Distribution Panel
(1156) InterVision Connector. . .. .. . .. . .. .. . .. . .. .. . ... . . . . . Behind InterVision Display
(1158) Driver Right Window Switch. . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster

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(1159) Rt Electric Window Relay. . . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel

(1170) InterVision RS-232 Connector. . . . . . . . . . . . . . .. . . . . . Below Instrument Panel
(1171) Windshield Washer W/Wiper Delay
Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(1226) VORAD CPU Ground Connector. . .. . .. . .. . .. . . . . . On Doghouse Storage Compartment
(1227) VORAD CPU Connector. . . . . . . . . . . . . . . . . . . . .. . . . . . On Doghouse Storage Compartment
(1228) VORAD Driver Display Unit Connector. . . . .. . . . . . On Instrument Wing Panel
(1229) VORAD Right Side Display Unit
Connector. .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . . On A—pillar Panel
(1230) VORAD Harness Connector To Right Side
Sensor. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . . . . On Right Side Cab
(1233A) J1939 VORAD Connector. . . . . . .. . . . . . . . . . .. . . . . . Below Instrument Panel
(1239) VORAD Front Antenna Connector. . . . . . . . . .. . . . . . On Front Bumper
(1240) VORAD Right Side Sensor Connector. . . . .. . . . . . On Right Side Fuel Tank Step
(1281) Temp/Comp Roof Connector. . . . . . . . . . . . . . . .. . . . . . Above Windshield In Roof
(1282) Temp/Comp Display Unit Connector. . . . . . . .. . . . . . Above Windshield
(1283) Compass Module Connector. . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel
(1284) Temp Sensor Connector. . . . . . . . . . . . . . . . . . . . .. . . . . . In Front Engine Compartment
(1331) Driver’s Heated Seat Connector. . . . . . . . . . . .. . . . . . In Driver’s Seat
(1332) Heated Passenger Seat Connector. . . . . . . . .. . . . . . In Passenger Seat

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Figure 5 Instrument Panel Installation Showing Cigar Lighter and Aux. Power Source
1. WING PANEL
2. L.H. INSTRUMENT PANEL
3. AUX. POWER SOURCE LOCATION
4. CIGAR LIGHTER LOCATION
5. INSTRUMENT PANEL SUPPORT RAIL

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Figure 6 Wing Instrument Panel Showing Analog Clock

1. MAIN CAB HARNESS
2. FUSE, 10 AMP AND CIRCUIT 88F
3. INSTRUMENT WIRING, PART OF MAIN CAB HARNESS
4. ANALOG CLOCK GAUGE (526)

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Figure 7 Right Side Only Power Window Wiring

1. DOOR HARNESS
2. (1045), CIR 83C AND 83D
3. (1157), CIR 83C AND 83D
4. RIGHT WINDOW MOTOR
5. (1158), RIGHT WINDOW SWITCH
6. INSTRUMENT WIRING HARNESS
7. CAB HARNESS

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Figure 8 Right Side Only, Power Window Switch and Power Feed
1. FUSE F4–B, 25 AMP
2. ELECTRIC WINDOW RELAY (1159)
3. ELECTRIC WINDOW SWITCH (1158)

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Figure 9 Electric Window/Electric Lock (Right Side Shown) Door Wiring

1. (1049), ELECTRIC LOCK CONNECTOR
2. (1033), ELECTRIC WINDOW CONNECTOR
3. COURTESY LIGHT SWITCH
4. (1041), ELECTRIC WINDOW SWITCH
5. (1043), ELECTRIC LOCK SWITCH
6. (1047), RIGHT POWER LOCK
7. COURTESY LIGHT
8. (1045), RIGHT WINDOW MOTOR

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Figure 10 Electric Windows, Power Wiring

1.(1033), ELECTRIC WINDOW RIGHT DOOR CONNECTOR
2. (497), B1 BATTERY ADAPTER CONNECTOR
3. (499), A1 ACCESSSORY ADAPTER
4. (1138), ELECTRIC WINDOW RELAY
5. (503), PANEL LIGHTS FEED ADAPTER
6. (455), GROUND ADAPTER
7. (1034), ELECTRIC WINDOW LEFT DOOR CONNECTOR
8. LEFT COURTESY LIGHT & DOOR SWITCH CONNECTOR
9. ELECTRIC WINDOW HARNESS
10. FUSE F4–B, 20A
11. RIGHT COURTESY LIGHT & DOOR SWITCH CONNECTOR

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Figure 11 Electric Lock, Power Wiring

1. (1049), ELECTRIC LOCK RIGHT DOOR CONNECTOR
2. (497), B1 BATTERY ADAPTER CONNECTOR
3. FUSE F1–A, 10A
4. (1140), POWER LOCK RELAY-UNLOCK
5. (1139), POWER LOCK RELAY
6. (456), GROUND ADAPTER
7. (503), PANEL LIGHTS FEED ADAPTER
8. (1048), ELECTRIC LOCK LEFT DOOR CONNECTOR
9. LEFT COURTESY LIGHT & DOOR SWITCH CONNECTOR
10. ELECTRIC LOCK HARNESS
11. RIGHT COURTESY LIGHT & DOOR SWITCH CONNECTOR

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Figure 12 Windshield Wiper/Washer Wiring

1. CHASSIS HARNESS
2. WASHER BOTTLE
3. (3), DASH PANEL CONNECTOR
4. POWER DISTRIBUTION CENTER
5. TO WIPER/WASHER SWITCH
6. TO POWER DISTRIBUTION CENTER
7. WASHER HARNESS

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Figure 13 Wiper Motor and Connector

1. TO POWER DISTRIBUTION CENTER (THROUGH ENGINE HARNESS)
2. WIPER MOTOR

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Figure 14 Wiper Switch Wiring

1. SWITCH PANEL
2. WIPER/WASHER SWITCH (1171)
3. MAIN CAB WIRING

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Figure 15 Wiper Wiring at Power Distribution Center

1. (143), WIPER-HIGH SPEED DELAY RELAY
2. (142), WIPER-LOW SPEED DELAY RELAY
3. TO CAB WIRING
4. TO CAB WIRING
5. FUSE F4–D, 15A

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Figure 16 Horn Wiring at Power Distribution Center

1. (B1), BATTERY STUD
2. (B2), BATTERY STUD
3. FUSE F-5C, 15A
4. HORN RELAY (463–R7)

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Figure 17 Horn Button Assembly (Slip Ring)

1. CIRCUIT 85C
2. MAIN CAB WIRING HARNESS
3. CIRCUIT 85C
4. HORN BUTTON ASSEMBLY

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Figure 18 Horn Installation

1. STANDARD ELECTRIC HORN, HIGH NOTE
2. OPTIONAL ELECTRIC HORN, LOW NOTE
3. ENGINE FRONT MOUNTING BRACKET
4. ENGINE FRONT CROSSMEMBER
5. LEFT SIDE MEMBER
6. (76), CIRCUITS 85B AND 85–G

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Figure 19 Heated, Lighted, and Motorized Mirror (Right Door Shown)

1. HEATED, LIGHTED AND MOTORIZED MIRROR
2. (1128) MIRROR CONNECTOR
3. ANTENNA CONNECTOR

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Figure 20 Power Circuits for Heated, Lighted, and Motorized Mirrors

1. (973) MIRROR POWER CONNECTOR
2. (437) RIGHT MOTORIZED MIRROR SWITCH
3. (1054) RIGHT DOOR COURTESY LIGHT AND MIRROR CONNECTION
4. (1116) MIRROR LIGHTS CONNECTOR
5. (456) GROUND ADAPTER
6. (504) PANEL LIGHT FEED ADAPTER
7. (1050) LEFT DOOR COURTESY LIGHT AND MIRROR CONNECTION

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Figure 21 Power Circuits for Dual Axis Mirrors

1. (973) MIRROR POWER CONNECTOR
2. (1137) DUAL AXIS MOTORIZED MIRROR SWITCH
3. (1054) RIGHT DOOR COURTESY LIGHT AND MIRROR CONNECTION
4. (456) GROUND ADAPTER
5. (1050) LEFT DOOR COURTESY LIGHT AND MIRROR CONNECTION

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Figure 22 CB Radio Accommodation Wiring

1. (525) CB RADIO POWER CONNECTION
2. CB ANTENNA CONNECTION
3. CB SPEAKER CONNECTION
4. CB SPEAKER
5. LEFT DOOR ANTENNA CONNECTION
6. ANTENNA MULTIPLEXER
7. RIGHT DOOR ANTENNA CONNECTION

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Figure 23 Entertainment Radio Wiring

1. ENTERTAINMENT RADIO
2. RIGHT REAR SPEAKER
3. RIGHT FRONT SPEAKER
4. LEFT FRONT SPEAKER
5. LEFT REAR SPEAKER
6. ANTENNA MULTIPLEXER
7. RADIO CONNECTOR #1 (426)
8. ROOF CONNECTOR #2 (428)
9. ROOF CONNECTOR #3 (489)
10. RADIO CONNECTOR #2 (427)
11. ANTENNA CONNECTOR

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Figure 24 InterVision Wiring

1. TO FUSE F10–A
2. INTERVISION DISPLAY MODULE
3. (1156) INTERVISION DISPLAY MODULE CONNECTION
4. INTERVISION HARNESS

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Figure 25 InterVision RS-232 Wiring

1. TO INTERVISION DISPLAY MODULE
2. (1170) RS-232 CONNECTOR

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Figure 26 Owner Operator Spare Switch

1. RELAY (167)
2. FUSE F10–A
3. (517) OWNER/OPERATOR SPARE SWITCH
4. INSTRUMENT WIRING HARNESS

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Figure 27 EATON VORAD Collision Avoidance EVT-300 Circuits — Front Antenna

1. EATON VORAD SPEED SENSOR TRANSMITTER — FRONT ANTENNA
2. FRONT ANTENNA WIRING HARNESS

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Figure 28 EATON VORAD Collision Avoidance EVT-300 Circuits — Side Sensor W/51”, 72” Pro Sleeper
1. EATON VORAD — SIDE SENSOR
2. SIDE SENSOR WIRING HARNESS

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Figure 29 EATON VORAD Collision Avoidance EVT-300 Circuits — Side Sensor W/Daycab
1. EATON VORAD — SIDE SENSOR W/PAINTED STEPS
2. SIDE SENSOR WIRING HARNESS
3. EATON VORAD — SIDE SENSOR W/ALUMINUM STEPS

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Figure 30 EATON VORAD Collision Avoidance EVT-300 Circuits — Side Sensor Chassis Skirt
1. CHASSIS SKIRT
2. EATON VORAD — SIDE SENSOR
3. SIDE SENSOR WIRING HARNESS

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Figure 31 EATON VORAD Collision Avoidance EVT-300 Circuits — Driver Display Unit
1. EATON VORAD COLLISION AVOIDANCE DRIVER DISPLAY/CONTROL ELECTRONIC
CONTROL
2. INSTRUMENT PANEL

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Figure 32 EATON VORAD Collision Avoidance EVT-300 Circuits — Side Display Unit
1. A-PILLAR TRIM COVER
2. EATON VORAD SIDE DISPLAY MODULE INSTRUMENT

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Figure 33 EATON VORAD Collision Avoidance EVT-300 Circuits — CPU

1. LOWER COVER CONSOLE PANEL
2. EATON VORAD COLLISION AVOIDANCE CPU ELECTRONIC CONTROL
3. ARROW C, SEE NEXT FIGURE
4. CENTER CONSOLE INSTRUMENT PANEL

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Figure 34 EATON VORAD Collision Avoidance EVT-300 Circuits — CPU

1. EATON VORAD MAIN WIRING HARNESS
2. EATON VORAD GROUND JUMPER HARNESS
3. VIEW IN DIRECTION OF ARROW C
4. CENTER CONSOLE INSTRUMENT PANEL

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Figure 35 EATON VORAD Collision Avoidance EVT-300 Circuits — Wiring Harness

1. EATON VORAD SIDE DISPLAY MODULE INSTRUMENT
2. A-PILLAR
3. EATON VORAD COLLISION AVOIDANCE DRIVER DISPLAY/CONTROL ELECTRONIC
CONTROL
4. INSTRUMENT PANEL
5. EATON VORAD MAIN WIRING HARNESS
6. EATON VORAD CAB SIDE SENSOR WIRING HARNESS CONNECTOR
7. FRONT END WIRING HARNESS CONNECTOR
8. CENTER CONSOLE INSTRUMENT PANEL
9. EATON VORAD COLLISION AVOIDANCE CPU WIRING HARNESS CONNECTOR

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Figure 36 EATON VORAD Collision Avoidance EVT-300 Circuits — Side Sensor Wiring Harness
W/51” Pro Sleeper
1. EATON VORAD SLEEPER BOX SIDE SENSOR WIRING HARNESS CONNECTOR
2. EATON VORAD SLEEPER BOX WIRING HARNESS
3. EATON VORAD CAB SIDE SENSOR WIRING HARNESS CONNECTOR

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Figure 37 EATON VORAD Collision Avoidance EVT-300 Circuits — Side Sensor Wiring Harness
W/Daycab
1. EATON VORAD CAB SIDE SENSOR WIRING HARNESS CONNECTOR
2. EATON VORAD CAB WIRING HARNESS
3. TRAILER SOCKET
4. EATON VORAD CAB SIDE SENSOR WIRING HARNESS CONNECTOR

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Figure 38 EATON VORAD Collision Avoidance EVT-300 Circuits — Side Sensor Wiring Harness
W/72” Pro Sleeper
1. EATON VORAD SLEEPER BOX SIDE SENSOR WIRING HARNESS CONNECTOR
2. EATON VORAD SLEEPER BOX WIRING HARNESS

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Figure 39 Temperature/Compass Cab Wiring Harness

1. COMPASS MODULE SENSOR GAUGE
2. CAB OUTSIDE TEMPERATURE SENSOR INSTRUMENT WIRING HARNESS
3. FRONT END CONNECTOR
4. CAB BASE HARNESS

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Figure 40 Temperature/Compass Wiring Harness

1. COMPASS MODULE SENSOR GAUGE
2. ROOF HARNESS
3. CAB OUTSIDE TEMPERATURE SENSOR INSTRUMENT WIRING HARNESS
4. CAB BASE HARNESS

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Figure 41 Temperature/Compass Temp Sensor Wiring Harness

1. OUTSIDE TEMPERATURE SENSOR GAUGE — CIRCUITS 41C & 41D
2. FRONT END WIRING HARNESS

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Figure 42 Temperature/Compass Display

1. ROOF WIRING HARNESS
2. TEMPERATURE/COMPASS DISPLAY MODULE

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Figure 43 Road Relay IV Wiring Harness Driver Display Unit

1. CIRCUITS 14B & 13PB
2. CIRCUIT 14B TO (497) B1 BATTERY ADAPTER
3. CIRCUIT 13PB TO (495) I2 IGNITION ADAPTER
4. 5 AMP FUSES F10–A & F10–B
5. CAB BASE HARNESS
6. CIRCUIT 11–GPD TO (453) GROUND ADAPTER
7. CIRCUIT 62EA TO (504) LED PANEL LIGHTS FEED ADAPTER
8. ROAD RELAY IV ELECTRICAL HARNESS
9. CIRCUIT 98D(-) TO (515) DATA LINK NEG.
10. CIRCUIT 98E(+) TO (514) DATA LINK POS.

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Figure 44 Road Relay IV Wiring Harness Driver Display Unit

1. ROAD RELAY IV ROOF WIRING HARNESS TO CONNECTOR (662)
2. CUMMINS ROAD RELAY IV ENGINE MONITORING DISPLAY ELECTRONIC GAUGE
3. CAB ROOF HARNESS
4. CAB BASE HARNESS
5. ROAD RELAY IV ELECTRICAL HARNESS
6. ROAD RELAY IV POWER (662M) TO CONNECTOR (662F) ROOF WIRING HARNESS

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Figure 45 Road Relay IV Wiring Harness Driver Display Unit

1. ROAD RELAY IV ROOF WIRING HARNESS TO CONNECTOR (662)
2. CUMMINS ROAD RELAY IV ENGINE MONITORING DISPLAY ELECTRONIC GAUGE

Figure 46 Heated Seat-Driver/Passenger

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Table of Contents

1. DESCRIPTION. . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . ..113
1.1. BATTERY POWER. . .. .. .. .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. ..113
Remote Start Terminal.. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . .113
1.2. CHARGING CIRCUITS. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . ..113
With 3+1 Isolated Battery System.. . .. .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . ..113
1.3. CRANKING MOTOR CIRCUITS.. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. ..113
Cranking Motor. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . ..113
Cranking Motor Circuits. .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. .113
Cranking Motor Thermal Overcrank Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .113

2. OPERATION.. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. ..114
2.1. BATTERY POWER. . .. .. .. .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. ..114
Remote Start Terminal.. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . .114
2.2. CHARGING CIRCUITS. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . ..114
With 3+1 Isolated Battery System.. . .. .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . ..114
2.3. CRANKING MOTOR CIRCUITS.. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. ..114
Cranking Motor. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . ..114
Cranking Motor Circuits. .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. .114
Cranking Motor Thermal Overcrank Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .115

3. TROUBLESHOOTING. . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. .115
3.1. BATTERIES AND CABLES.. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. ..115
Battery Test Procedure. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..116
Battery Cable Voltage Loss Test. . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . .117
3.2. STARTING MOTOR SYSTEM CIRCUITS AND COMPONENTS. . . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . . ..119
Starter Solenoid Circuit Test - Part 1. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . .. . .119
Starter Solenoid Circuit Test - Part 2. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .120
Starter Magnetic Switch Circuit Test - Part 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122
Starter Magnetic Switch Circuit Test - Part 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123
Starter Motor Replacement Test. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .124
Testing Thermal Overcrank Protection System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . .125
3.3. VEHICLE CHARGING SYSTEM. . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .126
Batteries Undercharged. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . .126
Alternator Tests. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .127
Alternator Wiring Test.. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. .127
Alternator Replacement Test — Voltage Output Test. .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .128
Alternator Replacement Test — Amperage Output Test. . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .129
Alternator Replacement Test — Replacement. . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . .130

4. COMPONENT LOCATIONS. .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .130

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1. DESCRIPTION
1.1. BATTERY POWER
The vehicle batteries, connected in parallel, provide power via the positive battery cable which is connected
to the cranking motor solenoid "B" terminal. Depending upon battery box location, some vehicles have two
positive cables to the cranking motor.

The negative battery terminals are connected to the cranking motor ground terminal, which is connected to the
frame rail. The engine and cab are also connected by ground cables to the cranking motor ground.

An optional 3+1 isolated battery system is available. Refer to POWER DISTRIBUTION AND GROUND
SYSTEM section for discussion about this system.

Remote Start Terminal

An optional remote start terminal allows an external battery power source to either charge the vehicle batteries
or assist in cranking the engine.

1.2. CHARGING CIRCUITS

The Delco 22-SI, 12 volt, 100-ampere capacity alternator is standard on this family of vehicles. Other
alternators are available as options.

The alternator output "B" terminal is connected to the start magnetic switch “B” terminal and to the crank
motor solenoid “B” terminal.

With 3+1 Isolated Battery System

On vehicles with this system, 7 volt output from the alternator “R” terminal is used to energize the isolated
battery magnetic switch whenever the alternator is operating. (Refer to the POWER DISTRIBUTION AND
GROUND SYSTEM section for information on the 3+1 system.)

1.3. CRANKING MOTOR CIRCUITS

Cranking Motor

The Delco MT–41 Series cranking motor is used with the standard engine in the 5000i series truck, and the
Delco MT–42 series cranking motor is standard for the 9000i series vehicles. It provides the rotation of the
engine crank via the flywheel needed to start the engine.
Cranking Motor Circuits

The cranking motor circuits provide power to the cranking motor to turn over the crankshaft of the engine. If all
other systems are operational, the engine will start.

Cranking Motor Thermal Overcrank Protection

On vehicles with thermal overcrank protection (optional system), excessive cranking will cause cranking motor
temperature to reach a pre-set thermal overcrank limit, and the thermal switch will open causing the motor
to dis-engage. This protects the starting motor from heat damage. When the crank motor cools, the switch
closes permitting the crank motor to operate again.

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2. OPERATION
Refer to CHARGING AND CRANKING circuit diagrams in CTS-5298 or S08225.

2.1. BATTERY POWER

Vehicle batteries are connected in parallel with the positive battery cable connected to the cranking motor
solenoid "B" terminal. Depending upon battery box location, some vehicles have two positive cables to the
cranking motor. The additional cable reduces the voltage drop during cranking.

The negative battery terminals are connected to the cranking motor ground terminal, which is connected to the
frame rail. The engine and cab are also connected by ground cables to the cranking motor ground.

An optional 3 +1 isolated battery system is available. Refer to POWER DISTRIBUTION AND GROUND
SYSTEM for this system.

Remote Start Terminal

The remote starter terminal allows an external battery power source to either charge the vehicle batteries or
assist in cranking the engine. Connect the external source positive cable to the remote start terminal and the
external source negative cable to vehicle frame rail.

To use an external power source to charge the deep cycle battery (with 3+1 system) at the same time as the
cranking batteries, a jumper must be used to connect the positive deep cycle battery terminal to the positive
terminal of the cranking batteries.

2.2. CHARGING CIRCUITS

The Delcotron Integral Charging systems are high-output alternators, with an internal diode rectifier and
voltage regulator, producing direct current (DC) to operate vehicle electrical system and charge vehicle
batteries. The Delco 22-SI alternator (100A, 115A or 145A) uses brushes and slip rings.

The alternator output “B” terminal is connected to the start magnetic switch “B” terminal and to the crank
motor solenoid “B” terminal.

For a complete discussion on operating principles for alternators, refer to GROUP 08 - ELECTRICAL in the
CTS-5000 Master Service Manual for the specific alternator being serviced.

With 3+1 Isolated Battery System

On vehicles with this system, 7 volt output from the alternator “R” terminal is used to energize the isolated
battery magnetic switch whenever the alternator is operating. (Refer to POWER DISTRIBUTION AND
GROUND SYSTEM section for the 3+1 system.)

2.3. CRANKING MOTOR CIRCUITS

Cranking Motor

For complete information on operation and servicing this cranking motor and optional cranking motors used on
these vehicles, refer to GROUP 08 - ELECTRICAL in the CTS-5000 Master Service Manual.
Cranking Motor Circuits

With the key in the start position, ignition voltage from start feed adapter (509) is applied through circuit 17B
to energize the starter magnetic switch.

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 3 BATTERY, CHARGING AND CRANKING SYSTEMS 115

Battery power from the (B1) battery stud (circuit 14A) is always present at the “B” terminal of the magnetic
switch. With the start magnetic switch energized, battery power is applied through circuit 17C to energize the
crank motor solenoid.

With the crank motor solenoid energized, the solenoid engages the cranking motor and battery power causes
the motor to rotate. When the starter switch is released, a spring returns the solenoid to the released position.

Cranking Motor Thermal Overcrank Protection

On vehicles with thermal overcrank protection (optional system), the start magnetic switch control coil ground
circuit 17D is connected to the normally closed thermal switch (275). The thermal switch is located in the end
of the cranking motor. The thermal switch is grounded at the engine ground stud.

If excessive cranking causes cranking motor temperature to reach pre-set thermal overcrank limits, the
thermal switch opens causing the start magnetic switch to de-energize, turning off power to the cranking motor
solenoid S terminal, dis-engaging the cranking motor.

When the crank motor cools, the switch closes permitting the crank motor to operate again.

3. TROUBLESHOOTING
Refer to CHARGING AND CRANKING circuit diagrams in CTS-5298 or S08225.

A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 -
ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit, by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not
covered in detail. It is assumed that the technician knows to check for a malfunctioning switch,
relay, or solenoid.

3.1. BATTERIES AND CABLES

The standard battery system for 5000 and 9000 conventionals consists of three 12V maintenance free
batteries. All optional batteries installed are also maintenance free.

WARNING – When handling batteries, always wear face or eye protection, have water supply
available, assure good ventilation, and be sure no open flames are present.

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 116 3 BATTERY, CHARGING AND CRANKING SYSTEMS

Battery Test Procedure

Battery Test Configuration Figure below.

Test each battery separately.

1. Disconnect both battery terminals at each battery. Check each battery visually.

2. Examine the hydrometer eye (if no eye go to next step).

a. Eye shows green - go to step 4.
b. Eye shows dark - recharge, then go to step 3.
c. Eye shows yellow - replace battery.

3. Apply a 300A load for 15 seconds. Turn off load and wait one minute.
a. If 12.4V or more - go to step 4.
b. If less than 12.4V - recharge then repeat step 3.

4. Apply a test load equal to 50% of the battery CCA rating at 0°F (-18°C). After 15 seconds,with the load
still applied, measure and record terminal voltage ________. Turn the load off.

5. Estimate the battery temperature. If measured voltage does not meet or exceed the value shown in
the following table, replace the battery.

Table 27 Battery Temperature Table

Temp. 70°F / 21°C 50°F / 10°C 30°F / –1°C 15°F / –9°C 0°F / –18°C
Min. Volts 9.6V 9.4V 9.1V 8.8V 8.5V

6. Clean all cable ends and terminals of the battery with a wire brush.

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Figure 47 Battery Test Configuration

Battery Cable Voltage Loss Test

Refer to Battery Cable Voltage Loss Test Figure below.

Slow cranking is often caused by high resistance in the battery cables or connections, especially in cold
weather. After all batteries check good (Battery Test Procedure) and terminals are clean and tight, check the
battery cables. To do this place a specific load on the batteries at the starter. This load will be supplied
by the adjustable carbon pile.

The voltage drop in the positive cable plus the voltage drop in the negative cable equals the difference
between the battery voltage and the starter voltage due to the cables. The maximum acceptable loss has been
calculated only for the specific load specified in the test.

1. Tighten nuts holding battery cables to the solenoid and starter terminals.

NOTE – The solenoid BAT terminal is at battery voltage when batteries are connected.

2. Connect carbon pile positive lead to start solenoid “B” terminal and negative lead to starter ground terminal
(Battery Cable Voltage Loss Test Figure).

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118 3 BATTERY, CHARGING AND CRANKING SYSTEMS

3. Connect voltmeter from the starter solenoid “B” terminal to battery positive post.

4. Adjust load to 500A, quickly read and record positive cable voltage. Turn off the load and allow carbon
pile to cool.

5. Connect voltmeter from negative battery post to starter ground terminal. Attach ground lead directly to
stud and not the cable end.

6. Adjust load to 500A, read and record negative cable voltage. Turn off the load.

Positive Cable Voltage Loss (step 4) ________

plus Negative Cable Voltage Loss (step 6) ________

equals Total Cable Loss ________.

If system loss is 0.6V or less, go to STARTING MOTOR SYSTEM CIRCUITS AND COMPONENTS.

If system loss is greater than 0.6V, repair or replace cable(s) with excessive voltage loss and retest.

Figure 48 Battery Cable Voltage Loss Test

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 3 BATTERY, CHARGING AND CRANKING SYSTEMS 119

To check the interconnecting cables between the batteries, while cranking, measure the terminal voltage of
each battery by touching voltmeter leads to the post of each battery (refer to the Figure below).

If the difference between any two battery readings in the same battery box is more than 0.5 volt or any cable is
warm to the touch, replace the interconnecting cables.

Figure 49 Measure Terminal Voltage of Each Battery

3.2. STARTING MOTOR SYSTEM CIRCUITS AND COMPONENTS

Starter Solenoid Circuit Test - Part 1

Starter shifting in and out, or not pulling in, is often caused by high resistance in the starter solenoid circuit.
When the solenoid circuit has excessive voltage loss, the starter pinion sometimes may not engage the
flywheel. If it does engage, it may drop out too soon when battery voltage drops. The solenoid circuit includes
the starter magnetic switch and leads connected to the starter solenoid.

On vehicles with overcrank protection, refer to Testing Thermal Overcrank Protection System before
performing this test.

1. Disconnect circuit 17C from the starter solenoid “S” terminal. Connect the carbon pile positive lead to
circuit 17C and negative lead to the starter ground. Connect the voltmeter positive lead to the solenoid
battery stud and the negative lead to the starter motor ground stud (not to carbon pile clamp).

2. Have an assistant push the start button or turn key switch. The magnetic switch should energize with a
clicking sound. If the switch doesn’t "click," either the switch is defective (refer to Starter Magnetic Switch
Circuit Test) or there is no voltage from the key switch circuit.

3. Adjust the carbon pile to 100 amp load. Measure and record cable voltage. Release the start button or
key switch. If the reading is more than .5 volt lower than the value shown in the table in Battery Test
Procedure, perform that test and Battery Cable Voltage Loss Test.

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120 3 BATTERY, CHARGING AND CRANKING SYSTEMS

4. Move the voltmeter negative lead from the starter motor ground stud to the end of circuit 17C that is
connected to the carbon pile. Do not connect to carbon pile clamp.

5. Push and hold the start button again and re-adjust the carbon pile load to 100 amps. Read and record
voltage to the solenoid. Release the start button or key switch.

Cable Voltage (step 3) ________

minus Solenoid Voltage (step 5) ________

equals Circuit Loss = ________

If circuit loss is 1.0 volt or less, go toStarter Magnetic Switch Circuit Test - Part 1.

If circuit loss is more than 1.0 volt, go toStarter Solenoid Circuit Test - Part 2.

Figure 50 Starter Solenoid Circuit Test — Part 1

Starter Solenoid Circuit Test - Part 2

If the voltage loss in Test 1 was more than 1 volt, the loss is excessive. The loss may be from loose terminals,
corrosion, or a worn out start magnetic switch. To locate the problem:

1. Leave carbon pile connected as in Part 1.

2. Connect DMM positive lead to solenoid BAT stud and negative lead to large terminal of magnetic switch. If
voltage shows on meter, move meter lead to the other large magnetic switch terminal.

3. Push start button with key on or turn key switch to start position. Turn on and adjust carbon pile to 100
amp load. Read and record first wire voltage loss. Release start switch.

4. Connect DMM positive lead to other (opposite) large terminal on magnetic switch and negative lead to
circuit 17C (not to carbon pile clamp).

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 3 BATTERY, CHARGING AND CRANKING SYSTEMS 121

5. Push start button or turn key switch to start position. Turn on and adjust carbon pile to 100 amp load.
Read and record second wire voltage loss. Release start switch.

First Wire Loss (step 3) ________

plus Second Wire Loss (step 5) ________

equals Total Wiring Loss = _________(0.8V maximum loss)

If circuit loss is 0.8 volt or less, go to step 6.

If circuit loss is more than 0.8 volt, repair or replace wire, then go to step 6.

6. Connect DMM across the two large magnetic switch terminals (battery voltage will show immediately).

7. Push start button or turn key switch to start position. Turn on and adjust carbon pile to 100 amp load.
Read and record ________ voltage loss across the magnetic switch.

8. If the voltage drop is greater than 0.2 volt, replace the magnetic switch.

9. Remove carbon pile. Leave circuit 17C disconnected (use tape to insulate) to perform Starter Magnetic
Switch Circuit Test - Part 1 (below).

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Figure 51 Starter Solenoid Circuit Test - Part 2

Starter Magnetic Switch Circuit Test - Part 1

A magnetic switch that does not close or drops out too soon can be caused by high resistance or an open in
the control circuit.

1. Disconnect circuit 17C from start solenoid “S” terminal and insulate with tape. Connect voltmeter positive
lead to the starter solenoid BAT stud and negative lead to the starter motor ground stud.

2. Have an assistant push the start button (with key on) or turn key to start position.You should hear the
magnetic switch relay “click." If not, proceed anyway. Read and record battery cable voltage. Release
start switch.

3. Connect the voltmeter positive lead to the small magnetic switch terminal and the negative lead to the
switch ground screw. (Magnetic switch is internally grounded through the mounting.)

4. Have an assistant push the start button (with key on) or turn key to start position. Read and record
magnetic switch voltage. Release the start switch.

Battery Cable Voltage (step 2) ________

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 3 BATTERY, CHARGING AND CRANKING SYSTEMS 123

minus Magnetic Switch Voltage (step 4) ________

equals Control Circuit Wiring Loss = ________

If circuit loss is 1.0 volt or less and the magnetic switch closes, circuit is OK.

If circuit loss is 1.0 volt or less and the magnetic switch doesn’t close, replace the switch and repeat the test.

If circuit loss is more than 1.0 volt, go to Starter Magnetic Switch Circuit Test - Part 2 (below).

Figure 52 Starter Magnetic Switch Circuit Test - Part 1

Starter Magnetic Switch Circuit Test - Part 2

If Starter Magnetic Switch Circuit Test - Part 1 has shown a voltage loss greater than 1.0V, perform this test
using a digital multimeter (DMM). Leave circuit 17C disconnected from the starter solenoid.

1. With the key on and start button depressed or key switch in start position, and the voltmeter leads in the
positions shown for each step:
a. Measure magnetic switch to starter motor ground. If reading is within 1.0 volt of battery voltage, repair
magnetic switch ground. If reading is not within 1.0 volt of battery voltage, go to Step B.
b. Measure and record ______ solenoid to key voltage.
c. Measure and record ______ key switch voltage.
d. Measure and record ______ key to start button voltage.
e. Measure and record ______ start button voltage.
f. Measure and record ______ start button to magnetic switch voltage.

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124 3 BATTERY, CHARGING AND CRANKING SYSTEMS

TOTAL ______ (1.0V MAX. ALLOWED)

If greater than 1.0 volt, repair or replace any circuit or component with excess voltage loss.

If any of the circuits or component checks (B through F) show full battery voltage with the start button
depressed or key switch in start position, then an open circuit exists in the portion of the circuit between the
DMM leads. Repair that portion and connect circuit 17B to the starter solenoid.

Figure 53 Starter Magnetic Switch Circuit Test - Part 2

Starter Motor Replacement Test

A. Cold Weather Start Magnetic Switch Problems

If all previous battery tests have been performed, the vehicle batteries and starter wiring have
been checked.

The starter magnetic switch can fail to "hold in" during cold weather cranking due to low voltage,
even though the switches and circuits check OK. With this failure you will hear the starter failing to
stay engaged with the flywheel. It is caused by low system voltage releasing the magnetic switch.

If this condition exists, have an assistant clamp a heavy battery jumper cable between the two
big (5/16") studs on the magnetic switch while cranking. Caution - The studs are battery
voltage and the engine should crank when the jumper is connected. Remove jumper to
stop cranking. If the engine cranks properly with jumper in place, replace the magnetic switch
and make sure starter mounting bolts are tight.
B. Checking Available Voltage At Starter

If all previous battery tests have been performed, the vehicle batteries and starter wiring have
been checked, but the engine still cranks slowly, check available voltage at the starter.

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 3 BATTERY, CHARGING AND CRANKING SYSTEMS 125

1. While cranking engine, measure voltage between the starter BATT terminal and starter ground.
a. If voltage is 9.0 volts or more, the problem must be in the starter (or engine). Replace the starter.
b. If the voltage is less than 9.0 volts, go to Battery Cable Voltage Loss Test.

2. Check the interconnecting cable between the batteries.

Figure 54 Starter Motor Replacement Test

Testing Thermal Overcrank Protection System

Table 28 Testing Thermal Overcrank Protection System

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (275) Thermal <2 ohms. Go to next Replace the thermal
from thermal switch switch, step. switch.
and measure resistance across
across switch terminals terminals.
(engine must be cool).
2. On With key in start position, (275), 17B 12± 1.5 Go to next Go to Starter Solenoid
at connector (275) to gnd. volts. step. Circuit Test - Part 1.
measure voltage to gnd.
at circuit 17B.

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Table 28 Testing Thermal Overcrank Protection System (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
3. On With key in start (275), 17B 12± 1.5 Go to next Repair open in circuit
position, at connector to 17-G. volts. step. 17-G.
(275) measure voltage
between circuits 17B and
17-G.
4. Off Thermal overcrank
circuits check good.

3.3. VEHICLE CHARGING SYSTEM

Batteries Undercharged

Before beginning test procedures: check battery cables and alternator wiring (especially grounds) for clean,
tight connections. Wires and connectors should not be damaged or corroded.

Perform the following checks before removing the alternator from the vehicle.

1. Accessories having been left on for an extended time.

2. Check alternator drive belt tension (refer to GROUP 12 - ENGINE, Cooling in the CTS-5000 Master
Service Manual for belt tension specifications). As a general rule, if the alternator fan can be rotated by
pulling on the fan with one finger, the belt is too loose.

3. Inspect for defective batteries as described in GROUP 08 - ELECTRICAL, Battery Section in the
CTS-5000 Master Service Manual.

4. Wiring defects. Visually check wiring, clamps, and connections for clean, tight connections, free of
damage and corrosion.

5. With the engine OFF, check voltage to ground at the BAT terminal of the alternator. A zero reading
indicates an open in circuit 2, between the alternator and batteries.

6. A defective component or wiring defect may be causing a small current drain that is less than the fuse
rating for the circuit so the fuse does not open. To locate the unwanted current drain:

NOTE – Batteries should be fully charged for the following test.

a. KEY OFF- Turn all accessories and controls off. Disconnect circuit 2 from the alternator B terminal.
b. To check the entire system for current drains, insert the DMM leads in the COM and 10A fused jack on
the meter. Set the meter to DC Amps. Connect the meter in series with the alternator (if the meter
leads are not connected with correct polarity, a (-) amp reading will be present.
c. Some current draw will be present. If the current draw is less than 0.3A move the lead from the 10A
jack to the 320mA jack to read the exact current flow.
d. Refer to the Battery Power Distribution circuit diagrams in CTS-5298 or S08225. Remove the battery
feed fuses one at a time, while monitoring the meter for any change in current flow. Note that some
circuits (such as clock or radio or engine computer, etc.) should be drawing some current. Look for
current draw in circuits that should not be active.

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7. Perform Alternator Wiring Test.

Alternator Tests

The alternator output must reach the batteries and accessory loads with a minimum amount of voltage loss.
Any loss slows the rate of charge to the batteries and can cause the batteries to be undercharged. Discharged
batteries can damage the starter and cause vehicle electrical components to operate improperly.

Most alternators control the maximum system voltage using a voltage regulator. Maximum voltage output
is available at the alternator BAT terminal, but if any voltage is lost in the wiring, something less than the
maximum will reach the batteries and load devices. The greatest losses occur when the charging system
is outputting at the maximum rated level (amps).

Alternator Wiring Test

Instead of using alternator current output this test uses the same amount of current but draws it from the
batteries (must be fully charged). Using the carbon pile load, the current flows in reverse through the circuit
without the engine running.

1. Without the engine running, connect the carbon pile to the alternator output terminal and ground.

NOTE – Alternator output is at battery voltage.

2. Connect voltmeter between alternator output terminal and positive battery terminal.

3. Adjust the carbon pile to alternator rated output (amps). Rated output is stamped on the case or on a tag.

4. Read voltmeter and record positive circuit voltage loss. Immediately turn the carbon pile off.

5. Move the voltmeter connections to between the alternator, ground and negative battery terminal. Adjust
carbon pile to rated output (amps) of the alternator.

6. Read voltmeter and record negative circuit voltage loss. Immediately turn carbon pile off.

Positive Circuit Loss Voltage (step 4) ________

plus Negative Circuit Loss Voltage (step 6) ________

equals System Loss ________

If system loss is 0.7V or less, go toAlternator Replacement Test

If system loss is greater than 0.7V, repair circuit(s) with excessive voltage loss and retest. Then go to
Alternator Replacement Test.

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Figure 55 Alternator Wiring Test

Alternator Replacement Test — Voltage Output Test

If the wiring tests have been performed (circuits OK), adjust alternator belt and tighten mounting bolts and
ground connections. Batteries must be near full charge with more than 12.4 volts no load voltage.

Voltage Output Test

1. With vehicle at shop temperature, connect voltmeter between alternator “B” (+) and “G” (-) terminals.

2. With NO electrical loads turned on, start the engine. Fast idle engine until voltage stabilizes (does not
increase) for 2 minutes.

3. Check and record alternator output voltage _______V (should not exceed 15.5 volts).

4. If voltage reading is above 15.5V, replace the alternator.

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Figure 56 Alternator Replacement Test

Alternator Replacement Test — Amperage Output Test

1. With vehicle at shop temperature, connect carbon pile and clamp-on ammeter as shown (see Figure
above). Clamp around all wires connected to alternator “B” terminal. (To use an ammeter without an
induction clamp, disconnect circuits to alternator “B” terminal and connect meter shunt between alternator
B+ terminal and all circuits previously removed.)

CAUTION – Do not connect an ammeter without a high current shunt.

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2. With NO electrical loads turned on, start the engine, and speed up and maintain a high RPM.

3. Turn on and adjust carbon pile until ammeter reads its highest value and record ______A.

4. Turn off carbon pile and engine.

5. If reading is zero (no output), the rotor should be magnetized with the alternator hooked up normally. To do
this, momentarily connect a jumper lead from the alternator “B” terminal to the indicator “R” terminal. This
will restore normal residual magnetism.

6. Repeat steps 2, 3, and 4. If output is still zero, replace alternator.

Alternator Replacement Test — Replacement

Replace alternator if either of the following exists:

A. Output voltage exceeded 15.5V.

B. Output current is not within 10% of the alternator rated output stamped on the alternator.

4. COMPONENT LOCATIONS
B1 Battery Stud. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . ... . . . . . Power Distribution Panel
B2 Battery Stud. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . ... . . . . . Power Distribution Panel
B Alternator Stud. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . .. . . . . . Back of Alternator
G Alternator Stud. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . . ... . . . . . Back of Alternator
B Cranking Motor Solenoid Stud. . . . . . . . . . . . . . . . . . . .. . . . . . Back of Cranking Motor Solenoid
M Cranking Motor Solenoid Stud. . . . . . . . . . . . . . . . . . . .. . . . . . Back of Cranking Motor Solenoid
R Alternator Stud. . .. . . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .. . .. . . . . . Back of Alternator
S Cranking Motor Solenoid Stud. . . . . . . . . . . . . . . . . . . .. . . . . . Back of Cranking Motor Solenoid
(1) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Left Side of Engine Cowl
(2) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Right Side of Engine Cowl, Above Conn. 3
(3) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Right Side of Engine Cowl, Below Conn. 2
(40) Key Switch. .. . .. .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . ... . . . . . Behind Left Side of Instrument Panel
(275) Thermo Overload Switch. . . . . . . . . . . . . . . . . . . . . .. . . . . . At the Cranking Motor
(509) Start Feed Adapter. .. . . . . . . . . . . . . . . . .. . . . . . . . . .. . . . . . 6" Left of Fuse Panel, Near Heater Control

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Figure 57 Cab Wiring

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1. 150A MEGAFUSE
2. TO (B1) BATTERY STUD
3. START MAG SWITCH
4. NO BUS BAR WITH 3+1 BATTERY SYSTEM
5. TO HEATER
6. (3) ENGINE HARNESS CONNECTOR
7. (2) CHASSIS HARNESS CONNECTOR
8. RIGHT HAND DASH GROUND STUD
9. FUSE BLOCK GROUND STUD
10. (B2) BATTERY STUD
11. (B1) BATTERY STUD
12. KEY SWITCH
13. LEFT HAND DASH GROUND STUD
14. (1) FRONT END HARNESS CONNECTOR
15. GROUND CIRCUITS
16. DASH PANEL

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Figure 58 Cab Wiring 3+1 System

1. CIRCUIT 14A FROM START MAG SWITCH
2. 3+1 CAB HARNESS CONNECTS TO 3+1 ENGINE HARNESS
3. CIRCUIT 14A FROM 3+1 MAG SWITCH

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Figure 59 Chassis Wiring 3+1 System (Typical)

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 3 BATTERY, CHARGING AND CRANKING SYSTEMS 135

1. 3+1 BATTERY SYSTEM HARNESS

2. SEE FIGURE BELOW
3. SEE VIEW BELOW
4. CIR 14A
5. TO B2 BATTERY STUD
6. CIRCUIT 7
7. CIRCUIT 7
8. SEE VIEW ABOVE
9. 3+1 BATTERY SYSTEM HARNESS

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136 3 BATTERY, CHARGING AND CRANKING SYSTEMS

Figure 60 Chassis Wiring 3+1 System and Battery Cable Connections

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 3 BATTERY, CHARGING AND CRANKING SYSTEMS 137

1. DEEP CYCLE BATTERY

2. RED CABLE TO 7V MAGNETIC SWITCH
3. CRANKING BATTERY
4. GROUND
5. CIRCUITS 4A & 7
6. SEE FIGURE ABOVE
7. 3+1 BATTERY SYSTEM HARNESS
8. MAGNETIC SWITCH WITH 3+1 SYSTEM
9. CIRCUIT 11H, 7V MAGNETIC SWITCH
10. CRANKING BATTERY
11. CIRCUIT 11H
12. RED CABLE
13. 7V ISOLATED BATTERY MAGNETIC SWITCH
14. CIRCUIT 14FL
15. CIRCUIT 7
16. BLACK CABLE
17. CRANKING BATTERY
18. BATTERY BOX

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Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .141

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .141

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .141

4. COMPONENT LOCATIONS. .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .142

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 4 ELECTRICAL TROUBLESHOOTING ETHER START 141

1. DESCRIPTION
Use with Circuit Diagram Book CTS-5298 or S08225.

When activated, the ether start system injects a measured amount of ether into the engine intake system to
assist starting. The system will only function if the engine temperature is less than approximately 40°F (5°C).

2. OPERATION
The ether start switch on the instrument panel receives ignition voltage from 10A fuse F10-A (location may
vary) when the key is on. The switch is a momentary-on (normally open) type switch. When the switch is
closed, power is applied to the ether control valve coil. If the thermo switch is closed, a measured amount
of ether is injected into the engine intake system.

The ether control valve coil is grounded through the ether thermo switch mounted on the side of the engine
block, which closes at less than 40°F (5°C) and opens when engine block temperature exceeds 50°F (10°C).

3. TROUBLESHOOTING
1. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of charge (SOC)
or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries with an OCV of 12 volts or
less are either completely discharged or have a dead cell.

2. Before beginning these test procedures, check any light or indicator lamp filaments that are suspected of
being open (burned out). This is done to avoid unnecessary extensive circuit checks.

3. Before beginning these test procedures, inspect all connectors for loose or damaged pins, wires, etc.
Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 — ELECTRICAL in
the CTS-5000 Master Service Manual.

4. When the technician determines that a fuse is blown, while checking its condition, he is directed to locate
the cause of the overload condition and to repair it. While no further instruction on this procedure is listed in
the diagnostic tables, the common procedure is as follows: isolate sections of the circuit, by disconnecting
connectors, and measure the resistance to ground to find the circuit that is shorted to ground. Then locate
the damaged spot in the wire or connector and repair.

5. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not covered in
detail. It is assumed that the technician knows to check for a malfunctioning switch, relay, or solenoid.

Refer to circuit diagram ETHER START in CTS-5298 or S08225.

Table 29 Ether Start Table

STEP KEY ACTION TEST SPEC. YES- I N NO-OUT OF SPEC.
POINTS SPEC.
1. Off Check ether cylinder for Ether in Go to next Replace with new
ether. cylinder. step. cylinder.
2. Off Check fuse F10-A F10-A Fuse OK? Go to next Locate cause of
[location may vary]. step. overload condition,
then correct. Replace
10A fuse.

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142 4 ELECTRICAL TROUBLESHOOTING ETHER START

Table 29 Ether Start Table (cont.)

STEP KEY ACTION TEST SPEC. YES- I N NO-OUT OF SPEC.
POINTS SPEC.
3. Off Remove circuit 21A Go to next
from thermo switch and step.
jumper 21A to engine
ground.
4. On Test operation of ether Ether Replace Leave jumper in place
start system. system thermo and go to next step.
works? switch.
5. On Remove ether switch 21H to 10 to 12 Go to next Locate cause of no or
(600) and measure gnd. volts. step. low voltage in cir. 21H
voltage from circuit 21H from fuse F10-A, then
to ground. repair.
6. Off Use ohmmeter to (600), < 5 ohms. Go to next Replace switch
measure resistance terminals step. and reconnect 21,
across switch (600) 5 and 6. . 21H, and 21A. Test
terminals 5 and 6 with operation.
switch depressed.
7. Off Reconnect connector Go to next
(600) and remove step.
connector (72).
8. On At connector (72), (72), 21 10 to 12 Go to next Locate open in cir.
measure voltage to to gnd. volts. step. 21 between ether
ground at cir. 21 with switch and connector
ether switch depressed. (72), then repair. Test
operation.
9. On At connector (72), (72), 21 10 to 12 Replace Locate open in cir. 21A
measure voltage to 21A. volts. ether between ether control
between cir. 21 and control valve and thermo
21A with ether switch valve switch, then repair.
depressed. assembly. Test operation.

4. COMPONENT LOCATIONS
(1) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Left Side of Engine Cowl
(2) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Right Side of Engine Cowl, Above Connector 3
(3) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Right Side of Engine Cowl, Below Connector 2
(72) Ether Start At Dash Panel. . . . . . . . . . . . . . . . . . . . . .. . . . . . Front End Harness
(494) I1 Ignition Adapter. .. . . . .. . . . .. . . . .. . . . .. . . . .. . .. . . . . . Behind Fuse Panel
(504) L2 Panel Light Feed Adapter. .. . .. . .. . .. . .. . ... . . . . . Behind Instrument Panel/Switch Breakout
(506) L4 Panel Lights Gnd Adapter. . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel/Switch Breakout
(600) Ether Start On/Off Switch. . .. . .. . .. . .. . .. . .. . ... . . . . . At Switch Cluster

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 4 ELECTRICAL TROUBLESHOOTING ETHER START 143

Figure 61 Ether Start Cab Wiring

1. ETHER START SWITCH (600)
2. CONNECTOR (3)
3. CONNECTOR (2)
4. FUSE F10–A
5. ETHER START SWITCH (600)
6. CIRCUIT 21, PART OF MAIN CAB HARNESS
7. TO FRONT END HARNESS (1)

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144 4 ELECTRICAL TROUBLESHOOTING ETHER START

Figure 62 Ether Start Chassis and Valve Wiring

1. CIRCUITS 21 AND 21A
2. CONNECTOR (72)
3. ETHER BOTTLE
4. FRONT END HARNESS

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 4 ELECTRICAL TROUBLESHOOTING ETHER START 145

Figure 63 Ether Start Engine Wiring – Cummins ISM

1. THERMOSTAT SWITCH
2. ENGINE HARNESS
3. ENGINE HARNESS
4. CIRCUIT 21A
5. CONNECTOR (NOT LISTED)
6. THERMOSTAT SWITCH

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146 4 ELECTRICAL TROUBLESHOOTING ETHER START

Figure 64 Ether Start Engine Wiring – Cummins N-14

1. ENGINE HARNESS
2. CIRCUIT 21A
3. THERMOSTATIC SWITCH

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Figure 65 Ether Start Engine Wiring – Cummins AHD

1. CIRCUIT 21A
2. ENGINE HARNESS
3. THERMOSTATIC SWITCH

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Figure 66 Ether Start Engine Wiring – Caterpillar C-10, C-12

1. THERMOSTATIC SWITCH
2. CONNECTOR (NOT LISTED)
3. CIRCUIT 21A
4. ENGINE HARNESS

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Figure 67 Ether Start Engine Wiring – Caterpillar 3406E

1. ENGINE HARNESS
2. THERMOSTAT SWITCH
3. CONNECTOR (NOT LISTED)
4. CIRCUIT 21A

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Figure 68 Ether Start Engine Wiring – Detroit Diesel Series 60

1. ENGINE HARNESS
2. THERMOSTAT SWITCH
3. CONNECTOR (NOT LISTED)
4. ENGINE HARNESS

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Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .153
1.1. HORTON ENGINE FAN CONTROLS. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .153
1.2. KYSOR ENGINE FAN CONTROLS.. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .153

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .153
2.1. CATERPILLAR C-10, C-12 AND 3406E. . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153
ADEM III ECM Fan Control. .. . . . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . .153
Horton Engine Fan.. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .154
Kysor Engine Fan.. . .. . .. .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .155
Kysor Engine Fan.. . .. . .. .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .155
2.2. DETROIT DIESEL SERIES 60. . . . .. . . . . . . . . .. . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . .156
Horton Engine Fan Controls.. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. . . .. . .156
Kysor Engine Fan Controls. .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .157
2.3. CUMMINS N14E. . .. . . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .158
Horton Engine Fan Controls With ECM Control System. .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .158
Kysor Engine Fan Controls With ECM Control System. . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .158
2.4. CUMMINS ISM AND AHD. . . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .158
Horton Engine Fan Controls With ECM Control System. .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .158
Kysor Engine Fan Controls With ECM Control System. . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .159
2.5. INTERNATIONAL I6 HEUI.. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .159
Horton Engine Fan Controls With ECM Control System. .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .159
Kysor Engine Fan Controls With ECM Control System. . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .160

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .160
3.1. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH CATERPILLAR C–10,
C-12 AND 3406E. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .160
Testing Fan Solenoid and Circuits.. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .160
Testing A/C Compressor High Pressure Switch (228) and Circuits.. .. . .. . .. .. . .. . .. .. . .. .162
Testing (Optional) Engine Fan Override Switch (659). . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .163
3.2. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH DETROIT DIESEL
SERIES 60 DDEC III. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .164
Testing Fan Solenoid and Circuits.. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .164
Testing A/C Compressor High Pressure Switch (228) and Circuits.. .. . .. . .. .. . .. . .. .. . .. .165
3.3. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH CUMMINS M11 AND N14
CELECT. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .166
Testing Fan Solenoid and Circuits.. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .166
Testing A/C Compressor High Pressure Switch (228) and Circuits.. .. . .. . .. .. . .. . .. .. . .. .167
3.4. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH CUMMINS ISM AND
AHD. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .168
Testing Fan Solenoid and Circuits.. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .168
Testing A/C Compressor High Pressure Switch (228) and Circuits.. .. . .. . .. .. . .. . .. .. . .. .169
Testing (Optional) Engine Fan Override Switch (659). . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .169
3.5. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH INTERNATIONAL I6 HEUI
ENGINE. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .170
Testing Fan Solenoid and Circuits.. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .171
Testing A/C Compressor High Pressure Switch (228) and Circuits.. .. . .. . .. .. . .. . .. .. . .. .171

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4. COMPONENT LOCATIONS. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . ..172

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1. DESCRIPTION
1.1. HORTON ENGINE FAN CONTROLS
The ECM is used to control the Horton engine cooling fan. Other fan control components include:

• Horton fan clutch assembly.

• A Normally Open (N.O.) Fan Solenoid (227).
• A Normally Closed (N.C.) Air Conditioning (A/C) High Pressure Switch (228).
• An optional engine fan override switch (659).

The fan solenoid relay is controlled by the ECM using information from the coolant temperature sensor,
retarder solenoid status and A/C high pressure switch.

The optional engine fan override switch allows the driver to disable the control voltage from the ECM and keep
the fan turned on. An indicator will light during the time the fan would normally be off.

1.2. KYSOR ENGINE FAN CONTROLS

The ECM is used to control the Kysor engine cooling fan. Other fan control components include:

• A Kysor Fan clutch assembly.

• A Normally Open (N.C.) Fan Solenoid (227).
• A Normally Closed (N.C.) Air Conditioning (A/C) High Pressure Switch (228).
• An optional engine fan override switch (659).

The solenoid relay is controlled by the ECM using information from the coolant temperature sensor, retarder
solenoid status and A/C high pressure switch.

The optional engine fan override switch allows the driver to disable the control voltage from the ECM and
keep the fan turned on.

2. OPERATION
2.1. CATERPILLAR C-10, C-12 AND 3406E
ADEM III ECM Fan Control

Refer to circuit diagram HORTON AND KYSOR ENGINE FAN WITH C10, C12, and 3406E ENGINES circuits
in CTS-5298 or S08225.

The ECM uses inputs from the engine coolant temperature sensor, retarder solenoid status and the A/C high
pressure switch (228) to determine when the fan should be on. To turn the fan on, the ECM applies OV to the
fan solenoid relay. To turn the fan off, the ECM applies 12V to the fan solenoid relay.

The ECM turns the fan on under the following conditions:

• If the engine speed is less than 2250 RPM and any of the following conditions exists:
• Engine not running or

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154 5 ELECTRICAL TROUBLESHOOTING FANS

• During engine cranking or

• Coolant temperature sensor is greater than 205°F (96°C) for C-10 and C-12 or
• Coolant temperature sensor is greater than 216°F (102°C) for 3406E or
• Intake manifold air temperature is greater than 180°F (82°C) or
• Intake manifold air temperature is greater than 151°F (66°C) with boost pressure greater than 10 psi
(70kPa).

There is an active diagnostic code for the coolant temperature sensor or

• The retarder solenoid signal is active (high mode) for more than 2 seconds (dependent upon customer
programming) or
• A/C high pressure switch open or EC is counting (dependent upon customer programming) or

The ECM turns the fan off under the following conditions:

• Engine speed is greater than 2250 RPM or all of the following conditions exists:
• Coolant temperature sensor is less than 198°F (92°C) for C-10 and C-12 or Coolant temperature sensor is
less than 207°F (97°C) for 3406E and
• The fan has been on for 30 seconds and
• Engine retarder ON strategy is not active and
• A/C high pressure switch is not active.

NOTE – Once the ECM has turned the fan on, the fan will remain on for a minimum of 30 seconds to
avoid unnecessary fan clutch cycling (except at engine start-up: it will run for only two seconds after
the engine has reached the programmed low idle (700–750 rpm).

When the ECM energizes the fan solenoid, it causes the fan solenoid to energize. This disengages the
fan clutch.

Horton Engine Fan

Horton Fan Clutch Assembly - The fan clutch is engaged by air pressure supplied by the fan solenoid. The
fan clutch is spring loaded off and air pressure is required to overcome the spring and engage the clutch.

Horton Normally Open Fan Solenoid (227) -The N.O. fan solenoid (227) supplies air pressure to engage the
fan clutch when the solenoid is not energized. Energizing the solenoid turns off the air pressure to the fan
clutch, causing the fan clutch to disengage.

When the optional engine fan override switch is not installed, the solenoid is energized by a 12V signal
on circuit 23A from ECM connector (400) terminal 28. The solenoid ground circuit, 23–GA, is grounded
through circuit 11–GC.

When the optional engine fan override switch is installed, the solenoid is energized by a 12V signal on circuit
23A from ECM connector (400) terminal 28 through switch (659). The solenoid ground circuit, 23–GA, is
grounded through circuit 11–GC.

The engine fan override switch has an indicator LED which will light during the time the fan would normally be
off, when the override switch is on. The 12V signal on circuit 23A from ECM connector (400) terminal 28 will
flow through the LED in switch (659). The LED is grounded through circuit 23–GY.

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The engine fan override switch is illuminated with an LED. 12 volts from the panel feed adapter (503) is
supplied on circuit 62M. Ground for the LED is supplied on circuit 11–GR.

Kysor Engine Fan

When the optional engine fan override switch is installed, the solenoid is energized by a 12V signal on circuit
23A from ECM connector (400) terminal 28 through switch (659). The solenoid ground circuit, 23–GA, is
grounded through circuit 11–GC.

Kysor Fan/Clutch Assembly —The fan clutch is disengaged by air pressure supplied by the fan solenoid. The
fan clutch is spring loaded on and air pressure is required to overcome the spring and disengage the fan clutch.

Kysor Normally closed (N.C.) Fan Solenoid (227) — The N.C. fan solenoid (227) does not supply air
pressure to disengage the fan clutch when the solenoid is not energized. Energizing the solenoid turns on
the air pressure to the fan clutch, causing the fan clutch to disengage.

When the optional engine fan override switch is not installed, the solenoid is energized by a 12V signal
on circuit 23A from ECM connector (400) terminal 28. The solenoid ground circuit, 23–GA, is grounded
through circuit 11–GC.

The engine fan override switch has an indicator lamp which will light during the time the fan would normally be
off, when the override switch is on. The 12V signal on circuit 23A from ECM connector (400) terminal 28 will
flow through the LED in switch (659). The LED is grounded through circuit 23–GY.

The engine fan override switch is illuminated with an LED. 12 volts from the panel feed adapter (503) is
supplied on circuit 62M. Ground for the LED is supplied on circuit 11–GR.

Kysor Engine Fan

When the optional engine fan override switch is installed, the solenoid is energized by a 12V signal on circuit
23A from ECM connector (400) terminal 28 through switch (659). The solenoid ground circuit, 23–GA, is
grounded through circuit 11–GC.

Kysor Fan/Clutch Assembly — The fan clutch is disengaged by air pressure supplied by the fan solenoid. The
fan clutch is spring loaded on and air pressure is required to overcome the spring and disengage the fan clutch.

Kysor Normally Closed (N.C.) Fan Solenoid (227) —The N.C. fan solenoid (227) does not supply air
pressure to disengage the fan clutch when the solenoid is not energized. Energizing the solenoid turns on
the air pressure to the fan clutch, causing the fan clutch to disengage.

When the optional engine fan override switch is not installed, the solenoid is energized by a 12V signal
on circuit 23A from ECM connector (400) terminal 28. The solenoid ground circuit, 23–GA, is grounded
through circuit 11–GC.

The engine fan override switch has an indicator lamp which will light during the time the fan would normally be
off, when the override switch is on. The 23V signal on circuit 23A from ECM connector (400) terminal 28 will
flow through the LED in switch (659). The LED is grounded through circuit 23–GY.

The engine fan override switch is illuminated with an LED. 12 volts from the panel feed adapter (503) is
supplied on circuit 62M. Ground for the LED is supplied on circuit 11–GR.

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2.2. DETROIT DIESEL SERIES 60

Horton Engine Fan Controls

Refer to circuit diagram HORTON AND KYSOR ENGINE FAN WITH SERIES 60 ENGINE circuits in CTS-5298
or S08225.

The ECM controls the Horton fan system. The Horton fan clutch is spring-loaded so the fan is off. Air pressure
from a normally open (N.O.) fan solenoid is used to engage the fan clutch.

The ECM controls the fan solenoid (227) by opening or closing the solenoid ground. The ECM turns the fan on
when at least one of the following conditions occur:

• Oil temperature above DDEC III factory set limits.

• Coolant temperature above DDEC III factory set limits.
• Air temperature above DDEC III factory set limits.
• Air conditioning (A/C) compressor high pressure switch is open. The fan will remain on a minimum of 3
minutes after the switch closes.
• Oil temperature sensor fails.
• Coolant temperature sensor fails.
• Air temperature sensor fails.
• Pressure governor switch is active.
• Engine brake is on in 6 cylinder position. Fan will remain on a minimum of 30 seconds.

Horton Fan Solenoid (227) — The normally open (N.O.) fan solenoid supplies air pressure to engage the fan
clutch. When the solenoid is not energized, the fan clutch is engaged. The solenoid receives ignition
power from 10A fuse F9–A, whenever the key is on. The solenoid coil ground is connected by circuit 23D to
ECM connector (273) terminal A2. A2 is an ECM digital output terminal. ECM connector (273) terminal A2
is either low (ground) or high (12 volts).

When the ECM wants the fan off, terminal A2 and circuit 23D are low (ground). This grounds the fan solenoid
causing it to energize and air pressure necessary to engage the fan is turned off.

When the ECM wants the fan on, ECM connector (273) terminal A2 and circuit 23D are high (12 volts),
causing the fan solenoid (227) to be de-energized (no ground). with the solenoid de-energized, air pressure
from the normally open solenoid engages the fan clutch.

AC High Pressure Switch (228) — This switch is normally closed and opens when A/C compressor head
pressure exceeds 300 psi. The switch closes when the head pressure drops below 210 psi.

Digital input circuit 23C from ECM connector (273) terminal F1 is connected to one side of the A/C pressure
switch. The other switch terminal is connected by circuit 23–GB to ground. With the switch in its normally
closed position, circuit 23C is low (ground). When the switch is open, circuit 23C is high (5V).

When the ECM sees circuit 23C high, it causes fan solenoid circuit 23D to be at a HIGH state (12V), which
de-energizes the fan solenoid, engaging the fan clutch. When this occurs, the fan clutch will remain engaged
for a minimum of three minutes after the A/C pressure switch returns to a closed position, to reduce fan cycling.

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Kysor Engine Fan Controls

The ECM controls the Kysor fan system. The Kysor fan clutch is spring-loaded so the fan is on. Air pressure
from a normally closed (N.C.) fan solenoid is used to disengage the fan clutch.

The ECM controls the fan solenoid (227) by opening or closing the solenoid ground. The ECM turns the fan on
when at least one of the following conditions occur:

• Oil temperature above DDEC III factory set limits.

• Coolant temperature above DDEC III factory set limits.
• Air temperature above DDEC III factory set limits.
• Air conditioning (A/C) compressor high pressure switch is open (International installed switch and circuits).
The fan will remain on a minimum of 3 minutes after the switch closes.
• Oil temperature sensor fails.
• Coolant temperature sensor fails.
• Air temperature sensor fails.
• Pressure governor switch is active.
• Engine brake is on in 6 cylinder position. Fan will remain on a minimum of 30 seconds.

The International– installed components include the fan clutch, fan solenoid (227), and the A/C high pressure
switch (228).

Kysor Fan Solenoid (227) —The normally closed (N.C.) fan solenoid supplies air pressure to disengage
the fan clutch. When the solenoid is not energized, the fan clutch is engaged. The solenoid receives
power from 10A fuse F9–A, whenever the key is on. The solenoid coil ground is connected by circuit 23D to
ECM connector (273 terminal A2. A2 is an ECM digital output terminal. ECM connector (273) terminal A2
is either low (ground) or high (12 volts).

When the ECM wants the fan off, terminal A2 and circuit 23D are low (ground). This grounds the fan solenoid
causing it to energize and to provide the air pressure necessary to disengage the fan.

When the ECM wants the fan on, ECM connector (273) terminal A2 and circuit 23D are high (12 volts),
causing the fan solenoid (227) to be de-energized (no ground). With the solenoid de-energized, there is no air
pressure from the normally closed solenoid applied to the fan clutch, which is spring loaded on.

AC High Pressure Switch (228) — This switch is normally closed and opens when A/C compressor head
pressure exceeds 300 psi. The switch closes when the head pressure drops below 210 psi.

Digital input circuit 23C from ECM connector (273) terminal F1 is connected to one side of the A/C pressure
switch. The other switch terminal is connected by circuit 23–GB to ground. With the switch in its normally
closed position, circuit 23C is low (ground). When the switch is open, circuit 23C is high (5V).

When the ECM sees circuit 23C high, it causes fan solenoid circuit 23D to be at a HIGH state (12V), which
de-energizes the fan solenoid, engaging the fan clutch. When this occurs, the fan clutch will remain engaged
for a minimum of three minutes after the A/C pressure switch returns to a closed position, to reduce fan cycling.

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2.3. CUMMINS N14E

Horton Engine Fan Controls With ECM Control System

Refer to circuit diagram HORTON AND KYSOR ENGINE FAN WITH N14E ENGINES circuits in CTS-5298
or S08225.

To turn the fan off: The ECM applies 12 volts through the 21–way ECM Interface connector (251) to circuit
23D to the fan solenoid (227), causing the solenoid to energize, turning off the air pressure which keeps the
fan engaged. The fan is spring loaded in the disengaged position.

Turning the fan on: The fan is turned on two ways:

A. When the ECM senses the engine coolant has reached the preset temperature limit, the ECM
turns off the voltage to circuit 23D. This causes the fan solenoid to de-energize, which applies air
pressure to the fan clutch engaging the fan.
B. The second way the fan is turned on is when the A/C compressor head pressure exceeds 300
psi, the A/C high pressure switch (228) opens and removes the ground on circuit 23C to ECM
connector terminal T. The ECM will turn off 12 volts on circuit 23D. This causes the fan solenoid to
de-energize, which applies air pressure to the fan clutch engaging the fan. When the A/C head
pressure drops below 210 psi, the switch closes, the ECM applies 12 volts to circuit 23D which
energizes the fan solenoid and the fan turns off.
Kysor Engine Fan Controls With ECM Control System

To turn the fan off: The ECM applies 12 volts through the 21–way ECM interface connector (251) to circuit
23D to the fan solenoid (227), causing the solenoid to energize, turning on the air pressure which overrides
the fan clutch spring, turning the fan off.

Turning the fan on: The fan is turned on two ways:

A. When the ECM senses the engine coolant has reached the preset temperature limit, the ECM
turns off the voltage to circuit 23D. This causes the fan solenoid to de-energize, which applies air
pressure to the fan clutch engaging the fan.
B. The second way the fan is turned on is when the A/C compressor head pressure exceeds 300
psi, the A/C high pressure switch (228) opens and removes the ground on circuit 23C to ECM
connector terminal T. The ECM will turn off 12 volts on circuit 23D. This causes the fan solenoid to
de-energize, which applies air pressure to the fan clutch engaging the fan. When the A/C head
pressure drops below 210 psi, the switch closes, the ECM applies 12 volts to circuit 23D which
energizes the fan solenoid and the fan turns off.

2.4. CUMMINS ISM AND AHD

Horton Engine Fan Controls With ECM Control System

Refer to circuit diagram HORTON AND KYSOR ENGINE FAN WITH AHD and ISM ENGINES circuits in
CTS-5298 or S08225.

To turn the fan off: When the optional engine fan override switch is not installed, the ECM applies 12 volts on
circuit 23A from ECM connector (1093) terminal 28 circuit 23D to the fan solenoid (227), causing the solenoid
to energize, turning off the air pressure that keeps the fan engaged. The fan is spring loaded in the disengaged
position. The solenoid is grounded through circuit 23–GA and 11–GC.

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When the optional engine fan override switch is installed, the solenoid is energized by 12 volts on circuit
23A from ECM connector (1093) terminal 28 through switch (659), which then applies the voltage on circuit
23D to the fan solenoid (227), causing the solenoid to energize, turning off the air pressure that keeps the
fan engaged. The fan is spring loaded in the disengaged position. The solenoid is grounded through circuit
23–GA and 11–GC.

The engine fan override switch has an indicator lamp which will light, during the time the fan would normally be
off, when the override switch is on. The 12V signal on circuit 23A from ECM connector (400) terminal 28 will
flow through the LED in switch (659). The LED is grounded through circuit 23–GY.

The engine fan override switch is illuminated with an LED. 12 volts from the panel feed adapter (503) is
supplied on circuit 62M. Ground for the LED is supplied on circuit 11–GR.

Turning the fan on: The fan is turned on two ways:

A. When the ECM senses the engine coolant has reached the preset temperature limit, the ECM
turns off the voltage to circuit 23D. This causes the fan solenoid to de-energize, which applies air
pressure to the fan clutch engaging the fan.
B. The second way the fan is turned on is when the A/C compressor head pressure exceeds 300 psi,
the A/C high pressure switch (228) opens the fan solenoid circuit. This causes the fan solenoid to
de-energize, which applies air pressure to the fan clutch engaging the fan. When the A/C head
pressure drops below 210 psi, the switch closes, energizing the fan solenoid and the fan turns off.

Kysor Engine Fan Controls With ECM Control System

To turn the fan off: The ECM applies 12 volts through the 21–way ECM interface connector (251) to circuit
23A, which is connected to the normally closed A/C high pressure switch (228), which then applies the voltage
on circuit 23D to the fan solenoid (227), causing the solenoid to energize, turning on the air pressure which
overrides the fan clutch spring, turning the fan off.

When the optional engine fan override switch is not installed, the solenoid is energized by a 12V signal
on circuit 23A from ECM connector (400) terminal 28. The solenoid ground circuit, 23–GA, is grounded
through circuit 11–GC.

When the optional engine fan override switch is installed, the solenoid is energized by a 12V signal on circuit
23A from ECM connector (400) terminal 28 through switch (659). The solenoid ground circuit 23–GA, is
grounded through circuit 11–GC.

The engine fan override switch has an indicator lamp which will light when the override switch is on. The 12V
signal on circuit 23A from ECM connector (400) terminal 28 will flow through the LED in switch (659). The
LED is grounded through circuit 23–GY.

The engine fan override switch is illuminated with an LED. 12 volts from the panel feed adapter (503) is
supplied on circuit 62M. Ground for the LED is supplied on circuit 11–GR.

2.5. INTERNATIONAL I6 HEUI

Horton Engine Fan Controls With ECM Control System

Refer to circuit diagram HORTON AND KYSOR ENGINE FAN WITH I6 HUEI ENGINES circuits in CTS-5298
or S08225.

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To turn the fan off: The ECM applies a ground through the gray engine connector, pin 8, to fan control
connector (1075) terminal A. Circuit 97EFS, from engine fan control connector (1075) terminal A, connects
to the fan solenoid (227), causing the solenoid to energize, turning off the air pressure that keeps the fan
engaged. The fan is spring loaded in the disengaged position. 12 volts is supplied to fan solenoid connector
(227), terminal A from key switch (40) through circuit 13, circuit 13U, fuse F9–A, circuit 23 and circuit 23D.

Turning the fan on: The fan is turned on two ways:

A. When the ECM senses the engine coolant has reached the preset temperature limit, the ECM
removes the ground from circuit 97EFS. This causes the fan solenoid to de-energize, which
applies air pressure to the fan clutch engaging the fan.
B. The second way the fan is turned on is when the A/C compressor head pressure exceeds a preset
limit the A/C high pressure switch (228) opens and signals the EC to engage the fan. When the A/C
head pressure drops below a preset limit the switch closes, signaling the ECM to turn the fan off.

Kysor Engine Fan Controls With ECM Control System

To turn the fan off: The ECM applies a ground on circuit 97EFS from engine fan control connector (1075)
terminal A to the fan solenoid (227), causing the solenoid to energize, turning on the air pressure which
overrides the fan clutch spring, turning the fan off. 12 volts is supplied to fan solenoid connector (227), terminal
A from key switch (40) through circuit 13, circuit 13U, fuse F9–A, circuit 23 and circuit 23D.

Turning the fan on: The fan is turned on similarly to the Horton fan except air pressure is removed when the
solenoid is de-energized. This permits the fan clutch spring to engage the fan.

3. TROUBLESHOOTING
A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 —
ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit, by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not
covered in detail. It is assumed that the technician knows to check for a malfunctioning switch,
relay, or solenoid.

3.1. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH CATERPILLAR
C–10, C-12 AND 3406E
Testing Fan Solenoid and Circuits

Refer to HORTON and KYSOR ENGINE FAN WITH C10, C12 AND 3406E ENGINES circuit diagram in
CTS-5298 or S08225.

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Before beginning this test procedure, inspect all connectors for loose or damaged pins, wires, etc.

International OEM connector (400) mates with Caterpillar ECM OEM connector. This is an AMP 40–pin
connector, with the International side having female terminals (sockets) and the Caterpillar side having pins.

NOTE – No tests in this manual require testing “into” the Caterpillar OEM connector.

When testing the International side of connector (400), never insert meter probes into the sockets, as
the probes will damage the sockets. Always use test leads of the type described in Inspecting Electrical
Connectors, Test Leads of this manual. The test leads must fit snugly into the sockets without expanding
the sockets.

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

Table 30 Testing Fan Solenoid and Circuits

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connector (227), <5 ohms. Go to next Locate open or poor
(227) from the terminal B step. connection in circuit
solenoid pigtail. to gnd. 23-GA or 11-GC
Measure resistance between connector
from (227) terminal B (227) and ground,
to ground. then repair.
2. Off Disconnect connector (400), <5 ohms. Go to next Locate open or poor
(400). Insure the terminal step. connection in circuit
optional "engine fan 11 to (227) 23A and 23B or "fan
override switch" (659) terminal A. override switch" (659)
is in the off position. between connector
Measure resistance (227) and (400), then
from (400) terminal 11 repair.
to (227) terminal A.
3. Off Measure resistance (400), >100K Go to next Locate short to ground
from (400) terminal 11 terminal 11 ohms step. in circuit 23A or 23B,
to ground. to gnd. then repair.
4. On Reconnect (227) Sole- noid Go to next Replace fan solenoid.
to solenoid. Install ener- step.
a jumper from (400) gizes
terminal 28 to 12 volts.
Does the solenoid
energize?

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Table 30 Testing Fan Solenoid and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF SPEC.
POINTS SPEC.
5. Off Disconnect connector (400), <5 ohms Go to next Locate open or poor
(400). Insure the terminal step. connection in circuit
optional engine fan 11 to (227) 23A and 23B between
override switch is terminal A. connector (227) and
in the off position. (400), then repair.
Measure resistance
from (400) terminal 11
to (227) terminal A.
6. Off Reconnect
connectors. The fan
control circuits and
components check
good.

Testing A/C Compressor High Pressure Switch (228) and Circuits

Refer to HORTON & KYSOR ENGINE FAN WITH C–10, C–12 and 3406E ENGINES circuit diagram in
CTS-5298 or S08225.

Before beginning this test procedure, inspect all connectors for loose or damaged pins, wires, etc.

NOTE – Perform the preceding test, Testing Fan Solenoid and Circuits, before performing this test.

Table 31 Testing A/C Compressor High Pressure Switch (228) and Circuits
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Disconnect connectors A/C pressure <5 ohms. Go to next Replace switch.
(228) and (400). At switch. step.
A/C pressure switch,
measure resistance
across the switch
terminals. (If you
suspect the switch is
not opening at 300 PSI,
replace switch.)
2. Off Measure resistance (400) <5 ohms. Go to next Locate open in
from (400) terminal 5, terminal 5 step. circuit 23-G or
circuit 97-G, to (228) to (228) 97-G between
terminal B, circuit 23-G. terminal B. (400) and (228),
then repair.
3. Off Measure resistance (400) >5 ohms. Go to next Locate open
from (400) terminal 41 terminal 41 step. in circuit 23C
to (228) terminal A, to (228) between (400)
circuit 23C. terminal A. and (228), then
repair.

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Table 31 Testing A/C Compressor High Pressure Switch (228) and Circuits (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
4. Off Measure resistance (400), >100K Go to next Locate short to
from (400) terminal 41 terminal 41 ohms. step. ground in circuit
to ground. to ground. 23C, then repair.
5. Off The A/C high pressure
switch circuits check
good. Reconnect
(400) and (228). If you
suspect the A/C switch
is not working properly,
replace the switch and
test system operation.

Testing (Optional) Engine Fan Override Switch (659)

Refer to HORTON & KYSOR ENGINE FAN WITH C-10, C-12 and 3406E ENGINES circuit diagram in
CTS-5298 or S08225.

This switch is intended to last the life of the truck. If it is determined to be defective it should be replaced. It
is not a repairable item.

Table 32 Testing (Optional) Engine Fan Override Switch (659)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Disconnect connectors Engine Fan <5 ohms. Go to Replace switch.
(659). With the switch Override next
in the "Off" position, Switch (659), step.
measure the resistance terminals 4
between terminals 4 and and 5.
5.
2. Off With the switch in the Engine Fan <5 ohms. Go to Replace switch.
"On" position, measure Override next
the resistance between Switch (659), step.
terminals 5 and 6. terminals 5
and 6.
3. Off Connect 12 volts to LED Go to Replace switch.
terminal 7 and ground illuminates. next
to terminal 8. Does the step.
LED illuminate?
4. Off Connect 12 volts to LED Go to Replace switch.
terminal 7 and ground illuminates. next
to terminal 8. Does the step.
LED illuminate?

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Table 32 Testing (Optional) Engine Fan Override Switch (659) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
5. Off Connect 12 volts to LED Go to Replace switch.
terminal 6 and ground illuminates. next
to terminal 1. Does the step.
LED illuminate?
6. Off Switch tests good. Switch Identify problems
Reconnect switch. operates with circuit 62M
correctly. to panel feed
adapter or circuits
11-GR or 23-GY
to ground.

3.2. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH DETROIT
DIESEL SERIES 60 DDEC III
Testing Fan Solenoid and Circuits

Refer to HORTON & KYSOR ENGINE FAN WITH SERIES 60 ENGINES circuit diagram in CTS-5298
or S08225.

Before beginning this test procedure, inspect all connectors for loose or damaged pins, wires, etc.

Table 33 Testing Fan Solenoid and Circuits

STEP KEY ACTION TEST SPEC. YES-IN SPEC. NO-OUT OF
POINTS SPEC.
1. Off Check 10A fuse F9-A F9-A <1 ohm. Go to next step. Locate cause of
for open condition. overload condition,
Fuse OK? then repair.
Replace fuse.
NOTE: A blown
fuse will cause
fan to be engaged
all the time.
2. Off/ On Disconnect fan (227), 23 12 ± 1.5 Go to next step. Locate cause of no
solenoid at connector to gnd. volts. or low voltage in
(227). Turn key on and circuit 23 from fuse,
measure voltage to then repair.
ground at circuit 23 of
connector (227).
3. Off At solenoid side of Go to next step. Replace the fan
connector (227) jumper solenoid.
black wire to gnd.
and apply 12V to red
wire. Does solenoid
energize?

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Table 33 Testing Fan Solenoid and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN SPEC. NO-OUT OF
POINTS SPEC.
4. Off With (227) still (273), >100K Go to next step. Locate short to
disconnected, remove A2 to ohms. ground in circuit
connector (273) from gnd. 23D, between
ECM. At connector connectors (273)
(273) terminal A2 and (227), then
measure resistance to repair.
ground.
5. On With (227) still (273), <1 volt. Go to next step. Locate short in
disconnected, at A2 to circuit 23D to
connector (273) gnd. unwanted voltage
terminal A2 measure source, then repair.
voltage to ground.
6. Off/ On Connect (227) to fan Fan solenoid Locate open or
solenoid At connector and circuit check poor connection in
(273) use test lead good. Go to circuit 23D between
to jumper terminal following test, connectors (273)
A2 to gnd. Turn key Testing A/C and (227), then
on. Does solenoid Compressor repair.
energize? High Switch
Pressure Switch
(228) and
Circuits.

Testing A/C Compressor High Pressure Switch (228) and Circuits

Refer to HORTON and KYSOR ENGINE FAN WITH SERIES 60 ENGINES circuit diagram in CTS-5298
or S08225.

Before beginning this test procedure, inspect all connectors for loose or damaged pins, wires, etc.

NOTE – Perform preceding test, Testing Solenoid and Circuits, before performing this test.

Table 34 Testing A/C Compressor High Pressure Switch (228) and Circuits
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (273) (273), F1 >100K Go to next Locate short to ground
from ECM. Disconnect to gnd. ohms. step. in circuit 23C between
connector (228) from connectors (273) and
A/C pressure switch. At (228), then repair.
connector (273) terminal
F1, measure resistance
to gnd.
2. Off With A/C pressure switch A/C <5 ohms. Go to next Replace switch.
disconnected, measure pressure step.
resistance between switch.
switch terminals.

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Table 34 Testing A/C Compressor High Pressure Switch (228) and Circuits (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
3. Off At connector (228) (228), <5 ohms. Go to next Locate open or poor
measure resistance to 23-GB to step. connection in circuit
ground at circuit 23-GB. gnd. 23-GB or path to
ground at neg. battery
terminal, then repair.
4. Off Connect (228) to switch. (273), F1 <5 ohms. Go to next Locate open or
At connector (273) to gnd. step. poor connection in
terminal F1, measure circuit 23C between
resistance to ground. connectors (273) and
(228), then repair.
5. Off A/C high pressure switch
and circuits check good.
If you suspect that the
A/C high pressure switch
is not opening at the
correct pressure, replace
the switch and retest.

3.3. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH CUMMINS
M11 AND N14 CELECT
Testing Fan Solenoid and Circuits

Refer to HORTON and KYSOR ENGINE FAN WITH N14 ENGINE circuit diagram in CTS-5298 or S08225.

Before beginning this test procedure, inspect all connectors for loose or damaged pins, wires etc.

Table 35 Testing Fan Solenoid and Circuits

STEP KEY ACTION TEST SPEC. YES NO-OUT OF SPEC.
POINTS - IN
SPEC.
1. Off Disconnect connector (227), <5 ohms. Go to Locate open or poor
(227) from the solenoid terminal next connection in circuit
pigtail. Measure B to gnd. step. 23-GA or 11-GU
resistance from (227) between connector
terminal B to ground. (227) and ground,
then repair.
2. Off Disconnect connector (251), <5 ohms. Go to Locate open or
(251). Measure terminal next poor connection in
resistance from (251) C to (227) step. circuit 23A between
terminal C to (227) terminal connector (227) and
terminal A. A. (251), then repair.
3. Off Measure resistance (251), >100K ohms. Go to Locate short to
from (251) terminal C to terminal next ground in circuit
ground. C to gnd. step. 23D, then repair.

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Table 35 Testing Fan Solenoid and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES NO-OUT OF SPEC.
POINTS - IN
SPEC.
4. On Reconnect (227) to Solenoid Go to Replace fan
solenoid. Install a energizes. next solenoid.
jumper from (251) step.
terminal C to 12 volts.
Does the solenoid
energize?
5. Off Reconnect connectors.
The fan control circuits
and components check
good.

Testing A/C Compressor High Pressure Switch (228) and Circuits

Refer to HORTON and KYSOR ENGINE FAN WITH N14 ENGINE circuit diagram in CTS-5298 or S08225.

Before beginning this test procedure, inspect all connectors for loose or damaged pins, wires etc.

NOTE – Perform preceding test, Testing Fan Solenoid and Circuits, before performing this test.

Table 36 Testing A/C Compressor High Pressure Switch (228) and Circuits
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connectors A/C pressure <5 ohms. Go to Replace switch.
(251), (252) and (190). switch. next
At A/C pressure switch, step.
measure resistance
across the switch
terminals. (If you
suspect the switch is
not opening at 300 PSI,
replace switch.)
2. Off Measure resistance (251), <5 ohms. Go to Locate open in
from (251) terminal T to terminal T to next circuit 23C between
(228) terminal A. (228) terminal step. (251) and (228),
A. then repair.
3. Off Measure resistance (251), >100K Go to Locate short to
from (251) terminal T to terminal T to ohms. next ground in circuits
ground. gnd. step. 23C, then repair.
4. Off Measure resistance (252) terminal <5 ohms. Go to Locate open in
from (252) terminal 10 10 to (228) next circuit 23-GB or
to (228) terminal B. terminal B. step. 97-G between (252)
and (228), then
repair.

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Table 36 Testing A/C Compressor High Pressure Switch (228) and Circuits (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
5. Off Measure resistance (190) terminal <5 ohms. Go to Locate open in
from (190) terminal V to V to (228) next circuit 23-GB or
(228) terminal B. terminal B. step. 97-GA between
(252) and (190).
Repair condition.
6. Off Reconnect connectors.
The A/C pressure switch
circuits and components
check good.

3.4. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH CUMMINS
ISM AND AHD
Testing Fan Solenoid and Circuits

Refer to HORTON and KYSOR ENGINE WITH AHD and ISM ENGINE circuit diagram in CTS-5298 or S08225.

Before beginning this test procedure, inspect all connectors for loose or damaged pins, wires, etc.

Table 37 Testing Fan Solenoid and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connector (227), <5 ohms. Go to Locate open or poor
(227) from the solenoid terminal next connection in circuit
pigtail. Measure B to gnd. step. 23-GA or 11-GU
resistance from (227) between connector
terminal B to ground. (227) and ground,
then repair.
2. Off Disconnect connector (251), <5 ohms. Go to Locate open or
(251). Measure term. C next poor connection in
resistance from (251) to (2274) step. circuit 23A between
terminal C to (227) term. A. connector (227) and
terminal A. (251), then repair.
3. Off Measure resistance (251), >100K Go to Locate short to
from (251) terminal C to terminal ohms. next ground in circuit
ground. C to gnd. step. 23D, then repair.
4. On Reconnect (227) to Solenoid Go to Replace fan solenoid.
solenoid. Install a jumper energizes. next
from (251) terminal C step.
to 12 volts. Does the
solenoid energize?
5. Off Reconnect connectors.
The fan control circuits
and components check
good.

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 5 ELECTRICAL TROUBLESHOOTING FANS 169

Testing A/C Compressor High Pressure Switch (228) and Circuits

Refer to HORTON and KYSOR ENGINE WITH AHD and ISM ENGINE circuit diagram in CTS-5298 or S08225.

Before beginning this test procedure, inspect all connectors for loose or damaged pins, wires, etc.

NOTE – Perform preceding test, Testing Fan Solenoid and Circuits, before performing this test.

Table 38 Testing A/C Compressor High Pressure Switch (228) and Circuits
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connectors A/C <5 ohms. Go to Replace switch.
(251), (252) and (190). pressure next
At A/C pressure switch, switch. step.
measure resistance
across the switch
terminals. (If you suspect
the switch is not opening
at 300 PSI, replace
switch.)
2. Off Measure resistance from (251) <5 ohms. Go to Locate open in circuit
(251) terminal T to (228) terminal T next 23C between (251) and
terminal A. to (228) step. (228), then repair.
terminal A.
3. Off Measure resistance (251), >100K Go to Locate short to ground
from (251) terminal T to terminal T ohms. next in circuits 23C, then
ground. to gnd. step. repair.
4. Off Measure resistance from (252) <5 ohms. Go to Locate open in circuit
(252) terminal 10 to (228) terminal next 23-GB or 97-G between
terminal B. 10 to (228) step. (252) and (228), then
terminal B. repair.
5. Off Measure resistance from (190) <5 ohms. Go to Locate open in circuit
(190) terminal V to (228) terminal V next 23-GB or 97-GA
terminal B. to (228) step. between (252) and
terminal B. (190). Repair condition.
6. Off Reconnct connectors.
The A/C pressure switch
circuits and components
check good.

Testing (Optional) Engine Fan Override Switch (659)

Refer to HORTON and KYSOR ENGINE FAN WITH AHD and ISM ENGINE circuit diagram in CTS-5298
or S08225.

This switch is intended to last the life of the truck. If it is determined to be defective it should be replaced. It
is not a repairable item.

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Table 39 Testing (Optional) Engine Fan Override Switch (659)

STEP KEY ACTION TEST POINTS SPEC. YES-IN NO-OUT OF SPEC.
SPEC.
1. Off Disconnect connectors Engine Fan <5 ohms. Go to Replace switch.
(659). With the switch Override next
in the "Off" position, Switch (659), step.
measure the resistance terminals 4 and
between terminals 4 and 5.
5.
2. Off With the switch in the Engine Fan <5 ohms. Go to Replace switch.
"On" position, measure Override next
the resistance between Switch (659), step.
terminals 5 and 6. terminals 5 and
6.
3. Off Connect 12 volts to LED Go to Replace switch.
terminal 7 and ground illuminates. next
to terminal 8. Does the step.
LED illuminate?
4. Off Connect 12 volts to LED Go to Replace switch.
terminal 7 and ground illuminates. next
to terminal 8. Does the step.
LED illuminate?
5. Off Connect 12 volts to LED Go to Replace switch.
terminal 6 and ground illuminates. next
to terminal 1. Does the step.
LED illuminate?
6. Off Switch tests good. Switch Identify problems
Reconnect switch. operates with circuit 62M to
correctly. panel feed adapter
or circuits 11-GR or
23-GY to ground.

3.5. ENGINE COOLING FAN CONTROLS, HORTON AND KYSOR WITH

INTERNATIONAL I6 HEUI ENGINE
Refer to HORTON and KYSOR ENGINE FAN WITH I6 HEUI ENGINE circuit diagrams in CTS-5298 or S08225.

Before beginning these test procedures, inspect all connectors for loose or damaged pins, wires, etc.

CEC module connector (379) mates with the ECM connector. This is a 60–pin connector, with the chassis
side having female terminals (sockets) and the engine side having pins.

NOTE – No tests in this manual require testing “into” the black ECM connector.

When testing the chassis side of connector (379), never insert meter probes into the sockets, as the
probes will damage the sockets. Always use breakout box (ZTSE-4445) as described in International
Engine/Vehicle Manual EGES-175.

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Testing Fan Solenoid and Circuits

Table 40 Testing Fan Solenoid and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connector (227), <5 ohms. Go to Locate open or poor
(227) from the solenoid terminal B next connection in circuit
pigtail. Disconnect to (1075) step. 97EFS between
connector (1075) from terminal A. connector (227) and
the engine fan control connector (1075),
connector. Measure then repair.
resistance from (227)
terminal B to (1075)
terminal A.
2. Off Measure resistance (227), >100K Go to Locate short to ground
from (227) terminal B to terminal B ohms. next in circuit 97EFS then
ground. to ground. step. repair.
3. Off Disconnect connector (228), >100K Go to Locate short to ground
(228). Measure terminal B ohms. next in circuits 23D, 23B,
resistance from (228) to ground. step. 23, 13U or 13, then
terminal B to ground. repair.
4. On Turn on key switch. (227) 12 ± 1.5 Go to Locate open or poor
Measure voltage from terminal A volts. next connection in circuits
(227) terminal A to to ground. step. between connector
ground. (227) and key switch
(40), and circuit 23B,
then repair.
5. On Reconnect (227) to Solenoid Go to Replace fan solenoid.
solenoid, install a jumper energizes. next
from (1075) terminal A step.
to ground. Does the
solenoid energize?
6. Off The fan solenoid switch
circuits check good.
Reconnect (227) and
(1075).

Testing A/C Compressor High Pressure Switch (228) and Circuits

Refer to HORTON and KYSOR ENGINE FAN WITH I6 HEUI ENGINE circuit diagrams in CTS-5298 or S08225.

Before beginning this test procedure, inspect all connectors for loose or damaged pins, wires, etc.

NOTE – Perform preceding test, Testing Fan Solenoid and Circuits, before performing this test.

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Table 41 Testing A/C compressor High Pressure Switch (228) and Circuits
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connectors A/C <5 ohms. Go to Replace switch.
(228) and (379). At A/C pressure next
pressure switch, measure switch. step.
resistance across the
switch terminals. (If you
suspect the switch is
not opening at 300 PSI,
replace switch.)
2. Off Measure resistance from (379) <5 ohms. Go to Locate open in circuit
(379) terminal 33, circuit terminal 33 next 23A between (400)
23A to (228) terminal A. to (228) step. and (228), then repair.
terminal A.
3. Off Measure resistance from (379) >100K Go to Locate short to ground
(379) terminal 33 to terminal 33 ohms. next in circuit 23A, then
ground. to ground. step. repair.
4. On Turn on key switch. (228) 12 ± 1.5 Go to Locate open or poor
Measure voltage from terminal B volts. next connection in circuits
(228) terminal B to to ground. step. between connector
ground. (228) and key switch
(40), then repair.
5. Off The A/C high pressure
switch circuits check
good. Reconnect (379)
and (228). If you suspect
the A/C switch is not
working properly, replace
the switch and test system
operation.

4. COMPONENT LOCATIONS
(2) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Right Side of Engine Cowl, Above Connector 3
(3) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Right Side of Engine Cowl, Below Connector 2
(227) Fan Solenoid. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . ... . . . . . At Front of Engine (Outside Dash Panel, Left Side, with
Cummins ISM and AHD)
(228) A/C Pressure Switch. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . On A/C Compressor
(251) CELECT 21–Way ECM Connector. . . . . . . . . . .. . . . . . At Engine Harness Near ECM (With M11E and N14E)
(273) Detroit Diesel ECM Connector . . . . . . . . . . . . . . .. . . . . . To ECM Mounted on Dash Engine Side (With Detroit
Diesel)
(379) CEC Module Connector. . . . . . . . . . . . . . . . . . . . . . .. . . . . . On Engine (With I6 HEUI)
(400) OEM Interface Connector. . . . . . . . . . . . . . . . . . . . .. . . . . . On Engine (With C-10, C-12 and 3406E)
(659) Engine Fan Override Switch. . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(1074) Engine Fan Control Connector. . . . . . . . . . . . . .. . . . . . On Engine (With I6 HEUI)
(1093) ECM Interface Connector. . . . . . . . . . . . . . . . . . . .. . . . . . On Engine (With ISM and AHD)

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Figure 69 Engine Wiring at Dash Panel, With Fan Solenoid

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1. SEE FOLLOWING FIGURES FOR DETROIT DIESEL SERIES 60 OR CUMMINS N14E

ENGINE HARNESS
2. ENGINE HARNESS
3. CONNECTOR (3)
4. CIRCUIT 23, CONNECTOR (2)
5. FAN SOLENOID
6. FAN SOLENOID CONNECTOR (227)

Figure 70 Engine Fan Wiring, Detroit Diesel Series 60

1. ECM CONNECTOR
2. TO OTHER SIDE OF ENGINE
3. TO ENGINE WIRING AT DASH PANEL
4. ENGINE HARNESS
5. TO TRANSMISSION

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 5 ELECTRICAL TROUBLESHOOTING FANS 175

Figure 71 Engine Fan Wiring, Detroit Diesel Series 60

1. ENGINE HARNESS TO OTHER SIDE OF ENGINE
2. HIGH PRESSURE CUT–OUT CIRCUITS 23C AND 23–GB (228)
3. AIR HOSE TO FAN

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Figure 72 Engine Fan Wiring, Cummins N14E

1. A/C HIGHPRESSURE CUT-OUT CIRCUITS 23 AND 23D (228)
2. TO FAN SOLENOID
3. 21–WAY ECM CONNECTOR (251)

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 5 ELECTRICAL TROUBLESHOOTING FANS 177

Figure 73 Engine Fan Wiring, Caterpillar C10, C12

1. ECM CONNECTOR (400)
2. GROUND STUD CIRCUIT 11–GS
3. CIRCUITS 23C AND 23–G
4. A/C HIGH PRESSURE CUT-OUT (228)
5. ENGINE HARNESS
6. TO ENGINE WIRING AT DASH PANEL

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Figure 74 Engine Fan Wiring, Caterpillar 3406E

1. ECM CONNECTOR (400)
2. GROUND STUD CIRCUIT 11–GC AND 23–GA
3. ENGINE HARNESS TO OTHER SIDE OF ENGINE
4. TO ENGINE WIRING AT DASH PANEL

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Figure 75 Engine Fan Wiring, Caterpillar 3406E (Viewed From Top of Engine)
1. CIRCUIT 77C
2. ENGINE HARNESS
3. FAN CIRCUITS TO ENGINE WIRING AT DASH PANEL
4. A/C HIGH PRESSURE CUT–OUT (228)

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Figure 76 Engine Fan Wiring, Cummins ISM

1. 31–WAY INTERFACE CONNECTOR (1093)
2. 50–WAY OEM INTERFACE CONNECTOR (1091)
3. A/C HIGH PRESSURE CUT–OUT
4. CIRCUITS 23A AND 23D (228)
5. TO FAN CIRCUITS, ENGINE WIRING AT DASH PANEL
6. TO ENGINE WIRING AT DASH PANEL

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Figure 77 Engine Fan Wiring, Cummins AHD

1. A/C HIGH PRESSURE CUT-OUT CIRCUITS 23A AND 23D (228)
2. 50–WAY ECM OEM CONNECTOR (1091)
3. 31–WAY ECM INTERFACE CONNECTOR
4. TO FAN SOLENOID CIRCUITS AT ENGINE WIRING ON DASH
5. ENGINE HARNESS TO OTHER SIDE OF ENGINE

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Figure 78 Engine Fan Wiring, International I6 HEUI

1. TO FAN SOLENOID CIRCUITS AT ENGINE WIRING ON DASH
2. ENGINE FAN CONTROL CONNECTOR (1075)
3. CEC CONNECTOR (379)
4. TO ENGINE WIRING ON DASH

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Figure 79 Engine Fan Wiring, International I6 HEUI

1. A/C HIGH PRESSURE CUT-OUT SWITCH
2. CIRCUITS 23A AND 23B (228)
3. JUMPER WITH NO A/C
4. ENGINE HARNESS

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Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .187

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .188
2.1. ECM POWER CIRCUITS.. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .188
2.2. VEHICLE SPEED SENSOR. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .188
2.3. COOLANT LEVEL SENSOR. . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . .188
2.4. ATA DATALINK CONNECTOR.. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .189
2.5. J1939 DATA LINK. . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . .189
2.6. CRUISE CONTROL. .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .189
2.7. SERVICE BRAKE SWITCH.. .. .. .. .. .. . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .190
2.8. CLUTCH SWITCH.. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .190
2.9. VEHICLE SPEED SENSOR. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .190
2.10. SPEEDOMETER/TACHOMETER CONNECTOR. . .. .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. .190
2.11. THROTTLE POSITION SENSOR.. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .191
2.12. ENGINE BRAKE. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. .191
2.13. ANTILOCK BRAKE SYSTEM. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .192
2.14. IDLE SHUTDOWN TIMER. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .192

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .193
3.1. DETERMINING FAULT CODES.. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .193
Reading Flash Codes .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .193
3.2. IMPORTANT STEPS BEFORE TESTING. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .195
3.3. INSPECTING ELECTRICAL CONNECTORS. . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .195
Visual Inspection. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .195
Performing Electrical Tests At International Connection (400) To ECM.. .. .. .. .. .. .. .. .. 196
Test Leads.. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .196
Replacing International Components. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . .196
3.4. TESTING HELLA RELAY. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .196
3.5. TESTING ELECTRICAL POWER SUPPLY TO ECM. .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. .197
Testing Switched Power Supply To ECM. . . . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .. . . . . .197
Testing Unswitched Battery Feed To ECM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..197
3.6. DIAGNOSTIC CONNECTOR (137) AND DATA LINK CIRCUITS. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .198
Testing Diagnostic Connector Power and Ground Circuits. . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .198
Testing Diagnostic Connector and Speedometer/Tachometer Positive and Negative
Data Link Circuits.. . .. . .. . . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . . .. . .. . .. . . .. . .. . . .. . .. . .. . . .. . .. . .199
3.7. THROTTLE POSITION SENSOR (TPS). . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .201
Testing Throttle Position Sensor (TPS) and Circuits. . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .201
3.8. VEHICLE SPEED SENSOR (VSS). .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .202
Inspecting And Adjusting the Adjustable Vehicle Speed Sensor (VSS). . . . . . . . . . . . . . . . . .202
Testing Vehicle Speed Sensor (VSS).. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .202
Testing Vehicle Speed Sensor (409). .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .203
Testing Vehicle Speed Sensor To ECM Circuits. .. . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .203
3.9. CRUISE AND PTO CONTROLS. . . . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .204
Testing Cruise On/Off Switch and Circuits. . .. . .. . .. . . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . . .. . .. . .205
Testing Cruise Set/Resume Switch and Circuits. . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .205
3.10. CLUTCH SWITCH (55).. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 206
Testing Clutch Switch and Circuits.. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .206

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Adjusting Clutch Switch. . .. .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . ..207

3.11. SERVICE BRAKE SWITCH (141). . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . .207
Testing Service Brake Switch and Circuits.. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. ..207
3.12. LOW COOLANT SENSOR.. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. .208
Testing Low Coolant Sensor.. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . ..209
3.13. ENGINE BRAKE CONTROLS. . . . .. . . . .. . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. .210
Testing Engine Brake Switches and Circuits. . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . .210
Testing J1922 Circuits. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .211

4. COMPONENT LOCATIONS. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . ..212

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 187

1. DESCRIPTION
The C-10, C-12 and 3406E engines use the ADEM III electronic controller. This controller provides engine
and vehicle functions including:

ENGINE FUNCTIONS

A. Electronic Governing*
B. Fuel/Air Ratio Control*
C. Injection Timing Control*
D. Service Diagnostics**
E. Torque Rise Shaping*
F. Trip Data Recording*

*Caterpillar System

**Caterpillar/International System

VEHICLE FUNCTIONS

A. Cruise Control*
B. Data Links*
C. Engine Brake Controls*
D. Engine Protection System*
E. Idle Shutdown Timer*
F. Progressive Shifting*
G. PTO Controls*
H. Vehicle Speed Limiting*

*Caterpillar/International System

Certain programmable parameters that affect the engine electronic control systems may be changed with
electronic service tools.

The parameters are stored in the system Electronic Control Module (ECM) and are protected from
unauthorized change by passwords. The programmable parameters are either “System Parameters” or
“Customer Parameters.”

System Configuration Parameters are set at the factory and affect emissions and horsepower ratings within a
family of engines. Factory passwords must be obtained and used to change System Configuration Parameters.

Customer Selectable Parameters are variable, and are used to specify operating parameters for: cruise
control, PTO operation, vehicle speed limits, progressive shifting, type of engine protection system, RPM
and horsepower ratings within the engine family . Customer passwords are needed to change Customer
Parameters.

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188 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

Since each C-10, C-12 or 3406E control system is electronically programmable to individual owner
specifications, the operating parameters will vary from vehicle to vehicle.

Some of these parameters may cause the engine to operate in a way that the driver (or service technician)
does not expect, if proper training has not taken place. This may lead to power or performance complaints
and/or service time, when the engine is operating correctly.

International provides an ATA Diagnostic connector (137) for connecting an Electronic Service Tool (EST) to
the electronic engine control system. The Diagnostic connector is located on the instrument panel left side.

2. OPERATION
Refer to CATERPILLAR C-10 and C-12 and 3406E ENGINE circuit diagrams CTS-5298 or S08225.

This section describes specific electrical operation of International installed circuits and components,
referencing specific circuits, connectors and components by number.

2.1. ECM POWER CIRCUITS

With the key switch on, the ECM receives (12 volt DC) operating power from the vehicle batteries through
International engine harness connector (400) terminal 70. Battery power to the ECM comes fuse F6-D, when
the key switch is in the ignition position.

Battery power from the (+) battery terminal of the cranking motor solenoid is always applied on circuits 97B
and 97C through connector (400) terminals 52 and 53 to the ECM. These circuits are protected by fuses
(217) and (218).

Refer to 12V CHARGING and CRANKING WITH CATERPILLAR C-10, C-12 and 3406E ENGINES circuit
diagrams CTS-5298 or S08225.

The ECM uses this power to maintain a portion of memory used for customer trip data accumulators.
Disconnecting this circuit does not affect engine operation or factory/customer parameters or logged diagnostic
codes. Refer to the Caterpillar Troubleshooting Manual for additional information on this feature.

2.2. VEHICLE SPEED SENSOR

The ECM receives the AC signal from the vehicle speed sensor (1099) on circuits 97AJ and 97AK, through
connector (1093), and sends a signal to the vehicle speedometer. The ECM also sends the signal to drive
the vehicle tachometer.

Two types of sensors are available. The threaded (adjustable) sensor is used on most transmissions.

A push-in (non-adjustable) sensor may be used on some transmissions.

2.3. COOLANT LEVEL SENSOR

The coolant level switch is a fluid level actuated switch that sends two signals to the ECM, thus providing a
warning when coolant is being lost. It is mounted in the coolant surge tank. The coolant level switch is an
electronic switch that operates on the electrostatic or capacitance principle and cannot be tested with a
multimeter. The probe extends into the coolant and produces a change in capacitance when coolant displaces
air immediately surrounding the probe. This change is converted in the switch to an on/off solid state switch
closure indicating the absence or presence of coolant. The switch is electrically insulated providing a slick,
non-fouling surface as well as good electrical characteristics to prevent current flow into the coolant. The low

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 189

coolant level switch connects to the engine harness at connector (249). Four circuits from connector (402)
connect the low coolant switch to the ECM through the 21–way ECM connector (400).

The coolant level switch (402) receives a 5 volt signal on circuit 34B(5V) from the ECM (400). When the
coolant level is above the probe, the switch sends a high signal (3.5 volts minimum) on circuit 34A and a low
signal (0.5 volt maximum) on circuit 34 to the ECM (400).

When the coolant level is below the probe, the switch sends a low signal (0.5 volt maximum) on circuit 34A and
a high signal (3.5 volts minimum) on circuit 34 to ECM (251).

The low coolant level switch is grounded through circuit 34–G to ECM (251).

NOTE – The low coolant level switch cannot be tested with a multimeter in the ohmmeter mode. This is
due to the fact that the switch is an electronic switch and not a mechanical switch.

2.4. ATA DATALINK CONNECTOR

Connector (137) is located on left instrument panel. Four of the six connector cavities have terminals. Those
terminals and connecting circuits are as follows:

A. Circuit 98A(+) is the positive data link connection, and it is fed by the positive data link connector
(514), connector (190), circuit 98B(+) and circuit 98(+) coming from the ECM connector (400).
B. Circuit 98C(-) is the negative data link connection, and it is fed by the negative data link connector
(515), circuit 98B(-), connector (190), and circuit 98B(-) coming from the ECM connector (400).
C. Circuit 97DL is a 12 volt feed and is fed from bat stud (B1) circuit 14W, circuit 14AA, 20A fuse
F5–D, and circuit 97DL. Thus it provides power for the electronic service tool.
D. Circuits 11–GR and 11–GT connect to the panel light ground adapter (506) and provide a ground
for the electronic service tool.

2.5. J1939 DATA LINK

The ADEM III controller provides a J1939 data link for use with some types of transmissions and service tools.

A. Circuit 98YL(+) is the positive data link connection. It originates from ECM connector (400),
terminal 50. The circuit is connected to J1939 terminating resistor connector (1098), terminal A
and J1939 backbone connector (1097), terminal A.
B. Circuit 98GN(-) is the negative data link connection. It originates from ECM connector (400),
terminal 34. The circuit is connected to J1939 terminating resistor connector (1098), terminal C
and J1939 backbone connector (1097), terminal B.
C. Circuit 98SHD is the data link shield connection. It originates from ECM connector (400), terminal
42. The circuit is connected to J1939 terminating resistor connector (1098), terminal B and J1939
backbone connector (1097), terminal C.

2.6. CRUISE CONTROL

The cruise control switches are used as idle controls when the vehicle road speed is not present (this is a
customer selected parameter). Refer to the Operators Manual furnished with the vehicle for cruise control
operating instructions. Refer to circuit diagram CATERPILLAR C-10, C-12 or 3406E — CRUISE CONTROL in
CTS-5298 or S08225.

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190 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

The cruise on/off switch is lighted to allow for easy location in the dark. Cruise on/off switch circuit 97AE is an
input to the ECM at connector (400) terminal 20. The ground side of the on/off switch is connected through
circuits 97–GC, 97–GB, 97–GA and 97–G to connector (400) terminal 5. With the switch on, the ECM sees 0
volts at connector (400) terminal 20. With the switch off, the ECM sees 5 volts at connector (400) terminal 20.

The cruise set/resume switch is lighted to allow for easy location in the dark. Set/resume switch terminal 2 is
connected to the ECM through circuits 97–GB, 97–GA and 97–G to the connector (400) terminal 5. Set/resume
switch Set terminal 3 is an input (circuit 97AB) to the ECM through connector (400) terminal 35. Set/resume
switch Resume terminal 1 is an input (circuit 97AA) to the ECM through connector (400) terminal 44.

With the set/resume switch in the set position, the ECM sees 0 volts at connector (400) terminal 35 and
5 volts at terminal 44.

In resume position, the ECM sees 5 volts at connector (400) terminal 35 and 0 volts at terminal 44.

In the set/resume neutral position, the ECM sees 5 volts at both connector (400) terminals 35 and 44.

2.7. SERVICE BRAKE SWITCH

Circuit 97AL is an input to the ECM through connector (400) terminal 45. The ground or common side of the
service brake switch is connected through circuits 97–GF, 97–GA and 97–G to connector (400) terminal 29.
With service brakes released (switch closed), the ECM sees 0 volts at connector (400) terminal 5. Applying
the brakes opens the switch, and the ECM sees 5 volts at terminal 14.

2.8. CLUTCH SWITCH

This normally open switch is adjusted to be closed while the clutch pedal is released.

The clutch switch connects to the cab harness at connector (294). Clutch switch circuit 97AH is an input to the
ECM through connector (400) terminal 22. The ground side of the clutch pedal switch is grounded through
circuits 97–GH, 97–GA, and 97–G to connector (400) terminal 5. With the driver’s foot off the clutch pedal
(switch closed), the ECM sees 0 volts at terminal 22. When the driver depresses the clutch pedal (switch
opens), the ECM sees 5 volts at terminal 22.

2.9. VEHICLE SPEED SENSOR

Connector (409) is located at the rear of the transmission. The sensor contains a permanent magnet that
creates a magnetic field that is interrupted by the teeth on the speedometer output gear. As the rotating
speedometer gear teeth repeatedly interrupt the sensor magnetic field, a variable AC voltage is generated
and transmitted to the ECM. From sensor connector (409) circuits 97AJ and 97AK carry the signal to ECM
connector (400) terminals 32 and 33.

2.10. SPEEDOMETER/TACHOMETER CONNECTOR

Data link positive connector (514) terminal C is connected by circuit 47/48(+) to speedometer/tachometer
connector (421). Data link positive connector (514) terminal A is connected by circuit 98A(+) to the ATA data
link connector (137) terminal A. ATA data link connector (137) can be used to access information on the
data link using an electronic service tool.

Data link negative connector (515) terminal C is connected by circuit 47/48(-) to speedometer/tachometer
connector (421). Data link negative connector (515) terminal A is connected by circuit 98C(-) to the ATA data
link connector (137) terminal B. ATA data link connector (137) can be used to access information on the
data link using an electronic service tool.

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 191

2.11. THROTTLE POSITION SENSOR

The pedal mounted Throttle Position Sensor (TPS) is used to provide a throttle signal to the ECM. Sensor
output is a constant frequency signal with a pulse width that varies with throttle position. This output signal
is referred to as either “Duty Cycle” or a “Pulse Width Modulated” (PWM) signal and is expressed as a
percentage between 0 and 100%.

The pedal mounted throttle position sensor is attached directly to the throttle pedal assembly and requires
no adjustment. This sensor can be replaced separately from the throttle pedal assembly, however, an
incorrectly calibrated pedal mounted throttle position sensor assembly cannot be calibrated — the pedal
assembly must be replaced.

Refer to circuit diagram CATERPILLAR C-10, C-12, or 3406E — CRUISE CONTROL in CTS-5298 or S08225.

The TPS connects to the cab harness at three-pin connector (404). When the ECM is powered (key switch
on), the TPS receives operating voltage (8 volts) at terminal A on circuit 99A which is connected to ECM
connector (400) terminal 4. TPS terminal B is grounded by circuit 99–GA, 97–GA, 97–G through ECM
connector (400) terminal 5.

TPS terminal C outputs the variable throttle position signal on circuit 99 to ECM connector (400) terminal 66.

The pedal mounted TPS should produce a Duty Cycle of 10 to 22 percent at low idle and 75 to 90 percent at
full throttle. An electronic service tool can be used to monitor the signal. The percent duty cycle is translated in
the ECM into a throttle position percentage of 3 to 100%.

2.12. ENGINE BRAKE

These Caterpillar engines come with an engine brake. This manual discusses only engine brake control
circuits and components installed by International: the engine brake on/off switch (434), the engine brake
selector switch (433) and the connecting circuits. The International– installed clutch switch (294) and service
brake switch (141) also provide inputs to the engine brake control system.

For a complete description of engine brake operation, refer to the appropriate Caterpillar Service Manual.

There are two owner selected engine brake operation modes, which are COAST and LATCH.

If the COAST mode (standard mode) is selected, the engine brake operates when:

• Engine speed is over 800 rpm.

• The driver’s foot is off the throttle pedal (throttle position less than 7%).
• Clutch pedal is not depressed.
• The service brake pedal is depressed (engine brake only operates while service brake is applied).
• The cruise control switch can be in the on position, although it will be disabled by applying the service brake.

If the LATCH mode is selected, the engine brake operates when:

• Engine speed is over 800 rpm.

• The driver’s foot is off the throttle pedal (throttle position less than 7%).
• Clutch pedal is not depressed.
• The cruise control switch must be off.

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192 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

• The engine brake operates when the driver applies the service brake, but the engine brake continues
to operate (latches on, so to speak) after the driver takes his foot off the brake. The engine brake stays
engaged (latched on) until one of the other ECM inputs changes: clutch pedal depressed, throttle pedal
depressed, engine speed drops below 800 rpm or the brake pedal is depressed a second time.

Control of the engine brake is shared by the driver and the ECM. The driver turns the engine brake on or off
and selects how much engine brake is desired (number of cylinders). The ECM monitors certain engine
parameters, then enables the engine brake system when all conditions are acceptable.

An on/off switch (434) is used to enable (turn on) the engine brake control system. With the on/off switch
closed, the circuit between ECM connector (400) terminal 5 and the engine brake selector switch terminal 2
is complete.

The engine brake selector switch (433) has three circuits: Low, Medium and a common or ground circuit
connected to the engine brake on/off switch.

Selector switch terminal 2 is connected by circuit 24A to the engine brake on/off switch (434) at terminal 5.
When the on/off switch is on, the circuit between the engine brake selector switch (433) terminal 2 and ECM
connector (400) terminal 5 is complete.

With the selector switch (433) in the Low position, the ECM sees a 0 volt signal at connector (400) terminal 23
and a 5 volt signal at terminal 40.

With the selector switch (433) in the Medium position, the ECM sees a 0 volt signal at connector (400) terminal
40 and a 5 volt signal at terminal 23.

With the selector switch (433) in the High position, the ECM sees a 0 volt signal at connector (400) terminals
40 and 23.

2.13. ANTILOCK BRAKE SYSTEM

On vehicles with Antilock Brakes (ABS), the ABS controller is connected to the ECM through J1922 connector
(403). This connection allows the ABS controller to communicate with the ECM by serial data circuits 98Z(+)
and 98Y(-). These circuits are a twisted wire pair. This allows the ECM to turn off the engine brake when the
ABS system detects that a vehicle wheel is encountering a slippery road surface.

2.14. IDLE SHUTDOWN TIMER

This feature helps improve fuel consumption by limiting idle time. The “shutdown time” is a customer specified
parameter, and may be from 3 to 1440 minutes. Programming the time to zero shuts the timer off.

The timer is activated and the countdown (from the customer selected time) begins when:

• The vehicle speed is zero.

• The engine is warmed up.
• The engine is not under load (with or without the park brake set).

Ninety seconds before the programmed time is reached, the Yellow Serv/Check Engine light will begin to flash
rapidly. If the driver moves the clutch (294) or service brake (141) pedal during this 90–second time period, the
clutch switch (294) or the brake switch (141) contacts will open up and the timer will be overridden until it is
reset. The timer is reset and begins counting over by moving the vehicle a short distance.

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 193

A code (Override of Idle Shutdown Timer) will be logged when the driver overrides the timer within the
90–second time period. If the timer is activated and allowed to shut down the engine, then a code (Idle
Shutdown Timed Out) will be set. These codes record an event — they do not indicate a fault in the system.

IMPORTANT – Note that the system shuts the engine down, but does not turn off power to the vehicle.

3. TROUBLESHOOTING
A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 -
ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not
covered in detail. It is assumed that the technician knows to check for a malfunctioning switch,
relay, or solenoid.

During normal vehicle start-up, turning the key to the on position causes the Serv/Check Engine light to come
on as a system test. The light remains on for about six seconds, then goes off. If the Serv/Check Engine light
stays on after the initial start-up, the ECM has detected a problem with the system.

All C-10, C-12 and 3406E equipped vehicles have a yellow Serv/Check Engine light located in the left gauge
cluster. This light communicates engine status.

If during vehicle operation, the Serv/Check Engine light comes on, that indicates an active fault is present. The
light will remain on, but blink approximately every five seconds for a brief 1/2 second.

3.1. DETERMINING FAULT CODES

The EZ-Tech™, PRO-LINK 9000®, or Caterpillar electronic service tools (EST) can be used to identify logged
fault codes. Refer to the EST manual for operating instructions.

The yellow Serv/Check Engine light can be used to read fault codes by following the procedure in the following
paragraph.

Reading Flash Codes

KEY ON — ENGINE OFF PROCEDURE

NOTE – All Caterpillar flash codes are two digit numbers.

1. Turn the key to the on position. The yellow Serv/Check Engine light will turn on for approximately five
seconds, then turn off for several more seconds, then begins to FLASH any logged codes.

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194 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

2. The yellow Serv/Check Engine light will FLASH the first digit. At the end of first digit there is a one
or two second pause.

3. The yellow Serv/Check Engine light will FLASH the second digit. At the end of the second digit there will
be a two or three second pause before the next fault code number is FLASHED.

4. The second and all successive fault codes will FLASH until all codes have been FLASHED. It will stop
FLASHING after the last code has been flashed. To see the fault codes again, repeat the process.

5. Flash code 55 indicates that there are no logged diagnostic codes. For a listing of Caterpillar Flash
codes, refer to the Caterpillar Electronic Troubleshooting manual. Codes are also listed in the EZ- Tech
or PRO-LINK 9000 manual.

ENGINE RUNNING PROCEDURE

NOTE – All Caterpillar flash codes are two digit numbers.

6. Begin procedure with engine off.

7. Start engine and allow to run at low idle for about 30 seconds.

8. Turn cruise on/off switch to off position.

9. Hold cruise set/resume switch in either position until codes begin to FLASH, then release.

10. The yellow Serv/Check Engine light will FLASH the first digit. At the end of the first digit there is a one
or two second pause.

11. The yellow Serv/Check Engine light will FLASH the second digit. At the end of the second digit there will
be a two or three second pause before the next fault code number is FLASHED.

12. The second and all successive fault codes will FLASH until all codes have been FLASHED. It will stop
FLASHING after the last code has been flashed. To see the fault codes again, repeat steps 4 through 6.

13. Flash code 55 indicates that there are no logged diagnostic codes. For a listing of Caterpillar flash
codes, refer to the Caterpillar Electronic Troubleshooting manual. Codes are also listed in the EZ-Tech
or PRO-LINK 9000 manual.

This section includes diagnostic tables for International– installed circuits and components that are part
of the Caterpillar electronic engine control system.

To begin the process, refer to the appropriate Caterpillar Electronic Troubleshooting Manual and
follow their directions.

If the Caterpillar diagnostics indicate that an International circuit is suspect, use the diagnostic tables included
in this section for a step-by-step procedure. Refer to the appropriate circuit diagram for CATERPILLAR C-10,
C-12 or 3406E ENGINES IN CTS-5298 or S08225.

The EZ-Tech or PRO-LINK 9000 EST’s with the Caterpillar programs can be used to read fault codes,
customer and engine parameters and monitor various switches and sensors.

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 195

3.2. IMPORTANT STEPS BEFORE TESTING

1. Gather information by talking to the driver if possible. Try to determine the exact symptoms by gathering
relevant information:
a. What happened and when?
b. Under what conditions?
c. When did the symptoms begin?
d. What else occurred at that time?

2. Verify the problem. Is the complaint due to misunderstood customer selected parameters? Use an EST
to review customer selected parameters.

3. Check for and record any logged fault codes.

a. Do the logged codes correlate to probable causes?
b. Were the codes logged about the same time as the symptoms appeared? Were the codes logged
repeatedly?
c. Are the logged codes related to other symptoms? Do they have a common cause?

4. Avoid Preconceived Ideas! Eliminate any non-electrical causes for the problem first (contaminated
fuel, clogged air filters, etc.).

3.3. INSPECTING ELECTRICAL CONNECTORS

Visual Inspection

The troubleshooting guide requires checking specific connectors. Use the following steps to determine if
the connector is causing the problem. If a defective condition is found, make the necessary corrections
and continue the process.

1. Check the connector lock mechanism or retaining screw. Make sure the connector is capable of
properly locking the connector together.

2. Perform a 10 pound pull-test on each terminal/wire in the connector. Each terminal/wire assembly
should easily withstand 10 pounds of pull and remain in the connector. This test determines (A) if the
wire is properly in the terminal and (B) if the terminal is properly inserted into the connector. Correct
any defects noted.

3. Visually inspect wiring. Inspect for worn or damaged wires. Check for pinched or damaged harness.

4. Visually inspect connectors. Verify that pins and sockets are free of corrosion, dirt or other contaminants
and damage. Verify correct alignment and location of terminals in the connector.

5. Check individual pins and sockets. This is especially important with an intermittent symptom. Using a
new pin, insert the pin into each socket, one at a time, checking for a good grip on the pin by the socket.
Repeat for each pin on the mating side of the connector, using a new female terminal for the test.

6. Inspect Engine Ground Stud. Inspect this ground and other related grounds for clean, tight connections
that are free of corrosion and/or other defective conditions.

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196 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

Performing Electrical Tests At International Connection (400) To ECM

International OEM connector (400) mates with Caterpillar ECM connector J1. This is a Deutsch 40–pin
connector, with the International side having female terminals (sockets) and the Caterpillar side having pins.

NOTE – No tests in this manual require testing “into” the Caterpillar J1 connector.

When testing the International side of connector (400), never insert meter probes into the sockets, as the
probes will damage the sockets. Always use test leads of the type described in Test Leads, in the following
paragraph. The test leads must fit snugly into the sockets without expanding the sockets.

Test Leads

To construct test leads, attach an insulated alligator clip to a suitable length of 16 gauge wire. On the other
end, use Deutsch HDT-48–00 Crimp Tool to install male terminal 1651958C1.

Signal Reading Probes, Caterpillar part number 7X1710, can also be used.

Replacing International Components

When replacing electrical switches, connectors (including pins and sockets), relays or other components, use
only approved International replacement parts. Many of the switches have gold or silver plated contacts and
some of the connectors have gold plated terminals. By using correct replacement parts, you maintain the
design integrity of the system.

All of the relays and other solenoids installed by International are suppressed to prevent voltage spikes from
damaging electrical components. Again, use only International replacements for these components.

3.4. TESTING HELLA RELAY

International circuits use suppressed Hella relays for controlling power to load devices. The suppression
feature (a resistor circuit parallel to the relay coil) prevents voltage spikes from damaging electronic
components in the vehicle. These relays must be replaced with approved International parts.

The part number and relay circuit diagram are embossed on the relay body. The terminals are numbered on
the relay in the same manner as in the circuit diagrams.

Relay Test Procedure

1. With relay removed, measure resistance between terminals 30 and 87A. If resistance is less than 5
ohms, go to step 2; otherwise replace the relay.

2. Measure resistance between terminals 30 and 87. If resistance is 100K ohms or more, go to step 3;
otherwise replace the relay.

3. Using 12V battery source and test leads, connect (+) lead to terminal 85 and (-) lead to terminal 86. If relay
energizes with an audible click sound, go to step 4; otherwise replace the relay.

4. While relay is energized, measure resistance between terminals 30 and 87. If resistance is less than 5
ohms, go to step 5; otherwise replace the relay.

5. While relay is energized, measure resistance between terminals 30 and 87A. If resistance is 100K ohms or
more, the relay is good; otherwise replace relay.

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3.5. TESTING ELECTRICAL POWER SUPPLY TO ECM

Procedure for Testing Switched Power Supply To ECM tests the switched battery power circuits to the ECM
(key on).

Procedure for Testing Unswitched Battery Feed To ECM tests the unswitched battery power circuits to the ECM.

Testing Switched Power Supply To ECM

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

Table 42 Testing Switched Power Supply To ECM

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove and check fuse F6-D <1 ohm. Go to Locate cause
F6-D for open condition. next step. of overload
Fuses OK? condition, then
repair. Replace
fuse(s).
2. Off/ Disconnect connector (400), 97L to 12 ± 1.5 Go to Loacate cause of
On (400) from ECM. Re-install gnd. volts. next step. incorrect voltage
fuse F6-D. Turn key on on circuit 13D.
and measure voltage to
ground at terminal 70,
circuit 97L.
3. On Switched voltage to (400), 12 ± 1.5 ECM Locate open or
ECM checks good. At between volts. gnd. poor connection
connector (400), measure 97-G and circuit in ground circuit
voltage between terminals 97L. 97-GB 97-GB, between
5 (circuit 97-G) and 70 checks connector (400)
(circuit 97L). good. and engine ground
stud, then repair.

Testing Unswitched Battery Feed To ECM

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

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Table 43 Testing Unswitched Battery Feed To ECM

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connector Inline fuses Not Go to next Locate cause of
(400) from ECM. Check (217) and open. step. overload condition,
inline fuses (217) and (218). then repair. Replace
(218) for open condition. fuses.
2. Off At terminal 52, circuit (400), 97B 12 ± 1.5 Go to next Locate cause of no or
97B, measure voltage to to gnd. volts. step. low voltage in circuit
ground. 97B from cranking
motor "B" terminal,
then repair.
3. Off At terminal 53, circuit (400), 97C 12 ± 1.5 Go to next Locate cause of no or
97C, measure voltage to to ground. volts. step. low voltage in circuit
ground. 97B from cranking
motor "B" terminal,
then repair.
4. Off At connector (400), (400) 12 ± 1.5 Go to next Locate open or poor
measure voltage between volts step. connection in circuit
between terminal 65, 97-GB and 97-GB between conn.
circuit 97-GB and 97B. (400) and cylinder
terminal 52, circuit 97B. head ground, then
repair.
5. Off At connector (400), (400) 12 ± 1.5 Unswitched Locate open or poor
measure voltage between volts. battery connection in circuit
between terminal 97-GJ and feed to 97-GJ between conn.
67, circuit 97-GJ and 97B. ECM (400) and cylinder
terminal 52, circuit 97B. checks head ground, then
good. repair.

3.6. DIAGNOSTIC CONNECTOR (137) AND DATA LINK CIRCUITS

Testing Diagnostic Connector Power and Ground Circuits

Table 44 Testing Diagnostic Connector Power and Ground Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove and check F5-D <1 ohm. Go to next Locate cause of
20A fuse F5-D for step overload condition,
open condition. Is fuse then repair. Replace
open? the fuse.

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Table 44 Testing Diagnostic Connector Power and Ground Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. On Re-install fuse F5-D. (137), 12 ± 1.5 Go to next Locate cause of no or
At connector (137), 97DL to volts. step. low voltage in circuit
measure voltage from ground. 97DL, then repair.
circuit 97DL to ground.
3. On At connector (137), (137) 12 ± 1.5 Power and Locate open or poor
measure voltage between volts. gnd. circuits connection in circuit
between circuit 97DL 97DL and to diagnostic 11-GR, 11-GT to
and circuit 11-GR. 11-GR. conn. (137) panel light adapter
check good. (506), then repair.

Testing Diagnostic Connector and Speedometer/Tachometer Positive and Negative Data Link Circuits

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

NOTE – A multimeter cannot be used to measure the voltage of the signal on these circuits.

Table 45 Testing Diagnostic Connector and Speedometer/Tachometer Positive and Negative Data
Link Circuits
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Disconnect conn. (400) (137), 98A >100K Go to next Locate short to
from ECM, and (421) from (+) to gnd. ohms. step. ground, then
speedometer unit. If other repair.
devices are connected at
data link connectors (514)
and (515), disconnect them.
At conn. (137) measure
resistance from terminal A,
circuit 98A(+) to ground.
2. Off At conn. (137) measure (137), >100K Go to next Locate short to
resistance from terminal B, 98C(-) to ohms. step. ground, then
circuit 98C(-) to ground. gnd. repair.
3. Off At conn. (137) measure (137) >100K Go to next Locate short
resistance between terminal between ohms. step. circuit between
A, circuit 98A(+) and terminal 98A(+) and circuits
B, circuit 98C(-). 98C(-). connected to
terminal A
98A(+), 98(+),
47/48(+) and
terminal B98C(-),
98B(-), 47/48(-),
then repair.

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Table 45 Testing Diagnostic Connector and Speedometer/Tachometer Positive and Negative Data
Link Circuits (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
4. Off At connector (400), use (137), <5 ohms. Go to next Locate open or
test lead to jumper terminal 98A(+) to step. poor connection
8, circuit 98(+) to gnd. At gnd. in circuit
connector (137) terminal 98A(+) between
A, circuit 98A(+) measure connectors (514)
resistance to ground. and (137) or
open or poor
connection
in circuit
98(+) between
connectors (514)
and (400), then
repair.
5. Off With jumper still in place (421), <5 ohms. Go to next Locate open or
at terminal 7, circuit 98(+), 47/48(+) to step. poor connection
measure resistance to gnd. in circuit 47/48(+)
ground at circuit 47/48(+) between
and connector (421). connectors (421)
and (514), then
repair.
6. Off At connector (400) use test (137) <5 ohms. Go to next Locate open or
lead to jumper terminal 8, between step. poor connection
circuit 98(+) to terminal 98A(+) and in circuit
9, circuit 98B(-). At conn. 98C(-). 98C(-) between
(137) measure resistance connectors (515)
between terminal A, circuit and (137), or
98A(+) and terminal B, open or poor
circuit 98C(-). connection
in circuit
98B(-) between
connectors (515)
and (400), then
repair.
7. Off With jumper still in place, at (421), <5 ohms. Locate open All data link
connector (421) measure 47/48 (-) in circuit circuits check
resistance between 47/48(-) to gnd. 47/48 (-) good.
and ground. between
conn. (421)
and (515),
then repair.

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 201

3.7. THROTTLE POSITION SENSOR (TPS)

Testing Throttle Position Sensor (TPS) and Circuits

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

Table 46 Testing Throttle Position Sensor (TPS) and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect TPS from cab (404), A, B, >100K Go to Replace the throttle
harness at conn. (404). At and C to ohms. next position sensor.
TPS side of (404) measure gnd. step.
resistance to gnd. at
terminals A, B and C (red,
black and white wires).
2. Off Disconnect conn. (400) (404) >100K Go to Locate short circuit,
from ECM. At (404) between ohms. next then repair.
measure resistance 99E, 99-G step.
between terminals A, B and 99.
and C (circuits 99E, 99-G
and 99). There should be
no continuity between the
three terminals.
3. Off At conn. (400), use test (404), <5 ohms. Go to Locate open or
lead to jumper terminal 29 99-GA to next poor connection in
(circuit 97-G) to gnd. At gnd. step. circuit 99-GA path to
conn. (404) and terminal ground, then repair.
B (circuit 99-GA) measure
resistance to ground.
4. Off At conn. (400), use test (404), <5 ohms. Go to Locate open or
lead to jumper terminal 99-GA to next poor connection in
29 to 37 (circuit 97-G 99. step. circuit 99 between
to 99). At connector connectors (404)
(404) measure resistance and (400), then
between terminals B and C repair.
(circuit 99-GA to 99).
5. Off At conn. (400), use test (404), <5 ohms. Go to Locate open or
lead to jumper terminal 99-GA to next poor connection in
29 to 35 (circuit 97-G to 99E. step. circuit 99E between
99E). At conn. (404) connectors (404)
measure resistance and (400), then
between terminals B repair.
and A (circuit 99-GA and
99E).

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Table 46 Testing Throttle Position Sensor (TPS) and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
6. Off/ On Connect (400) at ECM. (404), 99E 8 ± 0.5 Go to Have Caterpillar
Turn ignition on. At conn. to 99-GA. volts. next dealer diagnose the
(404) measure voltage step. ECM.
between terminals A and B
(circuit 99E and 99-GA).
7. Off Replace the throttle End test. Have Caterpillar
position sensor and dealer diagnose the
reconnect connectors. ECM.
Test system operation and
note if defect is still present.
TPS works OK?

3.8. VEHICLE SPEED SENSOR (VSS)

Inspecting And Adjusting the Adjustable Vehicle Speed Sensor (VSS)

1. Disconnect engine harness connector (250) from the sensor. Loosen the locknut and remove the sensor.
The harness connector and sensor should be free of damage or corrosion. Remove any metal shavings or
debris from the sensor.

2. To install the adjustable sensor, turn in until the sensor contacts the transmission speedometer gear, then
back out one full turn. Tighten locknut to 15 ft-lbs. (20.3 N•m). This assures that the sensor is adjusted
properly for the next test.

Testing Vehicle Speed Sensor (VSS)

To perform this test construct two test leads using terminals (1680205C1) and suitable length of 16GA wire.

WARNING – A jack must never be used alone to support vehicle. The jack may lower and
serious injury could result. Always support vehicle with floor jacks. Always block wheels to prevent
vehicle from moving.

WARNING – EXTREME CAUTION should be used to prevent personal injury resulting from
contact with rotating vehicle wheels when connecting test leads.

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 203

Testing Vehicle Speed Sensor (409)

Table 47 Testing Vehicle Speed Sensor (409)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Inspect VSS for damage and Go to next
proper adjustment before step.
performing this test.
2. Off Disconnect engine harness VSS, A to 600 to Go to next Replace the
connector (409) from VSS B 800 ohms step. vehicle speed
and use test leads to measure for the sensor (VSS).
resistance between terminal A adjustable
and B of the sensor. sensor.
1500–
3500
ohms
for the
push-in
sensor.
3. Off Measure resistance to ground VSS, A >100K Go to next Replace the
at both terminals (A and B) of and B to ohms. step. vehicle speed
the sensor gnd. sensor (VSS).
4. Off VSS sensor output test: This Go to next
test checks for proper AC step.
voltage output signal from
VSS sensor. Improper sensor
adjustment will cause low,
erratic or no output.
5. Off Block front wheels and place Go to next
rear axles on floor stands. step.
6. Off Use AC voltmeter with Go to next
sufficient length leads to avoid step.
personal contact with rotating
vehicle wheels during test.
Connect meter leads to sensor
test leads.
7. On Run engine at idle speed with VSS, A to >2.0 volts The If sensor was
transmission in high gear. B. AC. vehicle properly adjusted,
Measure voltage across the speed replace the
two sensor terminals. sensor sensor.
checks
good.

Testing Vehicle Speed Sensor To ECM Circuits

This procedure tests the International speed sensor circuits between connectors (409) and (400).

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204 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

Table 48 Testing Vehicle Speed Sensor To ECM Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect conn. (409) (409) both >100 K Go to next Locate short to
from VSS and (400) from terminals ohms. step. ground in circuit
the ECM. At conn. (409) to gnd. (97AK or 97AJ, then
measure resistance to gnd. repair.
at both terminals.
2. Off At (409) measure resistance (409), >100K Go to next Locate short circuit
between terminals. between ohms. step. between circuits
terminals. 97AJ and 97AK,
between connectors
(409) and (400), then
repair.
3. Off At conn. (400) use test (409), <5 Go to next Locate open or poor
lead to jumper terminal 97AK to ohms. step. connection in circuit
33 to ground. At conn. gnd. 97AK, then repair.
(409) measure resistance to
ground at circuit 97AK.
4. Off At conn. (400) use test (409), <5 Vehicle Locate open or poor
lead to jumper terminal 97AJ to ohms. speed connection in circuit
32 to ground. At conn. gnd. circuits 97AJ, then repair.
(409) measure resistance to and VSS
ground at circuit 97AJ. check
good.

3.9. CRUISE AND PTO CONTROLS

Refer to Caterpillar Electronic Troubleshooting Guide to diagnose a cruise system malfunction.

The EZ-Tech or Pro-Link Electronic Service Tools (EST) can be used to monitor system parameters relating
to Cruise Control operation. Use the EST to monitor operation of system switches, including the Cruise
On/Off, Set/Resume, service brake and clutch switch.

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 205

Testing Cruise On/Off Switch and Circuits

Table 49 Testing Cruise On/Off Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Disconnect conn. (435) Across <2 Go to next Replace the
from cruise on/off switch. cruise on/off ohms. step. switch.
With switch in the switch.
on position measure
resistance between
terminals 5 and 6.
2. Off Disconnect conn. (400) (435), <5 Go to next Locate open or
from ECM. Measure the 97-GC to ohms. step. poor connection
resistance between conn. ground. in circuit 97-GC,
(435), terminal 6 and or 97-GB between
ground. conn. (435) and
ground, then
repair.
3. Off At conn. (400) use test (435), 97AE <5 Cruise Locate open or
lead to jumper terminal 59 to 97-GC. ohms. on/off switch poor connection
(circuit 97AE) to terminal 5 and circuits in circuit
(circuit 97-G). At connector to (400) 97AE between
(435), measure resistance check good. connectors (435)
between circuits 97AE and and (400), then
97-GC. repair.

Testing Cruise Set/Resume Switch and Circuits

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

Table 50 Testing Cruise Set/Resume Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove conn. (436) Set/ >100K Go to next Replace set/
from cruise set/resume resume ohms step. resume switch.
switch. With switch in switch, 2
neutral position, measure to 1 and 2
resistance between switch to 3.
terminal 2 and terminals 1
and 3.
2. Off With switch in resume Set/resume <2 ohms. Go to next Replace set/
position, measure resistance switch, 1 step. resume switch.
between switch terminals 1 to 2.
and 2.

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Table 50 Testing Cruise Set/Resume Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
3. Off With switch in set position, Set/ <2 ohms. Go to next Replace set/
measure resistance resume step. resume switch.
between switch terminals 2 switch 2 to
and 3. 3.
4. Off Disconnect conn. (400) (436), <5 ohms. Go to next Locate open or
from ECM. Measure the 97-GB to step. poor connection in
resistance between conn. ground. circuit 97-GB, then
(436) terminal 2 and ground. repair.
5. Off At conn. (400), use test lead (436), <5 ohms. Go to next Locate open or
to jumper terminal 5 (circuit 97AA to step. poor connection
97-G) to 44 (circuit 97AA). 97-GB. in circuit
At conn. (436) measure 97AA between
resistance between circuits connectors (436)
97AA and 97-GB. and (400), then
repair.
6. Off At conn. (400) use test lead (436) 97AB <5 ohms. The set/ Locate open or
to jumper terminal 5 (circuit to 97-GB. resume poor connection
97-G) to 35 (circuit 97AB). switch and in circuit
At conn. (436) measure circuits 97AB between
resistance between circuits test good. connectors (436)
97AB and 97-GB. and (400), then
repair.

3.10. CLUTCH SWITCH (55)

Testing Clutch Switch and Circuits

NOTE – If the vehicle is equipped with an Allison transmission, this switch is replaced with a jumper
connection.

Table 51 Testing Clutch Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off At (294) disconnect clutch Clutch <2 Go to next If switch is not
switch lead from cab switch, A ohms. step. adjusted properly,
harness. With clutch to B. adjust and retest.
pedal released, measure Refer to Adjusting
resistance across clutch Clutch Switch. If
switch pigtail connector (A switch is adjusted
to B). Switch should read properly, replace
closed. the switch.

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Table 51 Testing Clutch Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
2. Off Depress clutch pedal while Clutch >100K Go to next If sw. is not
measuring resistance across switch, A ohms. step. adjusted properly,
clutch switch pigtail (294) to B. adjust and retest.
terminal A to B. Refer to Adjusting
Clutch Switch. If
switch is adjusted
properly, replace
the switch.
3. Off Disconnect connector (400) (294), <5 Go to next Locate open
from ECM. At connector 97AH to ohms. step. condition in cirucit
(400) use test lead to jumper ground. 97AH between
terminal 22 (circuit 97AH) connectors (294)
to ground. At connector and (400), then
(294) measure resistance to repair.
ground at circuit 97AH.
4. Off At connector (400), use test (294), <5 Go to next Locate open or
lead to jumper terminal 5 97-GH to ohms. step. poor connection
(circuit 97-G) to 22 (circuit 97AH. in circuit 97AH,
97AH). At clutch switch 97-GH, 97-GA or
harness (294) measure 97-G betweeen
resistance between circuit connectors (294)
97-GH and 97AH. and (400), then
repair.
5. Off Remove jumper from (294), >100K The clutch Locate short circuit
connector (400), but do not 97AH to ohms. switch between circuit
connect. At clutch switch 97-GE. adjustment 97AH and circuit
harness (294), measure and circuits 97-GE, then repair.
resistance between circuits check OK.
97AH and 97-GE.

Adjusting Clutch Switch

The clutch switch should be mounted so that the switch actuator makes contact with the clutch pedal arm when
the arm is depressed 0.5 inch at the point of actuator contact. The bracket can be bent forward or backward for
adjustment. An audible click (switch closing) should be heard when the pedal is released.

3.11. SERVICE BRAKE SWITCH (141)

Testing Service Brake Switch and Circuits

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

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208 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

Table 52 Testing Service Brake Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove conn. (141) from Brake >100K Go to next Replace the
service brake switch. With switch ohms. step. brake switch.
brakes released, measure to gnd.
resistance to ground at at each
each switch terminal (not terminal.
the harness connector
side).
2. Off With (141) removed from Across <2 ohms. Go to next Replace the
service brake switch, and switch step. brake switch.
service brakes released, terminals.
measure resistance across
switch terminals.
3. Off With vehicle air pressure Across >100K Go to next Replace the
>80 PSI, apply service switch ohms. step. brake switch.
brakes while measuring terminals.
resistance across the brake
switch terminals.
4. Off Disconnect conn. (400) (141), 97AL <5 ohms. Go to next Locate open or
from ECM and do not to ground. step. poor connection
reconnect (141) to switch. condition in
Use test lead to jumper circuit 97AL
conn. (400) terminal 45 between
(circuit 97AL) to gnd. connectors
At brake switch (141), (141) and (400),
measure resistance to gnd. then repair.
at circuit 97AL.
5. Off At conn. (400), use test (141), <5 ohms. Go to next Locate open or
lead to jumper terminal 5 97-GF to step. poor conn. in
(circuit 97-G) to terminal 97AL. circuit 97-GF,
45 (circuit 97AL). Measure 97-GA, or
resistance between conn. 97-G between
(141) circuit 97AL and connectors
97-GF. (141) and (400),
then repair.
6. Off With conn. (400) (141), 97AL >100K The brake Locate short
disconnected and jumpers to 97-GF. ohms. switch and circuit between
removed, at (141) measure circuits circuit 97AL and
resistance between circuits check OK. circuit 97-GF,
97AL and 97-GF. then repair.

3.12. LOW COOLANT SENSOR

NOTE – If the customer has elected to turn Engine Protection Feature off, this sensor is not active.

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Testing Low Coolant Sensor

NOTE – Do not use meter to test low coolant sensor. It may cause damage to the circuit board located
in the sensor.

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

Table 53 Testing Low Coolant Sensor Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connector (400) >100K Go to Locate short
(400) from Cummins between 34B, ohms. next between any circuits
connector. Disconnect 97-G, 34A step. where resistance
(402) from low coolant and 34 and all between terminals
switch. At connector other circuits. is less than 100K
(400) measure resistance ohms, then repair.
between terminals 2, 5,
49 and 54 (circuits 34,
97-G, 34A, and 34) and all
other terminals in (400).
2. Off At (4001) measure (400), 34, >100K Go to Locate short to
resistance to ground 97-G, 34A, ohms. next ground in any
at terminals 2, 5, 49 and and 34 to gnd. step. circuit(s) where
54 (circuits 34, 97-G, 34A, resistance is less
and 34). than 100K ohms,
then repair.
3. On At (400) measure voltage (400), circuits <1.5 volts. Go to Locate short to
to ground at terminals 2, 34, 97-G, next unwanted voltage
5, 49 and 54 (circuits 34, 34A, and 34 step. source in any
97-G, 34A, and 34). to gnd. circuit(s) where
voltage is more than
1.5V, then repair.
4. Off Measure resistance of 34, 34A, <5 ohms Go to Locate open or
circuits 34, 34A, 97-G and 97-G, and next poor connection
34B between connectors 34B between step. in circuit(s) if
(400) and (402). (400) and resistance is more
(402) than 5 ohms, then
repair.
5. Off The low coolant switch
circuits check good.
If problem is still
present, replace low
coolant switch. If
problem persists, have
a Caterpillar dealer
diagnose ECM operation.

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210 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

3.13. ENGINE BRAKE CONTROLS

Testing Engine Brake Switches and Circuits

NOTE – Disconnecting (400) from the ECM will cause incremental amounts of Trip Data to be lost.
An “Event Recorder Data Lost” code may also be logged. The loss of this data will not affect engine
operation, but will affect the accuracy of the data. Ask the owner/operator if they want data recorded
before disconnecting.

Table 54 Testing Engine Brake Switches and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove conn. (434) Engine <2 ohms. Go to next Replace engine
from on/off switch. Use brake step. brake on/off
ohmmeter to test the switch, 5 to switch.
switch. In the on position, 6.
continuity should be
present between terminals
5 and 6.
2. Off Use ohmmeter to test the Engine >100K Go to next Replace engine
switch. In the off position, brake ohms. step. brake on/off
no continuity should be switch, 5 to switch.
present between terminals 6.
5 and 6.
3. Off Measure resistance (434), 24-G <5 ohms. Go to next Locate open or
between conn. (434) to gnd. step. poor connection
terminal 6 and ground. in circuit(s)
24-G, 97-GA,
97-G, between
connectors
(434) and (400),
then repair.
4. Off Remove conn. (433) from 24A <5 ohms. Go to next Locate open or
engine brake selector between step. poor connection
switch. Measure resistance (434) and in circuit
of circuit 24A between (433). 24A between
connectors (434) and connectors
(433). (434) and (433),
then repair.
5. Off Use ohmmeter to test Engine <2 ohms. Go to next Replace the
selector switch in position brake step. switch.
1, continuity between switch, 2 to
terminals 2 and 3. 3.
6. Off Use ohmmeter to test Engine <2 ohms. Go to next Replace the
selector switch in position brake step. switch.
2, continuity between switch, 2 to
terminals 2 and 6. 6.

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 211

Table 54 Testing Engine Brake Switches and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
7. Off Use ohmmeter to test Engine <2 ohms. Go to next Replace the
selector switch in position brake step. switch.
3, continuity between switch, 2,
terminals 2, 3 and 6. 3 and 6.
8. Off Remove connector (400), (433), 24AE <5 ohms. Go to next Locate open or
use test lead to jumper to ground. step. poor connection
terminal 40 (circuit 24AE) in circuit
to ground. At connector 24AE between
(433) measure resistance connectors
to ground at circuit 24AE. (433) and (400),
then repair.
9. Off At connector (400), install (433), 24AE <5 ohms. Go to next Locate open or
jumper between terminals to 24AF. step. poor connection
40 and 23 (circuits 24AE in circuit
and 24AF). At (433) 24AF between
measure resistance connectors
between circuits 24AE (433) and (400),
and 24AF. then repair.
10. Off Remove jumper from (433), 24A, >100K Go to next Locate short to
connector (400), but do 24AE and ohms. step. ground, then
not reconnect (400) yet. 24AF to repair.
With on/off switch off, at ground.
connector (433) measure
resistance to gnd. at
circuits 24A, 24AE and
24AF.
11. Off At connector (433) measure (433) >100K The cruise Locate short
resistance between circuits between ohms. control between
24A, 24AE and 24AF. 24A, 24AE switches circuits, then
and 24AF. and circuits repair.
check
good.

Testing J1922 Circuits

Table 55 Testing J1922 Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove ECM conn. (400) (400) >100K Go to Locate short between
and J1922 conn. (403). between ohms. next circuits, then repair.
Measure resistance 97Y(-) and step.
between circuits 98Y(-) 98Z(+).
and 98Z(+).

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212 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

Table 55 Testing J1922 Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off At conn. (400), install (403), 98Y(-) <5 Go to Locate open or poor
jumper between terminals and 98Z(+). ohms. next connection in circuits
1 and 14. Measure step 98Y(-) and 98Z(+),
resistance between conn. between connectors
(403), circuits 98Y(-) and (403) and (400), then
98Z(+). repair.
3. Off With jumper still in place, Between >100K Go to Locate short between
at conn. (403) measure (403) and ohms. next (403) circuits and
resistance between ground. step. ground, then repair.
circuits 98Y(-) and 98Z(+)
to ground.
4. Off J1922 circuits check
good. Remove jumper,
reconnect (403) and
(400).

4. COMPONENT LOCATIONS
(1) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Left Side of Engine Cowl
(2) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Right Side of Engine Cowl, Above Conn. 3
(3) Dash Panel Connector.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . Right Side of Engine Cowl, Below Conn. 2
(94) Back-Up Light Switch.. . .. .. . .. . .. .. . .. .. . .. .. . ... . . . . . On Transmission
(137) 6–Way Data Link Connector. . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(141) Ser. Brake Switch/Cruise Switch. . . . . . . . . . . . .. . . . . . Dash Panel, Left Side, Engine Side.
(190) Cab Overlay to Engine Harness. . . . . . . . . . . . . .. . . . . . Right Instrument Panel
(217) Inline Fuse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Near ECM
(218) Inline Fuse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Near ECM
(227) Fan Solenoid. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . ... . . . . . At Front of Engine
(228) Refrigerant Pressure Switch. . . . . . . . . . . . . . . . . .. . . . . . On A/C Compressor
(229) Engine Oil Temp Sender. . .. . .. .. . .. . .. . .. .. . ... . . . . . Left Side of Engine
(275) Thermal Overcrank Protection. . . . . . . . . . . . . . . .. . . . . . At the Cranking Motor
(294) Clutch Switch Connector. . . . . . . . . . . . . . . . . . . . . .. . . . . . Near Clutch Switch
(400) OEM Interface Connector. . . . . . . . . . . . . . . . . . . . .. . . . . . On Engine
(402) Low Coolant Level.. .. .. .. .. .. .. .. .. .. .. .. .. .. ... . . . . . In Instrument Panel to Left of Tachometer
(403) J1922 Data Link. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Dash Panel Right Side
(404) Throttle Position Sensor. . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Left Instrument Panel
(409) Vehicle Speed Sensor. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . On Transmission to Engine Harness
(420) Right Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Gauge Cluster
(421) Speedo./Tach. Module. . . .. . . .. . .. . . .. . . .. . . .. .. . . . . . Behind Speedo./Tach. Gauge
(422) Speedo./Tach. Module. . . .. . . .. . .. . . .. . . .. . . .. .. . . . . . Behind Speedo./Tach. Gauge
(423) Left Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Left Gauge Cluster
(424) Left Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Left Gauge Cluster
(514) Data Link — Positive.. . . .. . . .. . . .. . . .. . . .. . . .. .. . . . . . Behind Instrument Panel/Behind Cluster
(515) Data Link — Negative.. .. .. .. . .. .. .. .. . .. .. .. ... . . . . . Behind Instrument Panel/Behind Cluster
(640) Stop Light Switch. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . .. . . . . . Dash Panel, Left Side Engine Compartment

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 213

Figure 80 Engine Wiring, Cab Effects

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214 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

1. DASH PANEL (VIEWED FROM INSIDE ENGINE COMPARTMENT

2. (141) BRAKE SWITCH
3. (640) STOP LIGHT SWITCH
4. (190) ELECTRONIC ENGINE CONNECTOR
5. RIGHT HAND DASH PANEL GROUND STUD
6. (3) ENGINE CONNECTOR
7. (2) CHASSIS HARNESS CONNECTOR
8. POWER DISTRIBUTION PANEL
9. RUN RELAY
10. SWITCHES
11. RIGHT GAUGE CLUSTER
12. SPEEDOMETER/TACHOMETER CLUSTER
13. LEFT GAUGE CLUSTER
14. (514) DATA LINK CONNECTOR
15. (515) DATA LINK CONNECTOR
16. (137) DATA LINK
17. FRONT END HARNESS CONNECTOR
18. THROTTLE PEDAL
19. (267) THROTTLE PEDAL CONNECTOR
20. CLUTCH SWITCH
21. (294) CLUTCH SWITCH CONNECTOR

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 215

Figure 81 Engine Wiring at Dash Panel

1. (190) ELECTRONIC ENGINE CONNECTOR
2. RH DASH PANEL GROUND STUD
3. (3) CHASSIS HARNESS CONNECTOR
4. (2) CAB/ENGINE HARNESS CONNECTOR
5. CIRCUIT 17D USED WITH THERMAL OVERCRANK SYSTEM
6. START MAGNETIC SWITCH
7. CIRCUIT 17C
8. CIRCUIT 17B
9. CIRCUIT 14
10. CIRCUIT 14A TO (B1) BATTERY STUD
11. (402) LOW COOLANT LEVEL SWITCH
12. ENGINE HARNESS

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216 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

Figure 82 Engine Wiring, C–10 & C–12

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 217

1. GROUND STUD
2. CIRCUIT 11–GR, RADIATOR GROUND
3. (228) A/C PRESSURE SWITCH CONNECTOR
4. TO ENGINE WIRING AT DASH PANEL
5. (1097) BACKBONE FOR J1939
6. ETHER THERMOCOUPLE CIRCUIT 21A
7. J1922 DATALINK CONNECTOR
8. (1098) TERMINATION RESISTOR FOR J1939
9. TRANSMISSION TEMPERATURE GAUGE CONNECTOR
10. (229) ENGINE OIL TEMPERATURE GAUGE CONNECTOR
11. (275) THERMAL OVERCRANK CONNECTOR
12. (400) INTERNATIONAL ECM CONNECTOR
13. CIRCUIT 17C
14. CIRCUIT 97/97A
15. FUSIBLE LINK
16. CIRCUIT 11–GS
17. CIRCUIT 2–G

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218 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

Figure 83 Engine Wiring, C–10 and C–12

1. CIRCUITS 2 and 2G
2. TO ENGINE WIRING AT DASH PANEL
3. CIRCUIT 77C TO A/C COMPRESSOR CLUTCH (228)

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 219

Figure 84 Engine Wiring, C–10 and C–12

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220 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

1. CIRCUIT 2
2. CIRCUIT 14
3. CIRCUIT A2
4. CIRCUIT 2-G
5. CIRCUIT 2-G
6. CIRCUIT 2
7. CIRCUIT 14
8. CIRCUIT 2-G
9. CIRCUIT 2
10. CIRCUIT 14
11. CIRCUIT 14
12. CIRCUIT 2
13. CIRCUIT 2-G

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 221

Figure 85 Engine Wiring, 3406E

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222 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

1. FRAME GROUND STRAP

2. CIRCUITS 30 & 30–GA ENGINE OIL TEMP.
3. CIRCUITS 17D & 17–G THERMAL OVERCRANK
4. TO OTHER SIDE OF ENGINE
5. TO ENGINE WIRING AT DASH PANEL
6. J1922 CONTROL DATA LINK CONNECTOR
7. (1097) J1939 BACKBONE
8. (1098) J1939 TERM. RESISTOR
9. TO TRANSMISSION
10. CIRCUIT 21 ETHER START
11. (400) NAVISTAR ECM CONNECTOR
12. GROUND STUD
13. CIRCUIT 17C
14. FUSIBLE LINK
15. CIRCUIT 97/97A
16. CIRCUIT 11-GS
17. CIRCUIT 2-G

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 223

Figure 86 Engine Wiring, 3406E

1. GENERATOR
2. TO OTHER SIDE OF ENGINE
3. FAN SOLENOID AIR HOSE

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224 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

Figure 87 Engine Wiring, 3406E

1. CIRCUIT 14
2. CIRCUIT 2
3. CIRCUIT 2-G
4. CIRCUIT 2 and 14

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 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES 225

Figure 88 Engine Wiring, Transmission Effects

1. TO ENGINE HARNESS
2. BACKUP LIGHT SWITCH (94) CIRCUITS 71 and 71A
3. VEHICLE SPEED SENSOR

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226 6 CATERPILLAR C-10, C-12 AND 3406E ENGINES

s08210
 7 DETROIT DIESEL SERIES 60 ENGINES 227

Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .229

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .229
2.1. ECM POWER CIRCUITS.. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .230
2.2. SHUTDOWN OVERRIDE/DIAGNOSTIC SWITCH. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .230
2.3. ATA DATA LINK CONNECTOR. . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .230
2.4. IDLE SHUTDOWN FEATURE. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .231
2.5. COOLANT LEVEL PROBE. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . .231
2.6. ELECTRONIC ACCELERATOR PEDAL ASSEMBLY. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .231
2.7. CRUISE CONTROL. .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .232
2.8. VEHICLE SPEED SENSOR (VSS). .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .232
2.9. CLUTCH SWITCH.. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .232
2.10. SERVICE BRAKE SWITCH. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .232
2.11. IDLE TIMER/PARK BRAKE SWITCH.. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .233
2.12. ENGINE BRAKE. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. .233
2.13. ANTILOCK BRAKE INTERFACE. . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .233

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .233
3.1. DETERMINING FAULT CODES.. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .234
Diagnostic OnOff/Shutdown Override Switch. . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . .234
EZ-Tech and PRO-LINK 9000 Electronic Service Tools (EST).. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .235
3.2. INSPECTION.. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .235
Before Troubleshooting. .. . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . .235
Testing Relays. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .235
3.3. ACCELERATOR PEDAL (TPS/IVS). . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .236
Testing Throttle Position Sensor (TPS). . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .236
Testing Idle Validation Switch (IVS).. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .237
Testing Accelerator Pedal (TPS/IVS) Circuits. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .238
3.4. DIAGNOSTIC CONNECTOR (137) AND DATA LINK CIRCUITS INCLUDING
SPEEDOMETER/TACHOMETER INPUT CIRCUITS.. .. . .. .. . .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .240
Testing Diagnostic Connector Power and Ground Circuits. . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .240
Testing ATA Data Link Circuits.. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .240
3.5. CRUISE/PTO CONTROL SYSTEM AND RELATED COMPONENTS.. . . .. . .. . . .. . .. . . .. . .. . . .. . .242
Testing Clutch Switch.. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .242
Testing Service Brake Switch And Circuits.. . . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .243
Testing Cruise On/Off Switch. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .244
Testing Cruise Set/Resume Switch And Circuits. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .245
3.6. VEHICLE SPEED SENSOR (VSS). .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .247
Inspecting And Adjusting the Adjustable Vehicle Speed Sensor (VSS). . . . . . . . . . . . . . . . . .247
Testing Vehicle Speed Sensor (VSS).. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .247
Testing Vehicle Speed Sensor (VSS) Circuits To ECM. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . .248
3.7. ENGINE BRAKE SYSTEM.. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .249
Testing Engine Brake Switches and Circuits. . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .249
3.8. DIAGNOSTIC ON/OFF/SHUTDOWN OVERRIDE SWITCH (260). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251
Testing Diagnostic On/Off/Shutdown Override Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251
3.9. PARK BRAKE (IDLE TIMER) SWITCH (268). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .252
Testing Park Brake Switch (268) and Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .252

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228 7 DETROIT DIESEL SERIES 60 ENGINES

3.10. TESTING LOW COOLANT SENSOR CIRCUITS. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. ..253

3.11. ECM POWER SUPPLY (SWITCHED AND UNSWITCHED). . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ..254
Testing Unswitched Battery Power To ECM At Connector (676). . . . . . . . . . . . . . . . . . . . . . . . . . .254
Testing Switched Battery Power To ECM.. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . ..255

4. COMPONENT LOCATIONS. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . ..255

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 7 DETROIT DIESEL SERIES 60 ENGINES 229

1. DESCRIPTION
The Detroit Diesel Electronic Control system (DDEC III) provides an electronic fuel control system, electronic
engine protection and other operational controls.

DDEC III is standard on Series 60 engines and provides many engine/vehicle functions including:

• Cruise/PTO Controls
• Automatic Idle Shutdown Timer (3–100 Minutes)
• Engine Diagnostics
• Engine Protection System
• Engine Cooling System
• Engine Brake Control
• Speedometer/Tachometer Input Signals
• ABS/Traction Control Interface

Refer to Detroit Diesel manual furnished with the vehicle for additional feature information.

Since each Series 60 DDEC III system is electronically programmable to individual owner specifications, the
operating parameters will vary from vehicle to vehicle. These parameters include: maximum cruise speed,
maximum road speed settings and many others.

The “brain” of the DDEC III system is the Electronic Control Module (ECM), located on the left side of the
engine. The ECM receives inputs from the following International components:

• Vehicle Speed Sensor (VSS)

• Throttle Position Sensor (TPS)
• Service Brake Switch
• Park Brake Switch
• Clutch Switch
• Low Coolant Level Sensor
• Cab Switches

The ECM receives inputs from sensors and switches, then outputs signals to the injectors, engine brake relay
and other system components.

2. OPERATION
The ECM is connected to the International electrical system at two points (or three points with antilock
brakes installed).

A. International engine harness 30–way ECM connector (273) connects to ECM. This connector links
the International switches, sensors and data links and supplies ignition power to the ECM.
B. ECM power cable connector (676) supplies unswitched battery power and a ground path to
the ECM.

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230 7 DETROIT DIESEL SERIES 60 ENGINES

C. Additionally, with ABS/traction control system, the International 2–way J1922 data link connector
(403) connects the circuits to ECM communications connector (1160) and is used to provide
communications between the ECM and the ABS/traction control system controller.

Refer to the DETROIT SERIES 60 – ENGINE SYSTEMS circuit diagrams in CTS-5298 or S08225.

2.1. ECM POWER CIRCUITS

Power is supplied at all times from the positive battery terminal to the ECM over two circuits. The first circuit
consists of circuit 14A from the battery positive terminal, a 15A fuse, circuit 14D, connector (675), and circuit
14D to the ECM power connector (676). The second circuit consists of circuit 14B from the battery positive
terminal, a 15A fuse, circuit 14C, connector (675), and circuit 14C to the ECM power connector (676).

The ECM is grounded through circuits 11–GA, 11–GB, and 11–GC to a splice. From the splice the circuits are
grounded through circuit 11–G, connector (N/L) and circuit 11–G to the negative battery cable.

When the key switch is in the ignition or start position, power is applied to circuit 13Z, 5A fuse F6–D, circuit
13D, connector (2), and circuit 13D to the ECM (273).

2.2. SHUTDOWN OVERRIDE/DIAGNOSTIC SWITCH

The lighted two-position momentary engine shutdown override/diagnostic switch (260) is a dual function
switch. The switch overrides the engine shutdown and enables the on-board diagnostics.

The switch is connected to the negative battery terminal by way of circuits 97–GD and 97–GA, connector
(190), circuits 97–GA and 97–G, connector (N/L), circuits 97–G and 11–G, connector (N/L) and circuit 11–G to
the negative battery terminal. The switch is connected to the ECM by way of circuit 97AU, connector (190), and
circuit 97AU to ECM (273). Closing the switch causes the voltage state of circuit 97AU to change to ground,
indicating to the ECM that the switch has been toggled to the on position. Thus the ECM will switch modes to
display fault codes or the absence of codes by flashing the engine warning light and the stop engine light. The
red stop engine light will flash the active codes and the yellow engine warning light will flash the inactive codes.

2.3. ATA DATA LINK CONNECTOR

The six pin ATA data link connector (137) allows an electronic service tool (EST) to communicate with the
ECM. The data link carries serial data transmissions between the ECM and the electronic service tool and
between the ECM and the speedo/tachometer and the EST.

The ATA data link connector (137), which is located on the left instrument panel, has circuits in four of the
six cavities. The data link circuits are a twisted wire pair because twisting the wires helps shield them from
interference. The circuits are as follows:

A. Circuit 98A(+) is the positive data link connection and it is fed by the positive data link connector
(514), the jumper bus bar, circuit 98(+), connector (190), and circuit 98(+) coming from the ECM
connector (273).
B. Circuit 98C(-) is the negative data link connection and it is fed by the negative data link connector
(515), the jumper bus bar, circuit 98B(-), connector (190), and circuit 98B(-) coming from the
ECM connector (273).
C. Circuit 97D is a 12 volt circuit and is fed from B1 Battery Stud to circuit 14W and 14AA, through
20A fuse F5–D. Thus it provides power for the electrical service tool.

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 7 DETROIT DIESEL SERIES 60 ENGINES 231

D. Circuits 97–GR and 11–GT are connected to the panel lights ground adapter (506), and provide a
ground for the electronic service tool.

2.4. IDLE SHUTDOWN FEATURE

The customer selectable idle shutdown feature shuts down the engine (does not shut down power to the cab)
after a customer selected (programmed) length of time between 3 and 100 minutes. The timer (an ECM
function) begins counting when the parking brake is set (which closes the park brake switch [268]), the
engine temperature is above 104°F/40°C, the engine speed is at idle rpm, and the ECM does not see any
clutch or brake pedal operation.

If these conditions are present, the ECM counts down the customer selected length of time until 90 seconds
before the scheduled engine shutdown is to occur. At this time the yellow engine warning light begins to flash
rapidly. The idle timer can be disabled by depressing the accelerator pedal. This will allow the idle timer to be
overridden if longer idle time is wanted. The shutdown timing sequence can be re-started by releasing and
re-applying the parking brake.

If the idle timer shuts the engine down, fueling is stopped, but ignition voltage is still present to the ECM on
circuit 13D at connector (273).

NOTE – The key switch must be cycled to off and back to on before the engine will start.

NOTE – The engine is shut down, but power to the cab is not turned off.

2.5. COOLANT LEVEL PROBE

The low coolant level probe is connected through the Navistar engine harness connector (278) circuit 34 to
ECM (273). A signal from the ECM is sent to the probe on this circuit. The other side of the probe is connected
to ground through circuits 34–G, 97–G, connector (N/L), circuits 97–G and 11–G, connector (N/L), and circuit
11–G to battery ground. When coolant level is below the probe, the circuit resistance changes, indicating to the
ECM that the coolant level is below the critical level.

2.6. ELECTRONIC ACCELERATOR PEDAL ASSEMBLY

DDEC engines use an electronic accelerator pedal assembly that includes a throttle position sensor (TPS)
and idle validation switch (IVS) function. The TPS/IVS sensor assembly is not serviceable and if defective
must be replaced.

The TPS acts like a potentiometer. Movement of the pedal results in a variable signal being sent to the ECM.
This signal is proportional to the pedal position. A five volt signal from the ECM (273) is sent through circuit
99A, connector (190), and circuit 99A to the potentiometer of TPS/IVS (267). The variable potentiometer wiper
signal (varies with pedal position) is returned from the TPS/IVS (267) over circuit 99, connector (190), and
circuit 99 to the ECM (273). The TPS/IVS (267) potentiometer is grounded through circuit 99–R, connector
(190) and circuit 99–R to the ECM (273).

The IVS is used to verify when the accelerator pedal is in the idle position. One side of the idle validation
switch (273) is connected to circuit 99B, connector (190), and circuit 99B to the ECM (273). The ECM sets
this input at 5 volts and when the throttle is at idle a ground is applied to this input by the idle validation
switch (267). This ground pulls the input voltage down to nearly zero, telling the ECM that the accelerator
pedal is in the idle position. The ground path that is applied by the IVS (267) is through circuits 99–GA and
97–GA, connector (190), circuits 97–GA and 97–G, connector (N/L), circuit 97G and 11–G, connector (N/L),
and circuit 11–G to the negative battery terminal.

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The ECM analyzes the signals received from the TPS/IVS, making certain that the signals fall within certain
parameters. For example, if the IVS signal indicates that the pedal is in the idle position, the ECM expects to
see a TPS signal that indicates no throttle (or very little) is being applied. If the ECM does not see a logical
response from both, a fault code will be logged. The TPS/IVS timing cannot be checked using a multimeter.

2.7. CRUISE CONTROL

The cruise control operates when vehicle speed is greater than 20 mph and engine speed is greater than 1100
rpm. The vehicle speed signal used by the ECM to control the cruise system comes from the International
installed vehicle speed sensor. The PTO mode is activated when vehicle speed is zero and the park brake is
set (park brake switch [268] contacts open). Releasing the park brake disables the PTO controls.

The cruise control and PTO systems share the same components, which include a cruise on/off switch (435),
cruise set/resume switch (436), service brake switch (141), park brake switch (268), clutch pedal switch
(294) and vehicle speed sensor (250).

The lighted cruise on/off switch (435) is connected by circuit 97AE, connector (190), and circuit 97AE to the
ECM (273). The other side of switch (435) is connected through circuits 97–GC, 97–GB, 97–GA, connector
(190), circuits 97–GA and 97–G, connector (N/L), circuits 97–G and 11–G, connector (N/L), and circuit 11–G to
negative battery stud. With the switch in the on position, the voltage state at the ECM input changes to ground,
telling the ECM that the switch is in the on position.

The lighted set/resume switch (436) is connected by circuit 97AB, connector (190), and circuit 97AB to the
ECM (273). The switch is also connected by circuit 97AA, connector (190) and circuit 97AA to the ECM (273).
The switch (436) is connected to the panel lights ground adapter (506) by way of circuits 62–GK and 11–GP.

With the switch held in the set position, circuit 97AB is switched to ground signaling the ECM (273). With the
switch held in the resume position, circuit 97AA is switched to ground, signaling the ECM (273).

2.8. VEHICLE SPEED SENSOR (VSS)

The vehicle speed sensor (250) feeds a VSS signal to the ECM (273) by way of circuits 97AJ and 97AK.

Two types of sensors may be used. The threaded (adjustable sensor is used on most transmissions. A new
push-in sensor (non-adjustable) is used on some transmissions.

2.9. CLUTCH SWITCH

The clutch switch (294) is a normally open (N.O.) switch that is adjusted so that its contacts are closed when
the clutch pedal is in the released position. Depressing the clutch pedal causes the switch contacts to open.

The clutch switch is connected by circuit 97AH, connector (190), and circuit 97AH to the ECM (273). The other
side of the switch is connected through circuits 97–GH, 97–GA, connector (190), circuit 97–GA and 97–G,
connector (N/L), circuits 97–G and 11–G, connector (N/L), and circuit 11–G to negative battery stud.

2.10. SERVICE BRAKE SWITCH

The service brake switch (141) is a normally closed (N.C.) air operated switch. Its contacts are closed when
the brakes are not applied and its contacts open up when the brakes are applied. One terminal of the service
brake switch (141) is connected to circuit 97AL, connector (190), circuit 97AL and the ECM (273). The other
terminal of the switch is connected to ground by way of circuit 97–GF and 97–GA, connector (190), circuits
97–GA and 97–G, connector (N/L), circuits 97–G and 11–G, connector (N/L), and circuit 11–G to the negative
terminal of the batteries.

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 7 DETROIT DIESEL SERIES 60 ENGINES 233

2.11. IDLE TIMER/PARK BRAKE SWITCH

The idle timer/park brake switch (268) is an air operated normally closed (N.C.) switch. Its contacts are
closed when the parking brakes are applied, and its contacts open up when the brakes are released. One
terminal of the idle timer switch (268) is connected to circuit 97AV, connector (190), circuit 97AV and the
ECM (273). The other terminal of the switch is connected to ground by way of circuits 97–GE and 97–GA,
connector (190), circuits 97–GA and 97–G, connector (N/L), circuits 97–G and 11–G, connector (N/L), and
circuit 11–G to the negative terminal of the batteries.

2.12. ENGINE BRAKE

The driver controls the engine brake on/off and selector switches but the ECM enables or disables the system
by way of a relay in response to the engine throttle position. The ECM enables the relay whenever the engine
speed is 150 rpm greater than idle rpm, and the throttle is in the idle position.

The engine brake can provide braking when the vehicle is in the cruise control mode. For example, if the
vehicle is in the cruise control mode, going down hill, and the engine brake is selected, the ECM will control the
engine brake with respect to the cruise control set speed. The amount of braking will not exceed the number
of cylinders selected at the brake selector switch.

The lighted two position engine brake on/off switch (434) receives a ground signal on circuits 24–GA and
97–GA, connector (262), circuits 97–GA and 97–G, connector (N/L), circuits 97–G and 11–G, connector (N/L),
and circuit 11–G to the negative terminal of the batteries. In the on position a ground signal is sent from the
switch on circuit 24AJ to the engine brake selector switch (433).

When switch (433) is placed in the first position, a ground is applied to circuit 24AE, connector (190) and circuit
24AE to the ECM (273). This tells the ECM to enable the brake solenoid for two of the cylinders.

When switch (433) is placed in the second position, a ground is applied to circuit 24AF, connector (190) and
circuit 24AF to the ECM (273). This tells the ECM to enable the brake solenoids for four of the cylinders.

When switch (433) is placed in the third position, a ground is applied to circuit 24AE, connector (190) and
circuit 24AE to the ECM (273) and circuit 24AF, connector (190), and circuit 24AF to the ECM (273). This
tells the ECM to enable the brake solenoids for all six of the cylinders.

2.13. ANTILOCK BRAKE INTERFACE

If the vehicle is equipped with antilock brakes, information is shared with ABS controller module (766) over
a pink wire, connector (403), and circuit 98Z(+) to the ECM (1160). Information is also shared by the ABS
module (766) over a light blue wire, connector (403) and circuit 98Y(-) to the ECM (1160).

3. TROUBLESHOOTING
Refer to the DETROIT SERIES 60 – ENGINE SYSTEMS circuit diagrams in CTS-5298 or S08225.

A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.

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234 7 DETROIT DIESEL SERIES 60 ENGINES

C. Before beginning these test procedures, inspect all connectors for loose or damaged pins, wires,
etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in the GROUP 08 —
ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit, by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the position are generally not covered
in detail. It is assumed that the technician knows to check for a malfunctioning switch, relay, or
solenoid.

3.1. DETERMINING FAULT CODES

The ECM continuously monitors itself and other system components, including sensors, injectors, connectors
and associated wiring.

The yellow Engine Warning Light is turned on if a minor fault occurs. A fault code is also logged. This
indicates the problem should be diagnosed as soon as possible.

The ECM turns on the yellow Engine Warning Light and the red Stop Engine Light and stores a fault code
if a major fault is detected. If this occurs, the vehicle should be brought to a safe stop and the engine shut down.

A diagnostic check may be performed using the diagnostic on/off switch, the EZ-Tech or Pro-Link 9000 EST.

Diagnostic OnOff/Shutdown Override Switch

The diagnostic on/off switch is used to signal the ECM to flash the yellow Engine Warning light and the red
Stop Engine light to flash codes. The red Stop Engine light will flash the ACTIVE codes and the yellow
Engine Warning light will flash the INACTIVE codes.

If no fault codes are logged, the code "25" will be flashed out on the yellow Engine Warning Light. For example,
the yellow Engine Warning light blinks out: FLASH, FLASH. The first digit is a 2, then a half-second pause:
FLASH, FLASH, FLASH, FLASH, FLASH. The second digit is a 5. Code 25 is System OK.

The diagnostic on/off switch is used to flash codes in the following circumstances:

A. When the engine is not running and the ignition switch is on, toggling and releasing the diagnostic
on/off switch will flash out the engine codes. Toggling then releasing the diagnostic on/off switch a
second time will stop the ECM from flashing the codes.
B. When the engine is idling and not in an "engine protection condition," toggling and releasing the
diagnostic on/off switch will flash out the engine codes. Toggling then releasing the diagnostic
on/off switch a second time will stop the ECM from flashing the codes.

NOTE – All Series 60 fault codes are 2 digits.

The Detroit Diesel Troubleshooting Manual contains flash code descriptions and diagnostic procedures.

If the fault code(s) or symptoms indicate a need to troubleshoot an International installed circuit or component,
procedures are included in this chapter or other CTS-5000 Master Service Manual sections.

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 7 DETROIT DIESEL SERIES 60 ENGINES 235

EZ-Tech and PRO-LINK 9000 Electronic Service Tools (EST)

The EZ-Tech or the PRO-LINK 9000 electronic service tools (EST) with a Series 60 program can be used to
read logged fault codes and monitor many of the system switches and operating parameters. Refer to the
EZ-Tech and PRO-LINK 9000 manuals for information on using the EST.

International vehicles include an 6-way diagnostic connector used to access the system with an EST.

The diagnostic tables in this section are not designed for specific symptoms, but designed to test those circuits
and components installed by International. Use DDEC III diagnostics procedures to identify the suspect circuit
or system, then use the procedures included in this section to troubleshoot the specific International circuit.

3.2. INSPECTION
NO TESTS in this section require testing "into" the DDEC ECM.

Before Troubleshooting

A. Before troubleshooting, make sure that the vehicle batteries are fully charged!Check battery
cables and grounds for clean, tight connections free of damage and corrosion. Many of the voltage
tests included in the procedures will give misleading readings if the batteries are not fully charged.
B. Before troubleshooting a particular circuit, inspect connectors for pushed back, loose or damaged
(spread or bent), or corroded terminals, or wires with cut strands, etc. The wires and connections
must be free of damage or corrosion. When some connectors corrode, a light white residue will
be present that must be removed.
C. Before troubleshooting, inspect the suspect circuit grounds for clean, tight connections free of
damage or corrosion.

Testing Relays

International circuits use suppressed relays for controlling power to load devices (Figure 69). The suppression
feature (a resistor circuit parallel to the relay coil) prevents voltage spikes from damaging electronic
components in the vehicle. These relays must be replaced with approved International parts.

Figure 89 Typical Relay

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236 7 DETROIT DIESEL SERIES 60 ENGINES

The part number and relay circuit diagram are embossed on the relay body. The terminals are numbered on
the relay in the same manner as in the circuit diagrams.

Relay Test Procedure

1. With relay removed, measure resistance between terminals 30 and 87A. If resistance is less than 5
ohms, go to step 2; otherwise replace the relay.

2. Measure resistance between terminals 30 and 87. If resistance is 100K ohms or more, go to step 3;
otherwise replace the relay.

3. Using 12V battery source and test leads, connect (+) lead to terminal 85 and (-) lead to terminal 86. If relay
energizes with an audible click sound, go to step 4; otherwise replace the relay.

4. While relay is energized, measure resistance between terminals 30 and 87. If resistance is less than 5
ohms, go to step 5; otherwise replace the relay.

5. While relay is energized, measure resistance between terminals 30 and 87A. If resistance is 100K ohms or
more, the relay is good; otherwise replace relay.

Refer to the appropriate circuit diagrams in CTS-5298 or S08225.

3.3. ACCELERATOR PEDAL (TPS/IVS)

Inspect the TPS circuits and connectors as outlined in Before Troubleshooting. The following 3 tests, Testing
Throttle Position Sensor (TPS)), Testing Idle Validation Switch (IVS) and Testing Accelerator Pedal (TPS/IVS)
Circuits, check the TPS/IVS connection and related International cab and engine harness connections leading
to the ECM.

These tests should be performed if a DDEC III fault code indicates a problem in the circuits or if the EZ-Tech or
PRO-LINK 9000 indicates that the TPS/IVS is not working properly while monitoring switches.

NOTE – The following 3 tests must be performed in sequence.

Testing Throttle Position Sensor (TPS)

This test checks the TPS circuits in the accelerator pedal assembly. This test will identify if the resistance of
the pedal circuits is within specifications.

Table 56 Testing Throttle Position Sensor (TPS)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect the At 2000 to Go to next Replace TPS/IVS
accelerator pedal from accelerator 3000 step. sensor.
cab harness connector pedal A ohms.
(267). At the pedal side of to C.
(267) measure resistance
between terminals A and
C with the pedal in the
idle position, then with
the pedal fully depressed.
Resistance should be

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 7 DETROIT DIESEL SERIES 60 ENGINES 237

Table 56 Testing Throttle Position Sensor (TPS) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2000 to 3000 ohms in all
positions.
2. Off With the pedal at idle, at At 1500 to Go to next Replace TPS/IVS
connector (267) measure accelerator 3000 step. sensor.
resistance between pedal B ohms.
terminals B and C. to C.
3. Off With pedal at full throttle At 250 to Go to next Replace TPS/IVS
position, at connector accelerator 1500 step. sensor.
(267) measure resistance pedal B ohms,
between terminals B and to C. and 1000
C. Resistance must be less
1000 ohms less than than idle
reading at idle position position
and must be 250 to 1500 reading.
ohms.
4. Off At accelerator pedal Accelerator >100K APS Replace APS/IVS
and connector (267), pedal ohms. sensor sensor.
measure resistance to metal to checks
the metal part of pedal terminals. good. Go
assembly and terminals to Testing
A, B, C, D and E. Idle
Validation
Switch
(IVS).

Testing Idle Validation Switch (IVS)

Perform preceding test before performing this test. This test checks the IVS circuits in the accelerator
pedal assembly.

Table 57 Testing Idle Validation Switch (IVS)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With accelerator pedal At <125 Go to next Replace TPS/IVS
still disconnected at accelerator ohms. step. sensor.
connector (267) and the pedal F to
pedal at idle, measure E.
resistance between
terminal F and E on the
accelerator pedal.

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238 7 DETROIT DIESEL SERIES 60 ENGINES

Table 57 Testing Idle Validation Switch (IVS) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off At connector (267), At >100K Go to next Replace TPS/IVS
measure resistance accelerator ohms. step. sensor.
between terminals E pedal E to
and F while slowly F after 10°
depressing the pedal of travel.
(idle to full throttle). After
approximately 10° of
travel the resistance
should be 100K ohms or
more.
3. Off The TPS and IVS Go to
functions check good. Testing
NOTE: This test is not Accelerator
able to check the timing Pedal
function between the (TPS/IVS)
two functions. Circuits
following.

Testing Accelerator Pedal (TPS/IVS) Circuits

Inspect TPS/IVS circuits and connectors as outlined in Before Troubleshooting. This test checks the cab and
engine harness TPS/IVS circuits for opens, shorts to ground, shorts to "hot" circuits and shorts to other circuits
in the harness and checks the circuits for continuity.

Perform the two preceding tests before performing this test.

Table 58 Testing Accelerator Pedal (TPS/IVS) Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With accelerator pedal (273), >100K Go to next Locate short to
disconnected from the 99B, 99R, ohms. step. ground, then repair.
cab harness at (267), 99 and
disconnect connector 99A to
(273) from the ECM. gnd.
At International ECM
connector (273), measure
resistance to gnd. at
terminals E1, C3, D2 and
A3 (circuits 99B, 99R, 99
and 99A).
2. Off At harness and connector (273), >100K Go to next Locate short between
(273) measure resistance 99B, 99R, ohms. step. circuits, then repair.
between terminals E1, 99 and
C3, D2, A3 (99B, 99R, 99A to
99 and 99A) and all other all cir. in
terminals in connector conn.
(273).

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 7 DETROIT DIESEL SERIES 60 ENGINES 239

Table 58 Testing Accelerator Pedal (TPS/IVS) Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
3. Off At harness and connector (273), <1 volt. Go to next Locate short to
(273) measure voltage to 99B, 99R, step. unwanted voltage
ground at terminals E1, 99 and source, then repair.
C3, D2, A3 (circuits 99B, 99A to
99R, 99 and 99A). gnd.
4. Off At harness and connector (267), <5 ohms. Go to next Locate open or
(267) measure resistance 99-GA to step. poor connection in
to ground at terminal F gnd. gnd. path between
(circuit 99-GA). connector (267)
terminal F and
negative battery
terminal, then repair.
5. Off At connector (273) use (267), <5 ohms. Go to next Locate open or
test lead to jumper 99B to step. poor connection in
terminal E1 (circuit 99-GA. circuit 99B between
99B) to negative battery connectors (273) and
terminal. At connector (267), then repair.
(267) measure resistance
between terminals E
and F (circuit 99B and
99-GA).
6. Off At connector (273) use (267), <5 ohms. Go to next Locate open or
test lead to jumper 99R to step. poor connection in
terminal C3 (circuit 99-GA. circuit 99R between
99R) to negative battery connectors (273) and
terminal. At connector (267), then repair.
(267) measure resistance
between terminals A and
F (cir. 99R and 99-GA).
7. Off At connector (273) use (267), 99 <5 ohms. Go to next Locate open or
test lead to jumper to 99-GA. step. poor connection in
terminal D2 (cir. 99) circuit 99 between
to negative battery connectors (273) and
terminal. At connector (267), then repair.
(267) measure resistance
between terminals B and
F (cir. 99 and 99-GA).
8. Off At connector (273) use (267), <5 ohms. TPS/IVS Locate open or
test lead to jumper 99A to circuits poor connection in
terminal A3 (cir. 99A) 99-GA. between circuit 99A between
to gnd. At connector (273) and connectors (273) and
(267) measure resistance (267) (267), then repair.
between terminals C and check
F (cir. 99A and 99-GA). good.

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3.4. DIAGNOSTIC CONNECTOR (137) AND DATA LINK CIRCUITS INCLUDING

SPEEDOMETER/TACHOMETER INPUT CIRCUITS
Make sure batteries are fully charged and inspect circuits and connectors as outlined in Before Troubleshooting.

Testing Diagnostic Connector Power and Ground Circuits

This table checks the power and ground circuits to the diagnostic connector (137).

Table 59 Testing Diagnostic Connector Power and Ground Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove 5A fuse F9-C F9-C <1 ohm. Go to next Locate cause of
and check for open step. oveload condition,
condition. Fuse OK? then repair. Replace
fuse.
2. On Re-install fuse F9-C. At (137), 10 to 12 Go to next Locate cause of no or
diagnostic connection 97DLto volts. step. low voltage in circuit
(137) measure voltage gnd. 97DL from fuse, then
to ground at terminal C repair.
(circuit 97DL).
3. On At connector (137) (137), 10 to 12 Go to next Locate open or
measure voltage 97DL to volts. step. poor connection in
between terminals C 97-GR. ground circuit between
and E (circuits 97DL and connector (137) and
97-GR). (506) ground adapter,
then repair.
4. On The power and ground
circuits to diagnostic
connector (137) check
good. Proceed to
following table.

Testing ATA Data Link Circuits

This test checks the data link circuits between ECM connector (273) and the diagnostic connector (137)
and the speedometer/tachometer connector (421).

Table 60 Testing ATA Data Link Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect ECM Go to next
connector (273) step.
from ECM and (421)
from speedometer/
tachometer unit. If
any other devices are
connected to the data
link connectors (515) and

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Table 60 Testing ATA Data Link Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
(514) disconnect these
devices.
2. On At connector (137) (137), >100K Go to next Locate short to ground
measure resistance to 98A(+) to ohms. step. in circuit, then repair.
gnd. at terminal A, circuit gnd.
98A(+).
3. On At connector (137) (137), >100K Go to next Locate short to ground
measure resistance to 98C(-) to ohms. step. in circuit, then repair.
ground at terminal B, gnd.
circuit 98C(-).
4. On At connector (137) (137), >100K Go to next Locate short between
measure resistance 98A(+) to ohms. step. the positive data link
between terminals A and 98C(-). circuit and the negative
B, circuits 98A(+) and data link circuit, then
98C(-). repair.
5. On Measure voltage to (137), <1 volt. Go to next Locate short to
ground at connector 98A(+) to step. unwanted voltage
(137) terminals A, circuit gnd. and source, then repair.
98A(+) and B, circuit 98C(-) to
98C(-). gnd.
6. Off At ECM connector (273) (137), <5 ohms. Go to next Locate open or poor
use test lead to jumper 98C(-) to step. connection in circuit
terminal C1, circuit 98B(-) gnd. 98B(-) or 98C(-)
to gnd. At connector between connectors
(137) measure resistance (273) and (137), then
to ground at terminal B, repair.
circuit 98C(-).
7. Off At connector (421) (421), <5 ohms. Go to next Locate open or poor
measure resistance to 47/48(-) to step. connection in circuit
ground at circuit 47/48(-). gnd. 47/48(-) between
connectors (515) and
(421), then repair.
8. Off At ECM connector (273) (137), <5 ohms. Go to next Locate open or poor
use test lead to jumper 98A(+) to step. connection in circuit
terminal C1 to C2, circuit 98C(-). 98A(+) or 98(+)
98B(-) to 98(+). At between connectors
connector (137) measure (273) and (137), then
resistance between repair.
terminals A and B, circuit
98A(+) to 98C(-).

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Table 60 Testing ATA Data Link Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
9. Off At connector (421) (421), <5 ohms. Go to next Locate open or poor
measure resistance to 47/48(+) step. connection in circuit
ground at circuit 47/48(+). to gnd. 47/48(+) between
connectors (514) and
(421), then repair.
10. Off The data link circuits
between connectors
(273) and (137) and (421)
check good.

3.5. CRUISE/PTO CONTROL SYSTEM AND RELATED COMPONENTS

Inspect TPS/IVS circuits and connectors as outlined in Before Troubleshooting.

IMPORTANT – The following cruise control test procedures must be performed in the sequence that they
appear in this manual. Each test relies on information from the previous test procedure.

NOTE – The clutch switch is a normally open switch, adjusted to be closed when the pedal is in the
released (foot off) position.

NOTE – Use the EZ-Tech or PRO-LINK 9000 EST to check clutch switch operation. If the EST indicates
the clutch switch is not operating properly, perform this procedure.

Testing Clutch Switch

Table 61 Testing Clutch Switch

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Visually check clutch Go to next Adjust clutch switch.
switch adjustment. The step.
switch should be adjusted
to open with an audible
click when the pedal is
depressed 0.5 inch (13
mm). Is clutch switch
adjusted properly?
2. Off Disconnect clutch switch Clutch <5 ohms. Go to next If switch is properly
pigtail from cab harness switch, step. adjusted, replace the
at connector (294). With across switch.
pedal released, measure terminals.
resistance across pigtail
connector terminals.
3. Off Depress clutch pedal Clutch >100K Go to next If switch is properly
and measure resistance switch, ohms. step. adjusted, replace the
across pigtail connector across switch.
terminals. terminals.

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Table 61 Testing Clutch Switch (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off At cab side of connector (294), <5 ohms. Go to next Locate open or poor
(294), measure 97-GH to step. connection in gnd.
resistance of 97-GH gnd. path for circuit 97-GH
to gnd. between connector
(294) and negative
battery terminal, then
repair.
5. Off Disconnect ECM (294), <5 ohms. The clutch Locate open or
connector (273) from 97AH to switch and poor connection in
ECM. Use test lead to gnd. circuits circuit 97AH between
jumper terminal J2 , check connectors (273) and
(circuit 97AH) to ground. good. (294), then repair.
At connector (294)
measure resistance to
gnd. at circuit 97AH.

Testing Service Brake Switch And Circuits

Inspect circuits and connectors as outlined in Before Troubleshooting.

NOTE – Use the EZ-Tech or PRO-LINK 9000 EST to check service brake switch operation. If the EST
indicates the service brake switch is not operating properly, perform this procedure.

NOTE – Vehicle air brake system must be fully charged for this test.

Table 62 Testing Service Brake Switch And Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove harness Service >100K Go to next Replace service brake
connector (141) from brake ohms. step. switch.
service brake switch. switch,
Measure resistance to terminals
ground at both service to gnd.
brake switch terminals.
2. Off At service brake switch, Service <2 ohms. Go to next Replace service brake
measure resistance brake step. switch.
between the two switch,
terminals with brakes across
released. terminals.
3. Off At service brake switch, Service >100K Go to next Replace service brake
measure resistance brake ohms. step. switch.
between the two switch,
terminals with brakes across
applied. terminals.

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Table 62 Testing Service Brake Switch And Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off At service brake switch (141), <5 ohms. Go to next Locate open or poor
harness connector (141), 97-GF to step. connection in gnd.
measure resistance to gnd. path for circuit 97-GF
gnd. at circuit 97-GF. between connector
(141) and negative
battery terminal, then
repair.
5. Off Remove ECM connector (273), >100K Go to next Locate short to gnd. in
(273) from the ECM. At 97AL to ohms. step. circuit 97AL between
connector (273) measure gnd. connectors (273) and
resistance to gnd. at (141) then repair.
terminal G2, (circuit
97AL).
6. Off Use test lead to jumper (141), <5 ohms. The Locate open or
terminal G2 to gnd. At 97AL to service poor connection in
connector (141) measure gnd. brake circuit 97AL between
resistance to ground at switch and connectors (273) and
circuit 97AL. circuits (141) then repair.
check
good.

Testing Cruise On/Off Switch

Inspect circuits and connectors as outlined in Before Troubleshooting.

NOTE – Use the EZ-Tech or PRO-LINK 9000 EST to check cruise on/off switch operation. If the EST
indicates the cruise on/off switch is not operating properly, perform this procedure.

Table 63 Testing Cruise On/Off Switch

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector Cruise <2 ohms. Go to next Replace cruise on/off
(435) from on/off switch. on/off step. switch.
With switch in position, switch, 5
measure resistance to 6.
between terminals 5 and
6.
2. Off With switch in position, Cruise >100K Go to next Replace cruise on/off
measure resistance on/off ohms. step. switch.
between terminals 5 and switch, 5
6. to 6.
3. Off To test switch panel light Go to next Replace cruise on/off
function, connect 12V step. switch.
lead to terminal 7 and
gnd. terminal 8. Does
light turn on?

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Table 63 Testing Cruise On/Off Switch (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off Disconnect ECM (273), >100K Go to next Locate short to gnd in
connector (273) from 97AE to ohms. step. circuit 97AE between
the ECM. At connector gnd. connectors (273) and
(273) measure resistance (435), then repair.
from terminal F2, (circuit
97AE) to gnd.
5. Off At connector (435), (435), <5 ohms. Go to next Locate open or poor
measure resistance to 97-GC to step. connection in gnd. path
gnd. at circuit 97-GC. gnd. to negative battery
terminal for circuit
97-GC, then repair.
6. Off Connect (435) to cruise (273), <5 ohms. The cruise Locate open or
on/off switch and turn 97AE to on/off poor connection in
switch to position. At gnd. switch and circuit 97AE between
connector (273) measure circuits connectors (273) and
resistance of F2, (circuit check (435), then repair.
97AE) to gnd. good.

Testing Cruise Set/Resume Switch And Circuits

Inspect circuits and connectors as outlined in Before Troubleshooting.

NOTE – Use the EZ-Tech or PRO-LINK 9000 EST to check set/resume switch operation. If the EST
indicates the set/resume switch is not operating properly, perform this procedure.

Table 64 Testing Cruise Set/Resume Switch And Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (436) Cruise set/ <5 ohms. Go to next Replace cruise set/
from cruise set/resume resume step. resume switch.
switch. With switch in switch, 2
set position, measure to 3.
resistance between
terminals 2 and 3.
2. Off With switch in neutral Cruise set/ >100K Go to next Replace cruise set/
position, measure resume ohms. step. resume switch.
resistance between switch,
terminals 1, 2, and 3. between
1, 2 and 3.
3. Off With switch in resume Cruise set/ <5 ohms. Go to next Replace cruise set/
position, measure resume step. resume switch.
resistance between switch,
terminals 1 and 2. between
1 and 2.

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Table 64 Testing Cruise Set/Resume Switch And Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off To test switch light Go to next Replace cruise set/
function, connect 12V step. resume switch.
lead to terminal 7 and
gnd. terminal 8. Does
LED light turn on?
5. Off At connector (436) (436), <5 ohms. Go to next Locate open or poor
measure resistance to 97-GB to step. connection in circuit
ground at circuit 97-GB. gnd. 97-GB to gnd. at
negative battery
terminal, then repair.
6. Off Disconnect ECM (273), >100K Go to next Locate short to ground
connector (273) from 97AA to ohms step. in circuit 97AA, then
the ECM. Measure gnd. repair.
resistance G3, (circuit
97AA), to ground.
7. Off Measure resistance from (273), >100K Go to next Locate short to ground
J1, (circuit 97AB), to 97AB to ohms step. in circuit 97AB, then
ground. gnd. repair.
8. Off With set/resume switch (273), >100K Go to next Locate short between
disconnected, at 97AA to ohms. step. circuits 97AA and
connector (273) measure 97AB 97AB, then repair.
resistance between
terminal G3 and J1,
(circuit 97AA to 97AB).
9. On At connector (273), (273), <1 volt. Go to next Locate short to
measure voltage from J1, 97AB to step. unwanted voltage
(circuit 97AB), to ground. gnd. source, then repair.
10. On At connector (273), (273), <1 volt. Go to next Locate short to
measure voltage from 97AA to step. unwanted voltage
G3, (circuit 97AA), to gnd. source, then repair.
ground.
11. Off At connector (273) use (436), <5 ohms. Go to next Locate open or
test lead to jumper 97AA to step. poor connection in
terminal G3, circuit 97AA, 97-GB. circuit 97AA between
to ground. At connector connectors (436) and
(436) measure resistance (273), then repair.
between circuits 97AA
and 97-GB.
12. Off At connector (273) use (436), <5 ohms. The Locate open or
test lead to jumper 97AB to cruise set/ poor connection in
terminal J1, (circuit 97-GB. resume circuit 97AB between
97AB), to ground. At switch and connectors (436) and
connector (436) measure circuits (273), then repair.
resistance between check
circuits 97AB and 97-GB. good.

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3.6. VEHICLE SPEED SENSOR (VSS)

Inspect circuits and connectors as outlined in Before Troubleshooting. When monitoring engine functions using
the EZ-Tech or PRO-LINK 9000 EST, if the vehicle is moving, EZ-Tech or PRO-LINK 9000 will display vehicle
speed if the system is working properly.

Inspecting And Adjusting the Adjustable Vehicle Speed Sensor (VSS)

1. Disconnect engine harness connector (250) from the sensor. Loosen the locknut and remove the sensor.
The harness connector and sensor should be free of damage or corrosion. Remove any metal shavings or
debris from the sensor.

2. To install the sensor, turn in until the sensor contacts the transmission speedometer gear, then back out
one full turn. Tighten locknut to 15 ft-lbs. (20.3 N•m). This assures that the sensor is adjusted properly
for the next test.

Testing Vehicle Speed Sensor (VSS)

To perform this test construct two test leads using terminals (1680205C1) and suitable length of 16GA wire.

WARNING – A jack must never be used alone to support vehicle. The jack may lower and
serious injury could result. Always support vehicle with floor jacks. Always block wheels to prevent
vehicle from moving.

WARNING – EXTREME CAUTION should be used to prevent personal injury resulting from
contact with rotating vehicle wheels when connecting test leads.

Table 65 Testing Vehicle Speed Sensor (VSS)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With VSS (250), VSS >100K Go to next Replace VSS (Refer
disconnected, use terminals ohms. step. to Inspecting and
test lead to measure to gnd. Adjusting the Vehicle
resistance to ground at Speed Sensor (VSS)
both sensor terminals. preceding.
2. Off Use test leads and VSS 600 to Go to next Replace VSS, refer
measure resistance between 900 step. to Inspecting and
between VSS (250) terminals. ohms Adjusting the Vehicle
sensor terminals. with Speed Sensor (VSS)
adjustable preceding.
speed
sensor.

1500 to
3500 with

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Table 65 Testing Vehicle Speed Sensor (VSS) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
non-adjustable
sensor.
3. Off Block front wheels and Go to next
place rear axles on floor step.
stands.
4. Off Use AC voltmeter with Go to next
sufficient length leads to step.
avoid personal contact
with rotating vehicle
wheels during this test.
Connect meter leads to
test leads.
5. Off Run engine at idle speed, VSS >2.0 VSS Replace VSS, refer
with transmission in high across Volts AC. checks to Inspecting and
gear. Measure voltage terminals good. Adjusting the Vehicle
across the two sensor Speed Sensor (VSS)
terminals. preceding. NOTE:
Improper adjustment
will cause low, erratic,
or no sensor output.

Testing Vehicle Speed Sensor (VSS) Circuits To ECM

Table 66 Testing Vehicle Speed Sensor (VSS) Circuits To ECM

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With VSS sensor (250) (273), >100K Go to next Locate short to ground,
disconnected, remove 97AJ to ohms. step. then repair.
ECM connector (273) gnd.
from ECM. At connector
(273) measure resistance
to ground at terminal E2,
(ciruit 97AJ).
2. Off At connector (273) (273), >100K Go to next Locate short to ground,
measure resistance to 97AK to ohms. step. then repair.
ground at terminal E3, gnd.
(circuit 97AK).
3. Off At connector (273) (273), >100K Go to next Locate short between
measure resistance 97AJ to ohms. step. circuits 97AJ and 97AK,
between terminals E2 97AK. then repair.
and E3, (circuits 97AJ
and 97AK).

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Table 66 Testing Vehicle Speed Sensor (VSS) Circuits To ECM (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off At connector (273) (273), <1 volt. Go to next Locate short to
measure voltage from 97AJ to step. unwanted voltage
E2, (circuit 97AJ), to gnd. source, then repair.
ground.
5. Off At connector (273) (273), <1 volt. Go to next Locate short to
measure voltage from 97Ak to step. unwanted voltage
E3, circuit 97AK, to gnd. source, then repair.
ground.
6. Off At connector (250), use (273), <5 ohms Go to next Locate open or
test leads to connect 97AJ to step. poor connection in
circuit 97AJ to gnd. At gnd. circuit 97AJ between
connector (273) measure connectors (250) and
resistance from E2, (273), then repair.
(circuit 97AJ), to ground.
7. Off At connector (250), use (273), <5 ohms. The VSS Locate open or
test leads to connect 97AK to circuits poor connection in
circuit 97AK to ground. At gnd. between circuit 97AK between
connector (273) measure connectors connectors (250) and
resistance from E3, (273) and (273), then repair.
(circuit 97AK), to ground. (250)
check
good.

3.7. ENGINE BRAKE SYSTEM

Inspect circuits and connectors as outlined in Before Troubleshooting.

Testing Engine Brake Switches and Circuits

Table 67 Testing Engine Brake Switches and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector Engine <2 ohms. Go to next Replace the switch.
(434) from on/off switch. brake step.
With switch in position on/off
measure resistance switch, 5
between terminals 5 and to 6.
6.
2. Off With switch in position, Engine >100K Go to next Replace the switch.
measure resistance brake ohms. step.
between terminals 5 and on/off
6. switch, 5
to 6.

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Table 67 Testing Engine Brake Switches and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
3. Off To test switch light Go to next Replace the switch.
function, connect 12V step.
lead to terminal 7, and
gnd. to terminal 8. Does
LED light turn on?
4. Off At connector (434) (434), <5 ohms. Go to next Locate open or poor
measure resistance to 24-GA to step. connection in circuit
ground at circuit 24-GA. gnd. 24-GA or path to
ground at negative
battery terminal, then
repair.
5. Off Reconnect on/off switch (433), <5 ohms. Go to next Locate open or
to connector (434) 24AJ to step. poor connection in
and place in position. gnd. circuit 24AJ between
Remove connector connectors (434) and
(433) from engine brake (433), then repair.
selector switch. At (433)
measure resistance from
24AJ to gnd.
6. Off With engine brake Engine <5 ohms. Go to next Replace the switch.
selector switch in 6 brake step.
cyl. position, measure selector
resistance between switch, 2
terminals 2 and 6. to 6.
7. Off With engine brake Engine <5 ohms. Go to next Replace the switch.
selector switch in 6 brake step.
cyl. position, measure selector
resistance between switch, 2
terminals 2 and 3. to 3.
8. Off With engine brake Engine <5 ohms. Go to next Replace the switch.
selector switch in 2 brake step.
cyl. position, measure selector
resistance between switch, 2
terminals 2 and 3. to 3.
9. Off With engine brake Engine <5 ohms. Go to next Replace the switch.
selector switch in 4 brake step.
cyl. position, measure selector
resistance between switch, 2
terminals 2 and 6. to 6.
10. Off To test switch light Go to next Replace the switch.
function, connect 12V step.
lead to terminal 7, and
gnd. terminal 8. Does
LED light turn on?

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Table 67 Testing Engine Brake Switches and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
11. Off Remove connector (273), K2 >100K Go to next Locate short to ground.
(273) from the ECM. At to gnd. ohms. step. in circuit, then repair.
connector (273) measure
resistance to gnd. at
terminal K2.
12. Off At connector (273) (273), K3 >100K Go to next Locate short to ground
measure resistance to to gnd. ohms. step. in circuit, then repair.
gnd at terminal K3.
13. Off At connector (273) (273), K2 >100K Go to next Locate short between
measure resistance to K3. ohms. step. circuits 24AF and
between terminals K2 24AE, then repair.
and K3.
14. On At connector (273) (273), K2 <1 volt. Go to next Locate short to
measure voltage at to gnd. step. unwanted voltage
terminal K2 to ground. source, then repair.
15. On At connector (273) (273, K3 <1 volt. Go to next Locate short to
measure voltage at to gnd. step. unwanted voltage
terminal K3 to ground. source, then repair.
16. Off At connector (273) use (433), <5 ohms. Go to next Locate open or
test lead to jumper K2 to 24AE to step. poor connection in
gnd. At connector (433) gnd. circuit 24AE between
measure resistance to connectors (273) and
gnd. at circuit 24AE. (433) then repair.
17. Off At connector (273) use (433), <5 ohms. The Locate open or
test lead to jumper K3 to 24AF to engine poor connection in
gnd. At connector (433) gnd. brake circuit 24AF between
measure resistance to switches connectors (273) and
gnd. at circuit 24AF. and (433) then repair.
circuits
check
good.

3.8. DIAGNOSTIC ON/OFF/SHUTDOWN OVERRIDE SWITCH (260)

Refer to Operation Section for operation description.

Testing Diagnostic On/Off/Shutdown Override Switch

Inspect circuits and connectors as outlined in Before Troubleshooting.

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Table 68 Testing Diagnostic On/Off - Shutdown Override Switch

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (260) Shutdown <5 ohms. Go to next Replace the switch.
from the on/off shutdown override step.
override switch. With switch, 5
switch in on position, to 6.
measure resistance
between terminals 5 and
6.
2. Off With switch in off position, Shutdown >100K Go to next Replace the switch.
measure resistance override ohms. step.
between terminals 5 and switch, 5
6. to 6.
3. Off To test switch light Go to next Replace the switch.
function, connect 12V step.
lead to terminal 7, and
ground terminal 8. Does
LED light turn on?
4. Off At connector (260) (260), <5 ohms. Go to next Locate open or poor
measure resistance of 97-GD to step. connection in circuit
circuit 97-GD to ground. gnd. 97-GD or path to
ground at negative
battery terminal, then
repair.
5. Off Remove connector (273) (260), <5 ohms. The Locate open or
from ECM. At (273) 97AU to shutdown poor connection in
use test lead to jumper gnd. override/ circuit 97AU between
terminal G1 to ground. At diagnostic connectors (273) and
connector (260) measure switch and (260), then repair.
resistance from circuit circuits
97AU to ground. check
good.

3.9. PARK BRAKE (IDLE TIMER) SWITCH (268)

Inspect circuits and connectors as outlined in Before Troubleshooting.
Testing Park Brake Switch (268) and Circuits

NOTE – Vehicle air system must be fully charged for this test.

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Table 69 Testing Park Brake Switch (268) and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector Park <5 ohms. Go to next Replace the switch.
(268) from the park brake step.
brake switch. With park switch,
brake applied, measure across
resistance across switch terminals.
terminals.
2. Off With park brake applied, Park >100K Go to next Replace the switch.
measure resistance brake ohms. step.
to gnd at both switch switch,
terminals. terminals
to gnd.
3. Off Release park brake Park >100K Go to next Replace the switch.
and measure resistance brake ohms. step.
between switch terminals. switch,
across
terminals.
4. Off At connector (268) (268), <5 ohms Go to next Locate open or poor
measure resistance of 97-GE to step. connection in circuit
97-GE to ground. gnd. 97-GE or path to
ground at negative
battery terminal, then
repair.
5. Off Remove connector (273) (273), H2 >100K Go to next Locate short to ground
from ECM. At connector to gnd. ohms. step. in circuit 97AV between
(273) measure resistance connectors (273) and
of H2 to ground. (268), then repair.
6. On At connector (273) (273), H2 <1 volt. Go to next Locate short to
terminal H2, measure to gnd. step. unwanted voltage
voltage to ground. source in circuit 97AV,
then repair.
7. Off Connect (268) to park (273), H2 <5 ohms. Park brake Locate open or
brake switch, and apply to gnd. (idle timer) poor connection in
park brake. At connector switch circuit 97AV between
(273) measure resistance (268) and connectors (273) and
to ground at terminal H2. circuits (268), then repair.
check
good.

3.10. TESTING LOW COOLANT SENSOR CIRCUITS

When Detroit Diesel diagnostic codes are logged indicating a low coolant condition or a coolant sensor circuit
fault check for proper coolant levels. If coolant levels are not low, this test should be performed.

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Table 70 Testing Low Coolant Sensor and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect ECM (273) >100K Go to next Locate short in circuit
connector (273) from circuit 34 ohms. step. 34, then repair.
the ECM and disconnect to gnd.
(278) from the coolant
probe. Measure the
resistance from (273)
terminal H3, circuit 34, to
ground.
2. Off At (278), place a jumper (273) <5 ohms. Low Locate open in circuits
between terminals A terminal coolant 34 or 34-G, then repair.
and B. Measure the H3 and circuits
resistance between ECM gnd. check
connector (273) terminal good. Go
H3 and ground. to next
step.
3. Off Replace coolant probe.
If problem persists have
a Detroit Diesel dealer
diagnose ECM operation.

3.11. ECM POWER SUPPLY (SWITCHED AND UNSWITCHED)

Inspect ECM power and ground circuits and connectors as outlined in Before Troubleshooting.

Testing Unswitched Battery Power To ECM At Connector (676)

Table 71 Testing Unswitched Battery Power To ECM At Connector (676)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove and check the Fuses <1 ohm. Go to next Locate cause of
two 15A power fuses near step. overload condition,
located near batteries for batteries. then repair. Replace
open condition. fuse(s).
2. Off Re-install two 15A fuses. (676), A 12 ± 1.5 Go to next Locate cause of no
At connector (676) to gnd. volts. step. or low voltage in
measure voltage to circuit 14C or 14B from
ground at terminal A. battery, then repair.

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Table 71 Testing Unswitched Battery Power To ECM At Connector (676) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
3. Off At connector (676) (676), C 12 ± 1.5 Go to next Locate cause of no
measure voltage to to gnd. volts. step. or low voltage in
ground at terminal C. circuit 14D or 14A from
battery, then repair.
4. Off At connector (676) (676), C 12 ± 1.5 ECM At terminal (B, D, or E)
measure voltage between to B, D, volts. power where less than battery
terminal C and terminal and E. connector voltage is present,
B, D, and E. circuits locate open in circuit
test good. between connector
(676) and negative
battery terminal, the
repair.

Testing Switched Battery Power To ECM

Table 72 Testing Switched Battery Power To ECM

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove and check fuse F6-D. <1 ohm. Go to next Locate cause of
F6-D for open condition. step. overload condition,
then repair. Replace
fuse.
2. Off/ Re-install fuse F6-D. (273), B3 12 ± 1.5 Switched Go to next step.
On Remove connector (273) to gnd. volts. voltage
from ECM. Turn key on circuit
and at (273) terminal to ECM
B3 measure voltage to connector
ground. (273) is
good.
3. On At fuse F6-D/circuit F6-D/ 12 ± 1.5 Locate Locate cause of no
13D, measure voltage to 13D to volts. open in or low voltage at fuse
ground. gnd. circuit F6-D, then repair.
13D, then
repair.

4. COMPONENT LOCATIONS
(B1) Battery Stud. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . . Power Distribution Panel
(B2) Battery Stud. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . . Power Distribution Panel
(2) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Above Connector 3
(3) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Below Connector 2
(94) Back-Up Light Switch. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . . . . . On Transmission
(137) 6-Way Data Link Connector. . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(141) Ser. Brake Switch/Cruise Switch. . . . . . . . . . . . .. . . . . . Dash Panel, Lt. Side, Engine Side
(190) Cab Overlay to Elect. Eng. Harness. . . . . . . . .. . . . . . Right Instrument Panel
(227) Fan Solenoid.. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .. . . . . . At Front of Engine

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256 7 DETROIT DIESEL SERIES 60 ENGINES

(228) Refrigerant Pressure Switch. . . . . . . . . . . . . . . . . .. . . . . . On A/C Compressor, On Engine

(235) Transmission Oil Temp. (Inline).. . . . .. . . . . .. . .. . . . . . On Front of Transmission
(250) Vehicle Speed Sensor. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . On Transmission
(260) Det. Diesel Eng. Override Diag. On/Off
Switch . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. ... . . . . . At Switch Cluster
(267) Detroit Diesel Throttle Pos. Sensor. . . . . . . . . .. . . . . . On Engine
(268) Det. Diesel Idle Timer/Park Brake Sw. . . . . . .. . . . . . Behind Switch Cluster
(273) Detroit Diesel ECM Connector. . . . . . . . . . . . . . . .. . . . . . To ECM Mounted on Dash Engine Side
(278) Detroit Diesel Low Coolant Switch. . . . . . . . . . .. . . . . . To Engine Harness
(294) Clutch Switch Connector. . . . . . . . . . . . . . . . . . . . . .. . . . . . Near Clutch Switch
(403) J1922 Data Link. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Dash Panel Right Side
(1160) ECM Comm. W/ Series 60 Detr. . . . . . . . . . . . .. . . . . . Inline near ECM
(433) Engine Brake Selector Switch. . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(434) Engine Brake On/Off Switch. . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(435) Cruise On/Off Switch . . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . At Switch Cluster
(436) Cruise Set/Resume Switch. .. . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(494) I1 Ignition Adapter. .. . . . .. . . . .. . . . .. . . . .. . . . .. . .. . . . . . Behind Fuse Panel
(504) L2 Panel Light Feed Adapter. .. . .. . .. . .. . .. . ... . . . . . Behind Instrument Panel/Switch Breakout
(506) L4 Panel Lights Ground Adapter. . . . . . . . . . . . .. . . . . . Behind Instrument Panel/Switch Breakout
(514) Data Link - Positive. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel/Behind Cluster
(515) Data Link - Negative. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel/Behind Cluster
(640) Stop Light Switch. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . .. . . . . . Dash Panel, Left Side, Engine Compartment
(675) ECM Power (Inline) W/Series 60. . . . . . . . . . . . .. . . . . . Near ECM
(676) ECM 6-Way Power Connector. . . . . . . . . . . . . . . .. . . . . . Near ECM

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 7 DETROIT DIESEL SERIES 60 ENGINES 257

Figure 90 Engine Wiring

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258 7 DETROIT DIESEL SERIES 60 ENGINES

1. DASH PANEL (VIEWED FROM INSIDE ENGINE COMPARTMENT)

2. (141) BRAKE SWITCH
3. (640) STOP LIGHT SWITCH
4. (190) ELECTRONIC ENGINE CONNECTOR
5. RIGHT HAND DASH PANEL GROUND STUD
6. (3) ENGINE CONNECTOR
7. (2) CHASSIS HARNESS CONNECTOR
8. POWER DISTRIBUTION PANEL
9. B1 AND B2 BATTERY STUDS
10. SWITCHES
11. RIGHT GAUGE CLUSTER
12. SPEEDOMETER / TACHOMETER CLUSTER
13. LEFT GAUGE CLUSTER
14. (514) DATA LINK CONNECTOR
15. (515) DATA LINK CONNECTOR
16. (137) DATA LINK
17. FRONT END HARNESS CONNECTOR
18. THROTTLE PEDAL
19. (267) THROTTLE PEDAL CONNECTOR
20. (268) IDLE TIMER PARK BRAKE SWITCH
21. CLUTCH SWITCH
22. (294) CLUTCH SWITCH CONNECTOR

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 7 DETROIT DIESEL SERIES 60 ENGINES 259

Figure 91 Engine Wiring

1. (190) ELECTRONIC ENGINE CONNECTOR
2. RH DASH PANEL GROUND STUD
3. (3) CHASSIS HARNESS CONNECTOR
4. (2) CAB/ENGINE HARNESS CONNECTOR
5. CIRCUIT 14A TO (B1) BATTERY STUD
6. START MAGNETIC SWITCH
7. CIRCUIT 17D USED WITH THERMAL OVERCRANK SYSTEM
8. (402) LOW COOLANT LEVEL SWITCH
9. LH DASH PANEL GROUND STUD
10. (1) FRONT END HARNESS CONNECTOR
11. (410) FAN SOLENOID RELAY
12. ENGINE HARNESS

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260 7 DETROIT DIESEL SERIES 60 ENGINES

Figure 92 Engine Wiring

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 7 DETROIT DIESEL SERIES 60 ENGINES 261

1. TO BATTERY CABLE AND STARTER HARNESS

2. CIRCUIT 97–G
3. ECM CONNECTOR (273)
4. J1939 & J1922 CONNECTOR (1160)
5. ECM POWER CONNECTOR (676)
6. ECM
7. CIRCUIT 21A
8. CIRCUITS 11–GA, 11–GU, 11–GS & 2–G
9. STARTER
10. ECM
11. TO OTHER SIDE OF ENGINE
12. TO ENGINE WIRING AT DASH PANEL
13. TO TRANSMISSION
14. CIRCUIT 17C
15. FUSIBLE LINK, CIRCUIT 2
16. TO FRAME GROUND
17. TO ECM
18. CIRCUIT 11–GS
19. CIRCUIT 11–GA
20. CIRCUIT 2–G
21. CIRCUIT 11–GU

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262 7 DETROIT DIESEL SERIES 60 ENGINES

Figure 93 Engine Wiring

1. CIRCUIT 77C
2. TO OTHER SIDE OF ENGINE
3. CIRCUITS 23 & 23D
4. JUMPER USED WITHOUT AIR CONDITIONING
5. AIR LINE TO FAN CLUTCH (FROM FAN SOLENOID)

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 7 DETROIT DIESEL SERIES 60 ENGINES 263

Figure 94 Engine Wiring, Alternator Effects

1. CIRCUIT 2
2. ENGINE HARNESS
3. CIRCUIT 2-G
4. CIRCUIT A2

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264 7 DETROIT DIESEL SERIES 60 ENGINES

Figure 95 Engine Wiring, Transmission Effects

1. TO ENGINE
2. TRANSMISSION OIL TEMPERATURE CONNECTOR (235)
3. BACK-UP LIGHT SWITCH (94)
4. CIR 97AJ & 971K
5. VEHICLE SPEED SENSOR
6. NEUTRAL POSITION SWITCH

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Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .267

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .267
2.1. ECM POWER CIRCUITS.. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .268
2.2. ATA DATA LINK CONNECTOR. . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .268
2.3. DIAGNOSTIC ON/OFF SWITCH. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .269
2.4. IDLE/DIAGNOSTIC SWITCH. .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .269
2.5. ELECTRONIC ACCELERATOR PEDAL ASSEMBLY. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .269
2.6. COOLANT LEVEL SWITCH.. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .270
2.7. CRUISE CONTROL. .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .270
2.8. CLUTCH SWITCH.. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .271
2.9. VEHICLE SPEED SENSOR. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .271
2.10. ENGINE BRAKE. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. .271
2.11. ANTILOCK BRAKE INTERFACE. .. .. .. . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .272
2.12. GAUGES AND WARNING LIGHTS. . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .272

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .272
3.1. ONBOARD DIAGNOSTICS WITH ENGINE RUNNING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .272
3.2. PERFORMING A DIAGNOSTIC CHECK WITH THE ENGINE OFF. . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .273
3.3. COMPULINKTM.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .274
3.4. EZ-TECH OR PRO-LINK ELECTRONIC SERVICE TOOL (EST). .. . . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .274
3.5. INSPECTING INTERNATIONAL ENGINE HARNESS ECM CONNECTOR (252). . . . . . . . . . . . . . .275
3.6. RELAYS.. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. .277
3.7. TESTING RELAY. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .277
3.8. ACCELERATOR PEDAL TPS/IVS.. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .278
Testing Throttle Position Sensor (TPS). . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .278
Testing Idle Validation Switch (IVS).. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .279
Testing Accelerator Pedal (TPS/IVS) System for "Short or Open" Circuits. . . . . . . . . . . . . .280
Testing TPS/IVS Circuits for Continuity. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .281
Accelerator/ECM Calibration.. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .283
3.9. LOW COOLANT SWITCH. .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .283
Testing Low Coolant Level Switch and Circuits.. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .283
3.10. POWER SUPPLY CIRCUITS TO ECM.. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .284
Testing Unswitched Battery Power Circuits and ECM Ground Circuit. . . . . . . . . . . . . . . . . . . .284
Testing Switched Ignition Power To ECM . .. . .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. . .. .. .. . .. .. .. . .. .. .285
3.11. SERVICE BRAKE AND CLUTCH SWITCHES. .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. .286
Testing Clutch Switch.. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .286
Testing Clutch Switch Circuits for “Open and Short” Condition. . .. . .. . . .. . .. . . .. . .. . . .. . .287
Testing Clutch Switch Circuits For Continuity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .288
Testing Service Brake Switch (141). . .. .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. .289
Testing Service Brake Switch Circuits for "Open and Short" Condition.. .. . .. .. . .. .. . .. .290
Testing Service Brake Switch Circuits for Continuity. .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .291
3.12. ENGINE BRAKE. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. .292
Testing Engine Brake Components and Circuits. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .292
Testing Engine Brake Switches. . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .292
3.13. ATA DATA LINK CONNECTOR (137) AND SPEEDOMETER/TACHOMETER INPUT
CIRCUITS. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .293

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Testing Diagnostic Connector Power and Ground Circuits. . . . .. . . . . . .. . . . . .. . . . . .. . . . . .. . .293

Testing Data Link Circuits Between Diagnostic Connector, ECM and
Speedometer/Tachometer Unit. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . .. . . . . . .294
3.14. DIAGNOSTIC SWITCHES. .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. ..295
Testing Diagnostic On/Off Switch and Circuit. . .. . . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . .296
Testing Idle/Diagnostic Switch (243) and Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297
3.15. CRUISE CONTROL. .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. .299
Testing Cruise Control On/Off Switch and Circuits. .. .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . ..299
Testing Cruise Set/Resume Switch and Circuits. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. .301
3.16. VEHICLE SPEED SENSOR.. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ..302
Inspecting and Adjusting the Vehicle Speed Sensor (VSS).. . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . .302
Testing Vehicle Speed Sensor. . .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . ..303
Testing Vehicle Speed Sensor Circuits To ECM. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. .304

4. COMPONENT LOCATIONS. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . ..305

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 267

1. DESCRIPTION
The N14 controller provides many engine/vehicle functions including:

• Cruise/PTO Controls
• Tachometer/Speedometer Input To Gauges
• Idle Shutdown
• Adjustable Low Idle Speed (In-Cab)
• Engine Cooling Fan Control
• Self Diagnostics
• Engine Protection System
• Engine Brake Control

Refer to the Cummins Engine Manual furnished with the vehicle for additional feature information.

Since each engine control system is electronically programmable to individual owner specifications, the
operating parameters will vary from vehicle to vehicle. These parameters include: maximum cruise speed,
shift schedules, governor type (automotive type or variable speed), idle RPM, full engine shutdown as part
of the engine protection system and many others.

The electronic control module (ECM) is the control center of the CELECT system. The ECM receives input
from Cummins and International sensors and switches, processes the information, then used electrical signals
to control engine and vehicle functions.

The ECM receives inputs from International installed components including:

• Vehicle Speed Sensor (VSS)

• Throttle Position Sensor (TPS)
• Idle Validation Switch (IVS)
• Service Brake Switch
• Clutch Switch
• Low Coolant Level Switch
• ABS/Traction Control Controller
• CELECT Cab Switches

The ECM receives information from the sensors and switches and sends signals to the injectors, fuel shutoff
valve and engine brake relay.

2. OPERATION
Refer to Cummins N14 CELECT — ENGINE CONTROLS circuit diagrams in CTS-5298 or S08225.

The ECM is connected to the International electrical system at three points (or four points with antilock
brakes installed).

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268 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM

A. International engine harness 28–way ECM connector (252) connects to ECM port B. This
connector links International sensors, switches and the diagnostic connector to the ECM.
B. International 21–way connector (251) connects to the Cummins sensor harness. This connector
links the International installed engine brake components, low coolant switch, fan controls and
switched voltage to the ECM.
C. The International ECM power connector (216) connects to the Cummins actuator harness. This
connector supplies the unswitched power to the ECM and provides an ECM ground circuit to the
engine ground stud.
D. Additionally, with ABS/traction control system, the International ECM connector (252), connects
to the Cummins sensor harness located near the front of the ECM. J1922 Data Link connector
(403) connects to the ABS system.

2.1. ECM POWER CIRCUITS

Power is supplied at all times to the ECM from the cranking motor solenoid B+ terminal. Circuits 97B and 97C
deliver power on the International harness through the ECM power connector (225) and the Cummins harness
to the ECM. The Cummins harness has a 10A inline fuse in each circuit.

The ECM is grounded through the Cummins harness, ECM power harness connector (225) and circuit 97–G to
the engine ground stud. The engine ground stud is connected to the cranking motor ground stud, frame rail
and negative battery terminal.

Turning the key switch to the ignition or start position applies power to circuit 13, 13Z, 5A fuse F6–D and
circuit 13D to the 21–way ECM connector (251).

2.2. ATA DATA LINK CONNECTOR

The six pin ATA data link connector (137) allows an electronic service tool (EST) to communicate with the
ECM. The data link carries serial data transmissions between the ECM and the electronic service tool, and
between the ECM and the speedo/tachometer cluster. Thus, the ECM provides vehicle and engine information
to the speedo/tachometer and the EST.

The ATA data link connector (137), which is located on the left instrument panel, has circuits in four of the
six cavities. The data link circuits are a twisted wire pair because twisting the wires helps shield them from
interference. The circuits are as follows:

Circuit 98A(+) is the positive data link connection, and it is fed by the positive data link connector (514), the
jumper bus bar, circuit 98(+), connector (190), and circuit 98(+) coming from the ECM connector (252).

Circuit 98C(-) is the negative data link connection, and it is fed by the negative data link connector (515), the
jumper bus bar, circuit 98B(-), connector (190) and circuit 98B(-) coming from the ECM connector (252).

Circuit 97DL is a 12 volt feed and is fed from the battery adapter (498), circuit 14BK and 20A fuse F5–D.
Thus it provides power for the electronic service tool.

Circuit 11–GR, 11–GT is connected to the panel lights ground adapter (506), and provides a ground for the
electronic service tool.

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 269

2.3. DIAGNOSTIC ON/OFF SWITCH

A lighted diagnostic on/off switch is provided for on-board diagnostics. The switch is connected to the ECM
common/ground connection by way of ECM connector (252), circuits 97–G and 97–GA, connector (190), and
circuits 97–GA and 97–GE. Moving the switch to the on position, closing the switch, applies the ground to
circuit 97AM, connector (190) and circuit 97AM to the Cummins engine connector (251). This tells the ECM
that the diagnostic on/off switch has been turned on. Thus the ECM will switch modes to display fault codes or
the absence of codes by flashing the engine warning light and the stop engine light.

2.4. IDLE/DIAGNOSTIC SWITCH

The lighted two-position momentary idle/diagnostic switch is a dual function switch. The switch adjusts the
low engine idle speed and is also used during on-board diagnostics (when the diagnostic switch is in the on
position) to move through the diagnostic fault code list.

The engine idle speed can be adjusted by the switch in increments of 25 rpm by toggling the switch. Maximum
idle speed is 800 rpm and minimum idle speed is 550 rpm. When the idle has been changed and the key
turned off, the new setting is saved in memory. This feature is owner selected and can be turned off with an
electronic service tool.

The switch is connected to the ECM common/ground connection by way of ECM connector (252), circuits
97–G and 97–GA, connector (190) and circuits 97–GA and 97–GD. Momentarily placing the switch in the
increment position applies ground to circuit 97AV, connector (190) and circuit 97AV to the ECM (252). This
causes the engine idle rpm to increase 25 rpm.

Momentarily placing the switch in the decrement position applies ground to circuit 97AU, connector (190) and
circuit 97AU to the ECM (252). This causes the engine idle rpm to decrease 25 rpm.

2.5. ELECTRONIC ACCELERATOR PEDAL ASSEMBLY

CELECT engines utilize an electronic accelerator pedal assembly that includes an integrated throttle position
sensor (TPS) and idle validation switch (IVS). The accelerator pedal assembly is serviceable, to the extent that
the IVS switch is replaceable without replacing the whole assembly.

The TPS is attached to the accelerator pedal and acts like a potentiometer. Movement of the pedal results in
a variable signal being sent to the ECM that is proportional to pedal position. A 5 volt signal from the ECM
connector (252) is applied to circuit 99A, connector (190), circuit 99A and the TPS/IVS (267). The variable
wiper signal (varies with pedal position) from TPS/IVS (267) is returned to the ECM over circuit 99, connector
(190), circuit 99 and ECM connector (252). This variable signal tells the ECM the position of the accelerator
pedal. The TPS (267) is grounded through circuit 99–GA, connector (190) and circuit 99–GA to the ECM (252).

NOTE – Any time the accelerator pedal sensor (TPS) is disconnected from the ECM with the key switch
on, the TPS and ECM must be recalibrated.

The IVS is used to indicate when accelerator pedal is in the low idle position and when the pedal is not in the
low idle position. A ground path from the ECM connector (252), circuits 97–G and 97–GA, connector (190),
circuits 97–GA and 99–GA is applied to the TPS/IVS (267).

When the accelerator is in the low idle position, the IVS (267) applies a ground signal to circuit 99B, connector
(190) and circuit 99B to the ECM (252). When the accelerator is not in the idle position, the IVS (267) applies a
ground signal to circuit 99C, connector (190) and circuit 99C to the ECM (252).

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270 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM

The ECM analyzes the signals received from the TPS and IVS to make certain that the signals fall within
certain parameters. For example: if the IVS signal indicates that the accelerator pedal is in the idle position,
the ECM expects to see a TPS signal that indicates that no throttle is applied. If it does not see a logical
response from both, a fault code may be logged.

The ECM and accelerator pedal must be calibrated to one another for proper engine response. Therefore,
the ECM and accelerator pedal must be calibrated when the accelerator pedal is initially installed, when an
accelerator pedal is replaced, when a new calibration is downloaded to the ECM, or when the accelerator
pedal wiring is disconnected at the pedal, the cab floor, or the ECM connector. To recalibrate the ECM and the
accelerator pedal, move the key switch to ignition position, slowly move the accelerator pedal from idle position
to fully depressed position and then release. Repeat this cycle two more times to assure proper calibration.

2.6. COOLANT LEVEL SWITCH

The coolant level switch is a fluid level actuated switch that sends two signals to the ECM, thus providing a
warning when coolant is being lost. It is mounted in the coolant surge tank. The coolant level switch is an
electronic switch that operates on the electrostatic or capacitance principle and cannot be tested with a
multimeter. The probe extends into the coolant and produces a change in capacitance when coolant displaces
air immediately surrounding the probe. This change is converted in the switch to an on/off solid state switch
closure indicating the absence or presence of coolant. The switch is electrically insulated providing a slick,
non-fouling surface as well as good electrical characteristics to prevent current flow into the coolant. The low
coolant level switch connects to the engine harness at connector (249). Four circuits from connector (249)
connect the low coolant switch to the ECM through the 21–way ECM connector (251).

The coolant level switch (249) receives a 5 volt signal on circuit 34B(5V) from the ECM (251). When the
coolant level is above the probe, the switch sends a high signal (3.5 volts minimum) on circuit 34A and a low
signal (0.5 volt maximum) on circuit 34 to the ECM (251).

When the coolant level is below the probe, the switch sends a low signal (0.5 volt maximum) on circuit 34A and
a high signal (3.5 volts minimum) on circuit 34 to ECM (251).

The low coolant level switch is grounded through circuit 34–G to ECM (251).

NOTE – The low coolant level switch cannot be tested with a multimeter in the ohmmeter mode. This is
due to the fact that the switch is an electronic switch and not a mechanical switch.

2.7. CRUISE CONTROL

The cruise control system has three modes of operation: off, standby and active. The off position of the on/off
switch turns cruise control off. The standby mode occurs when the driver switches the cruise control on/off
switch to the on position. The driver can then achieve the active mode by toggling the set/resume switch
after reaching the desired road speed.

Once the system is active, the driver can accelerate beyond the set speed by depressing the accelerator
pedal. When the pedal is released, cruise control is reactivated when the vehicle speed reaches the previously
set speed.

Cruise is deactivated and returns to the standby mode in several ways: the brake or clutch pedal is depressed,
the engine speed (rpm) drops below 1000 rpm, or the vehicle speed (mph) drops below 30 mph.

The resume switch can be used to reactivate cruise at the previous set speed or the set switch can be used
to establish a new set speed.

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While in the active mode, the coast feature is used to decrease vehicle speed and establish a new lower set
speed. By holding select switch in the coast position, vehicle speed decreases until the switch is released;
the speed at release becomes the new set speed.

While in the active mode, the accelerate feature is used to increase the vehicle speed and establish a new
higher speed. By holding the select switch in the accel position, vehicle speed increases until the switch is
released; the speed at release becomes the new set speed.

The lighted cruise control on/off switch (435) receives a ground signal on circuits 97–GC, 97–GA, connector
(259), circuits 97–GA, 97–G and 11–G from the negative battery terminal. In the on position, a ground signal is
sent from the switch on circuit 97AE, connector (190) and circuit 97AE to ECM connector (252) terminal 2.
This indicates to the ECM that the cruise control switch is in the on position. In the off position, circuit 97AE
returns to its 12 volt value, indicating to the ECM that the switch is off.

The lighted cruise set/resume switch is a momentary switch. This switch receives a ground signal on circuits
97–GB, 97–GA, connector (259), circuits 97–GA, 97–G and 11–G from the negative battery terminal. The
cruise selector switch sends a ground signal from the switch on circuit 97AB, connector (190) and circuit
97AB to the ECM connector (252) terminal 12 while in the set/accel position. In the resume/coast position,
the switch sends a ground signal by way of circuit 97AA, connector (190) and circuit 97AA to the ECM
connector (252) terminal 22.

2.8. CLUTCH SWITCH

The clutch switch (294) is a N.O. momentary switch and its contacts are held closed when the clutch pedal
is released.

The switch is provided a ground path over circuits 97–GH, 97–GA, connector (259), circuits 97–GA, 97–G and
11–G from the negative battery terminal. The clutch switch (294) sends a ground signal by way of circuit 97AH,
connector (190) and circuit 97AH to the ECM connector (252) terminal 4 while the clutch pedal is released.

2.9. VEHICLE SPEED SENSOR

The vehicle speed sensor (250) feeds a VSS signal to the ECM (252) by way of circuits 97A and 97AK.

Two types of sensors are available. The threaded (adjustable) sensor is used on most transmissions. A
push-in (non-adjustable) sensor is used on some transmissions.

2.10. ENGINE BRAKE

The lighted engine brake on/off switch (434) receives a ground signal on circuits 24–G, 97–GA, connector
(259), circuits 97–GA, 97–G and 11–G from the negative battery terminal. In the on position, a ground signal is
sent from the switch on circuit 24AD to engine brake selector switch (433).

When lighted switch (433) is placed in the first position, a ground is applied to circuit 24AE, connector (190),
and circuit 24AE to the ECM (252). This tells the ECM to enable the brake solenoid for the front two and rear
two cylinders on the N14E engine when braking is called for.

When switch (433) is placed in the second position, a ground is applied to circuit 24AF, connector (190) and
circuit 24AF to the ECM (252). This tells the ECM to enable the brake solenoid for the center two cylinders on
the N14E engine when braking is called for.

When switch (433) is placed in the third position, a ground is applied to circuit 24AF and 24AE to the ECM
(252). This tells the ECM to enable all solenoids and use all cylinders for braking.

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2.11. ANTILOCK BRAKE INTERFACE

If the vehicle is equipped with antilock brakes, information is shared with ABS controller module over a J1922
data link through connector (403), circuits 98Z and circuit 98Y(-) to the ECM (251).

2.12. GAUGES AND WARNING LIGHTS

Refer to separate gauge and warning lights sections in GROUP 08 — ELECTRICAL in the CTS-5000 Master
Service Manual for information on speedometer, tachometer, gauges and warning lights.

3. TROUBLESHOOTING
Refer to Cummins N14 CELECT — ENGINE CONTROLS circuit diagrams in CTS-5298 or S08225.

This section includes troubleshooting charts for International installed circuits and components that are part
of the CELECT Electronic Control system. To begin the troubleshooting process, refer to the appropriate
Cummins manual and follow their directions. If the Cummins diagnostics (fault codes) indicate that the suspect
circuits are International circuits or components, then use the charts in this section.

The EZ-Tech or Pro-Link 9000 EST can also be used to determine if the International switches and components
are working properly. If they are not, use a Fluke digital multimeter (DMM) to troubleshoot the circuits.

If the Cummins diagnostic codes or the EZ-Tech or the Pro-Link indicates a problem with International installed
circuits, the diagnostic tables in this chapter provide step-by-step test procedures.

A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 —
ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit, by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the position are generally not covered
in detail. It is assumed that the technician knows to check for a malfunctioning switch, relay, or
solenoid.

3.1. ONBOARD DIAGNOSTICS WITH ENGINE RUNNING

All CELECT vehicles have a yellow Engine Warning light and a red Engine Stop light located in the telltale
lights in the instrument cluster. Every time the key is turned to the ignition position, the lights come on for
several seconds as a system self-test and then turn off.

If the warning lights remain on, it is an indication that the ECM has detected a problem. The CELECT system
can show and record certain problems. The problems are shown as fault codes. The fault codes are recorded
in the ECM.

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If a fault is detected (becomes active) during vehicle operation, the driver is alerted by the illumination of
either the yellow Engine Warning light or the red Stop Engine light. The yellow Service/Check Engine light
may also be illuminated.

The yellow Engine Warning light turns on to warn the driver of an active component or system fault that should
be serviced as soon as possible to solve the problem, but the situation is not considered an emergency.

The red Stop Engine light turns on to warn the driver that there is a major CELECT system problem and the
vehicle should be stopped and engine shut down as soon as is safely possible.

The yellow Service/Check Engine light (engine protection system) turns on to warn the driver that:

A. Coolant temperature is out of range.

B. Oil temperature is out of range.
C. Oil pressure is out of range.
D. Intake manifold temperature is out of range.
E. Engine coolant level is below the acceptable level.

3.2. PERFORMING A DIAGNOSTIC CHECK WITH THE ENGINE OFF

A diagnostic check may be performed using the Diagnostic On/Off switch and Idle/ Diagnostic Inc/Dec switch.
Any error codes will be flashed through the red Engine Stop light and yellow Engine Warning light. If no errors
are found, both lights will stay on while the diagnostics switch is on. Consult the Cummins Operation and
Maintenance Manual furnished with the vehicle for exact procedures and fault code information.

To determine the fault codes use the following procedure:

1. Begin the procedure with the engine off.

2. Place the switch key in the off position.

3. Turn the diagnostic on/off switch to the on position.

4. Turn the key switch to run position (not crank).

5. Yellow Engine Warning light will flash once.

6. There will be a one to two second pause.

7. Red Engine Stop light will flash code with one or two seconds between digits.

8. Yellow Engine Warning light will flash indicating the end of that fault code, and then start over and
repeat the same fault code.

9. To go to the second fault code, move the Idle/Diagnostic Inc/Dec switch to the Inc position and then
release it. The process will then repeat itself as indicated in steps 5 through 8.

10. To move back to the last or previous fault code, move the Idle/Diagnostic Inc/Dec switch to the Dec
position and then release it. The process will then repeat itself as indicated in steps 5 through 8.

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11. To stop the diagnostics procedure, correct the faults or move the diagnostic on/off switch to off, and turn
the vehicle key switch to the off position.

NOTE – Cummins CELECT engine diagnostics must be run with the engine NOT RUNNING.

If BOTH the yellow Engine Warning and red Engine Stop lights come on momentarily and then go out, it is an
indication that engine faults are present.

If BOTH the yellow Engine Warning and red Engine Stop lights come on and stay on, it is an indication that
no engine faults are present.

NOTE – All Cummins fault codes are 3 digits.

For example, the yellow Engine Warning light flashes once. The red Engine Stop light flashes:

FLASH

Digit number one is 1. Then there is a pause.

FLASH — FLASH

Digit number two is 2. Then there is pause.

FLASH — FLASH — FLASH.

Digit number three is 3. Yellow Engine Warning lamp flashes once. The fault code is 123

3.3. COMPULINKTM
CELECT vehicles have a data link connected to the ATA data link connector (137) The Cummins CompulinkTM
electronic service tool can be connected to the connector to program owner-specified information into
the engine, monitor the system, and aid in troubleshooting the engine. Consult the Cummins CELECT
Troubleshooting and Repair Manual. The CompulinkTM may be available at the nearest Cummins Authorized
Service Center.

CompulinkTM must be used with a CELECT service cartridge to communicate with a CELECT engine. A
PACE or PT PACER cartridge will not work properly.

NOTE – On the Cummins CompulinkTM, since no alpha characters are available, use the up arrow and
down arrow to move through the alphabet.

3.4. EZ-TECH OR PRO-LINK ELECTRONIC SERVICE TOOL (EST)

The EZ-Tech or Pro-Link 9000 EST with the heavy duty standard program can also be used with the
International data link to read active and inactive fault codes through the data link. The use of the DDR or
specific codes are not discussed in this manual as the information is part of the EZ-Tech or Pro-Link 9000
documentation.

The EZ-Tech or Pro-Link 9000 can also be used to monitor operation of various switches and controls and
perform other diagnostic tasks. The specific capabilities and operating instructions are included in the EZ-Tech
or Pro-Link 9000 documentation.

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 275

3.5. INSPECTING INTERNATIONAL ENGINE HARNESS ECM CONNECTOR (252)

1. Remove connector (252) from the ECM, first removing the two capscrews. Carefully pull the connector
straight out of the ECM. The connector pins are numbered (see Figure below) and correspond to the
numbers on the circuit diagrams.

Figure 96 OEM Connector "B"

2. Inspect the connector for pushed back or expanded terminals in the following manner:
a. Insert the tool (Cummins part number 3823383) into each Amp connector (Tool In Connector Figure)
Do not force the tool into the connector.
b. A terminal that is not pushed back or expanded will have a surface to tool gap (Tool In Connector
Figure) of approximately 0.050 inch (1.3 mm). If the tool touches the connector, replace the terminal.
c. Push the tool into the terminal until the tool touches the connector (Surface Tool Gap Figure). Slowly
remove the tool from the terminal. A small resistance (6 to 10 ounces) must be felt (Tool Touching
Connector Figure). If the resistance is not felt, the terminal is expanded and must be replaced.
d. Repeat steps A through C to check for pushed back or expanded terminals for all terminals in the
ECM connector.
e. Inspect the connector pins in the ECM. If the pins are bent (Inspect Connector Pins Figure), have a
Cummins dealer replace the ECM.

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Figure 97 Tool In Connector

Figure 98 Surface Tool Gap

Figure 99 Tool Touching Connector

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Figure 100 Inspect Connector Pins

3.6. RELAYS
International circuits use suppressed relays for controlling power to load devices. The suppression feature (a
resistor circuit parallel to the relay coil) prevents voltage spikes from damaging electronic components in the
vehicle. These relays must be replaced with the correct International part.

Relays used in exposed areas such as the engine compartment are sealed relays and have a different part
number than those in the cab. The part number is embossed on the relay. There is also a circuit diagram of the
relay located on the relay body. The terminals are numbered on the relay in the same manner as in the circuit
diagrams. To test the relay, refer toTesting Relay.

3.7. TESTING RELAY

Table 73 Testing Relay
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With relay removed, Relay, 30 >100K Go to next Replace the relay.
measure resistance to 87. ohms. step.
between terminals 30 and
87.
2. Off Measure resistance Relay, 30 <2 ohms. Go to next Replace the relay.
between terminals 30 and to 87A. step.
87A.
3. Off Connect 12V lead to Go to next Replace the relay.
terminal 85 and ground step.
lead to terminal 86. Does
relay energize with audible
click?
4. Off With relay energized (step Energized <2 ohms. Relay Replace the relay.
3), measure resistance relay, 30 tests
between terminals 30 and to 87. good.
87.

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3.8. ACCELERATOR PEDAL TPS/IVS

The following four tests check the throttle position sensor (TPS), the idle validation switch (IVS) and the related
International cab and engine harness circuits connected to the ECM.

NOTE – The following four tests, Testing Throttle Position Sensor (TPS), Testing Idle Validation Switch
(IVS), Testing Accelerator Pedal (TPS/IVS) System for “Short or Open” Circuits and Testing TPS/IVS
Circuits for Continuity must be performed in sequence.

The tests should be performed if a Cummins fault code indicates a problem in the circuits or if the CompulinkTM
EZ-Tech or Pro-Link 9000 EST indicates that the TPS/IVS is not working properly while monitoring switches. If
CompulinkTM detects a fault with the IVS circuits while monitoring switches, the display would show Idle
Validation Switch = Fault. If a fault is present while monitoring Percent Of Throttle, the percent displayed
does not indicate actual throttle position.

NOTE – Testing Throttle Position Sensor (TPS) and Testing Idle Validation Switch (IVS) check operation
of the APS and IVS, but do not check the timing between the two functions.

Testing Throttle Position Sensor (TPS)

This test checks the TPS circuits in the accelerator pedal assembly. This test will help identify if the resistances
are within specifications and if there are any opens or shorts in the TPS, but will not verify the correct
switching of the IVS and TPS.

Table 74 Testing Throttle Position Sensor (APS)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect accelerator TPS, A to 2000 Go to next Replace the TPS/IVS
pedal from cab harness at C. to 3000 step. sensor, then
connector (267). At pedal ohms. recalibrate (refer to
side of (267) measure Accelerator/ ECM
resistance between Calibration).
terminals A and C with the
pedal in the idle position,
then with the pedal fully
depressed.
2. Off With the pedal in the TPS, B to 1500 Go to next Replace the TPS/IVS
idle position, at pedal, C. to 3000 step. switch then recalibrate
measure resistance ohms. (refer to Accelerator/
between terminals B and ECM Calibration).
C.
3. Off With the pedal in the TPS, B to 250 to Go to next Replace the TPS/IVS
full throttle position, at C. 1500 step. switch, then
pedal, measure resistance ohms, recalibrate (refer to
between terminals B and and < idle Accelerator/ ECM
C. Is reading 1000 ohms position Calibration).
less than reading at idle reading
position, and between 250 -1000
and 1500 ohms? ohms.

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Table 74 Testing Throttle Position Sensor (APS) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off At the accelerator pedal, TPS, A, B, >100K Go to next Replace the TPS/IVS
measure resistance C, D and ohms. step. switch, then
between gnd. (metal part E to gnd. recalibrate (refer to
of pedal) and terminals A, Accelerator/ ECM
B, C, D and E. Calibration).
5. Off The TPS sensor checks
good. Proceed to Testing
Idle Validation Switch (IVS
below), which checks the
idle validation portion of
the accelerator pedal.

Testing Idle Validation Switch (IVS)

This test checks the IVS circuits in the accelerator pedal assembly.

Perform Testing Throttle Position Sensor (TPS) above, before performing this test.

Table 75 Testing Idle Validation Switch (IVS)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect accelerator TPS/ IVS, F <125 Go to Replace the TPS/IVS
pedal from cab harness at to E. ohms next switch, then
connector (267). At pedal step. recalibrate. Refer
side of (267) measure to Accelerator/ ECM
resistance between Calibration.
terminals F and E with
pedal in idle position. Is it
<125 ohms?
2. Off At pedal measure TPS/ IVS, F >100K Go to Replace the TPS/IVS
resistance between to E. ohms. next switch, then recalibrate
terminals F and E while step. (refer to Accelerator/
slowly depressing the ECM Calibration).
pedal (idle to full throttle).
After approximately 10
degrees of travel, is the
resistance 100K ohms or
more?
3. Off Remove connector (252) TPS/ IVS, F >100K Go to Replace the TPS/IVS
from ECM. At pedal to D. ohms. next switch, then recalibrate
measure resistance step. (refer to Accelerator/
between terminals F and ECM Calibration).
D while the pedal is at idle
position.

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Table 75 Testing Idle Validation Switch (IVS) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off At pedal measure TPS/ IVS, F <125 Go to Replace the TPS/IVS
resistance between to D. ohms. next switch, then recalibrate
terminals F and D while step. (refer to Accelerator/
slowly depressing the ECM Calibration).
pedal (idle to full throttle).
After approximately 10
degrees of travel the
resistance should be less
than 125 ohms.
5. Off At pedal measure TPS/ IVS, >100K Go to Replace the TPS/IVS
resistance between metal metal to D, ohms next sensor, then recalibrate
part of accelerator pedal E, and F. step. (refer to Acceleration/
and terminals D, E and F. ECM Calibration).
6. Off The TPS/IVS pedal
assembly checks good.
Note that this test is not
able to check the timing
between TPS and IVS
functions.

Testing Accelerator Pedal (TPS/IVS) System for "Short or Open" Circuits

This test checks the cab and engine harness TPS/IVS circuits for opens, shorts to ground, shorts to "hot"
circuits and shorts to other circuits in the harness.

NOTE – Perform Testing Throttle Position Sensor (TPS) and Testing Idle Validation Switch (IVS) before
performing this test.

Table 76 Testing Accelerator Pedal (TPS/IVS) System for “Short or Open” Circuits
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With (267) disconnected, Go to Replace connector
disconnect connector next step. terminals if damaged.
(252) from ECM and If ECM pins are
inspect ECM connector. damaged, have
Refer to Inspecting Cummins dealer
International Engine replace ECM. Refer
Harness ECM Connector to Accelerator/
(252). ECM Calibration to
recalibrate the ECM to
TPS/IVS.

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Table 76 Testing Accelerator Pedal (TPS/IVS) System for “Short or Open” Circuits (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off At connector (252) use (252), >100K Go to Locate short to ground,
test leads and measure 99B, 99C, ohms. next step. in circuit where terminal
resistance to gnd. at 97-G, 99, resistance is less than
terminals 6, 9, 10, 11, 18 99A and 100K ohms, then
and 19 (circuits 99B, 99C, 99-G to repair.
97-G, 99, 99A and 99-G). gnd.
Do not use probes or leads
other than Cummins P/N
3822758 or the connector
could be damaged.
3. Off At connector (252) use (252), >100K Go to Locate short between
test leads and measure between ohms. next step. any circuits where
resistance between 99B, 99C, resistance between
terminals 6, 9, 11, 18 and 99, 99A, terminals is less than
19 (circuits 99B, 99C, 99, 99-G and 100K ohms, then
99A and 99-G) and all all other repair.
other terminals in (252). cir. in
conn.
4. On At connector (252) use (252), <1.5 Go to Test Locate short to
test leads and measure 99B, 99C, volts. Chart unwanted voltage
voltage to gnd. at 97-G, 99, below. source in any circuit
terminals 6, 9, 10, 11, 99A and where more than
18 and 19 (circuits 99B, 99-G to 1.5 volts is present,
99C, 97-G, 99, 99A and gnd. then repair. Refer
99-G). to Accelerator/
ECM Calibration
to recalibrate ECM/
accelerator pedal.

Testing TPS/IVS Circuits for Continuity

This test checks the individual TPS and IVS circuits (cab and engine harness) for correct resistance while
disconnected from the accelerator pedal assembly and ECM.

NOTE – Perform the preceding three tests before performing this test.

Table 77 Testing TPS/IVS Circuits for Continuity

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off At ECM connector (252) (267), 99 <5 ohms. Go to next Locate cause of
use test lead to jumper to 99A. step. out-of-specification
terminal 11 to 18 (circuit resistance in either
99 to 99A). At connector circuit 99 or 99A(5V),
(267) measure resistance then repair. Refer
between terminals B and to Accelerator/
C (circuit 99 to 99A). Do ECM Calibration to
not use probes or leads

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Table 77 Testing TPS/IVS Circuits for Continuity (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
other than Cummins recalibrate ECM/
P/N 3822758 or the accelerator pedal.
ECM connector could be
damaged.
2. Off At connector (252) use (267), < 5 ohms. Go to next Locate cause of
test lead to jumper 99-G to step. out-of-specification
terminal 11 to 19 (circuit 99. resistance in circuit
99 to 99-G). At connector 99-G, then repair.
(267) measure resistance Refer to Accelerator/
between terminals A and ECM Calibration to
B (circuit 99-G to 99). recalibrate ECM/
accelerator pedal.
3. Off At connector (252) use (267), 99 < 5 ohms. Go to next Locate cause of
test lead to jumper to 99C. step. out-of-specification
terminal 11 to 9 (circuit resistance in circuit
99 to 99C). At connector 99C, then repair.
(267) measure resistance Refer to Accelerator/
between terminals B and ECM Calibration to
D (circuit 99 to 99C). recalibrate ECM/
accelerator pedal.
4. Off At connector (252) use (267), 99 < 5 ohms. Go to next Locate cause of
test lead to jumper to 99B. step. out-of-specification
terminal 11 to 6 (circuit resistance in circuit
99 to 99B). At connector 99B, then repair.
(267) measure resistance Refer to Accelerator/
between terminals B and ECM Calibration then
E (circuit 99 to 99B). recalibrate ECM/
accelerator pedal.
5. Off At connector (252) use (267), 99 < 5 ohms. Go to next Locate cause of
test lead to jumper to 99-GA. step. out-of-specification
terminal 11 to 10 (cir. 99 resistance in circuit
to 97-G). At connector 99-GA or 97-G,
(267) measure resistance then repair. Refer
between terminals B and to Accelerator/
F (circuit 99 to 99-GA). ECM Calibration to
recalibrate ECM/
accelerator pedal.
6. Off If all four of these tests
have been performed
and defects were not
noted, the TPS and IVS
circuits check good.
If the problem is still
present, replace the
accelerator pedal. If
this does not correct the
problem, have Cummins

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Table 77 Testing TPS/IVS Circuits for Continuity (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
dealer diagnose the ECM
operation.

Accelerator/ECM Calibration

The electronic accelerator pedal assembly and the ECM must be calibrated when:

A. The pedal assembly is initially installed.

B. The pedal assembly or sensor is replaced.
C. The accelerator pedal is disconnected (at any point in the circuitry) and the key switch is placed in
the on position.

To recalibrate the accelerator pedal and ECM:

A. The vehicle key must be in the on position.

B. Depress the accelerator pedal slowly through the complete range of movement, then release.
Slowly depress and release, three times in this manner. This completes the calibration process.

3.9. LOW COOLANT SWITCH

First check for proper coolant levels. If coolant levels are not low, this test would be performed if Cummins
diagnostic codes were logged indicating a low coolant condition or other circuit fault.

This test procedure requires a VOM to check the International harness for opens, shorts to ground, or shorts
to other circuits in the International harness. The low coolant sensor has complex circuits and a VOM
should not be used to test the sensor as it may damage the circuits.

Testing Low Coolant Level Switch and Circuits

Table 78 Testing Low Coolant Level Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect 21-way (251) >100K Go to Locate short between
connector (251) from between ohms. next any circuits where
Cummins connector. 34B/(5V), step. resistance between
Disconnect (249) from 34-G, 34A terminals is less than
low coolant switch. At and 34 and all 100K ohms, then
connector (251) measure other circuits. repair.
resistance between
terminals J, K, L and M
(circuits 34B[5V], 34-G,
34A, and 34) and all other
terminals in (251).

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Table 78 Testing Low Coolant Level Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off At (251) measure (251), 34B >100K Go to Locate short to ground
resistance to ground (5V), 34-G, ohms. next in any circuit(s) where
at terminals J, K, L and M 34A, and 34 step. resistance is less
(circuits 34B[5V], 34-G, to gnd. than 100K ohms, then
34A, and 34). repair.
3. On At (251) measure voltage (251), <1.5 volts. Go to Locate short to
to ground at terminals 34B/(5V), next unwanted voltage
J, K, L and M (circuits 34-G, 34A step. source in any circuit(s)
34B[5V], 34-G, 34A and and 34 to gnd. where voltage is more
34). than 1.5V, then repair.
4. Off Measure resistance of 34, 34A, <5 ohms Go to Locate open or poor
circuits 34, 34A, 34-G 34-G, and next connection in circuit(s)
and 34B(5V) between 34B(5V) step. if resistance is more
connectors (249) and between than 5 ohms, then
(251). (249) and repair.
(251)
5. Off The low coolant switch
circuits check good. If
problem is still present,
replace low coolant
switch. If problem
persists, have Cummins
dealer diagnose ECM
operation.

3.10. POWER SUPPLY CIRCUITS TO ECM

This test checks the unswitched battery power feed to the ECM and the ECM ground circuit that is part of the
Battery Feed Harness. Check the two 15A Cummins fuses before performing this test.

NOTE – Batteries must be fully charged before performing this test.

Testing Unswitched Battery Power Circuits and ECM Ground Circuit

Table 79 Testing Unswitched Battery Power Circuits and ECM Ground Circuit
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Check ECM power Go to Correct poor
harness connector next connections.
at starter (circuit 97, step.
97A and 97-G) and
at connector (225) for
clean, tight connections.
Connections good?

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Table 79 Testing Unswitched Battery Power Circuits and ECM Ground Circuit (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off Check the two 15 amp ECM fuses. <5 ohms. Go to Locate cause of
fuses located in the next overload condition,
engine harness for open step. then correct. Replace
condition. with correct rated fuse.
3. Off Disconnect ECM power (225), 97 12 ± 1.5 Go to Locate cause of low or
connector (225) from and 97A to volts. next no voltage in circuit 97
Cummins engine harness. gnd. step. or 97A from B+ terminal
Measure voltage to gnd. or starter, then repair.
at circuits 97 and 97A.
Battery voltage present?
4. Off At connector (225) (225), 97 to 12 ± 1.5 Go to Locate open or high
measure voltage between 97-G. volts. next resistance in circuit
circuits 97 and 97-G. step. 97-G between (225)
Battery voltage present? and engine gnd. stud,
then repair.
5. On At connector (225) (225), 97 to >7 volts. Go to Locate cause of excess
measure voltage between 97-G while next voltage drop in cranking
circuits 97 and 97-G while cranking. step. circuit, then repair.
cranking engine.
6. Off Unswitched battery power
circuits and ECM ground
circuit at connector (225)
checks good.

Testing Switched Ignition Power To ECM

Table 80 Testing Switched Ignition Power To ECM

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Check 5A fuse F6-D for F6-D. <1 ohm. Go to Locate cause of overload
open condition. next condition, then repair.
step. Replace fuse.
2. On Measure voltage to 13Z to 12 ± 1.5 Go to Locate cause of no or low
ground at input circuit gnd. volts. next voltage in 13Z.
(13Z to F6-D fuse). step.

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Table 80 Testing Switched Ignition Power To ECM (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
3. Off/On Disconnect engine (251), A 12 ± 1.5 Go to Locate open in circuit
harness 21-pin ECM to gnd. volts. next 13D between fuse and
connector (251) from step. connector (251), and
Cummins harness. Turn repair.
key on, measure voltage
to gnd. at connector (251)
terminal A (circuit 13D).
4. Off Measure voltage between (251), A 12 ± 1.5 Switched Locate open in circuit
terminal A (circuit 13D and to G. volts. ignition 11-GK between engine
terminal G (circuit 11-GK). voltage ground and connector
circuit (251), then repair.
to ECM
checks
good.

3.11. SERVICE BRAKE AND CLUTCH SWITCHES

This test would be performed if the Electronic Service Tool (EST) displayed an incorrect switch position or
Cummins diagnostic codes indicate a problem may be present.

Testing Clutch Switch

Table 81 Testing Clutch Switch

STEP KEY ACTION TEST POINTS SPEC. YES-IN NO-OUT OF
SPEC. SPEC.
1. Off Disconnect clutch switch Clutch switch <2 Go to Step Check switch
connector (294) from across pigtail ohms. 3. adjustment. Go to
cab harness. With clutch terminals next step.
pedal released, measure (294).
resistance between the
pigtail terminals.
2. Off With clutch pedal Replace Adjust clutch
depressed to the bottom and adjust switch. Go to
of the free travel position clutch Step 1.
(approx. 1.7 inches or switch. Go
43 mm from pedal stop to Step 1.
plate), the u-bolt plate
should touch the switch
actuator arm. When
the clutch pedal returns
to the stop, the switch
should actuate (to closed
position) with an audible
click. Is clutch switch
adjusted properly?

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Table 81 Testing Clutch Switch (cont.)

STEP KEY ACTION TEST POINTS SPEC. YES-IN NO-OUT OF
SPEC. SPEC.
3. Off Depress clutch pedal Clutch switch >100K Go to next If switch is not
and measure resistance across pigtail ohms. step. properly adjusted,
between clutch switch terminals adjust and retest.
pigtail connector (294) (294). If switch was
terminals. properly adjusted,
replace the
switch.
4. Off Check clutch switch for Clutch switch >100K Clutch Replace the
short to gnd. With switch each pigtail to ohms. switch clutch switch,
disconnected, measure gnd. checks then adjust.
resistance to gnd. at good.
each switch terminal. Perform
Testing
Clutch
Switch
Circuits
for "Open
and Short"
Condition.

Testing Clutch Switch Circuits for “Open and Short” Condition

Perform Testing Clutch Switch before performing this test.

CAUTION – When testing at ECM connector (252), do not use probes or leads other than Cummins
test lead, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 82 Testing Clutch Switch Circuits for "Open and Short" Condition
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With clutch switch Go to Replace harness
disconnected, remove next connector terminals
ECM connector (252) step. if damaged. If ECM
from the ECM. Refer pins are damaged,
to Inspecting Navistar have Cummins dealer
Engine Harness ECM replace ECM. Refer
Connector (252) and to Accelerator/ ECM
inspect connector. ECM Calibration to recalibrate
harness connector or ECM/ accelerator pedal.
ECM pins OK?

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Table 82 Testing Clutch Switch Circuits for "Open and Short" Condition (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off Turn all CELECT cab (252), >100K Go to Locate short to gnd. in
switches to off or neutral 97AH and ohms. next circuit where resistance
position and set service 97-G to step. at terminal was less than
brake using trailer hand gnd. 100K ohms, then repair.
valve. Use test leads and
measure resistance to
gnd. at connector (252)
terminal 4 and 10 (circuit
97AH and 97-G).
3. Off With CELECT cab (252), >100K Go to Locate short between
switches still in off or 97AH and ohms. next circuits, then repair.
neutral position and 97-G and step.
service brake set, use all other
test leads and measure circuits.
resistance between
terminals 4 and 10
(circuit 97AH and 97-G)
and all other terminals in
connector (252).
4. On At connector (252), (252), <1.5 volts. The Locate short to
use test leads and 97AH and clutch unwanted voltage
measure voltage to gnd. 97-G to switch source in circuit with
at terminals 4 and 10 gnd. circuits more than 1.5 volts,
(circuit 97AH and 97-G). are free then repair. Refer
of short to Accelerator/ ECM
circuits. Calibration to recalibrate
Perform ECM/ accelerator pedal.
Testing
Clutch
Switch
Circuits
for
Continuity

Testing Clutch Switch Circuits For Continuity

CAUTION – When testing at ECM connector (252), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

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Table 83 Testing Clutch Switch Circuits For Continuity

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off At ECM connector (252) use (294), <5 ohms Go to Locate open or
test lead to jumper terminal 97AH to next poor connection in
4 (circuit 97AH) to ground. gnd. step. circuit 97AH between
At clutch switch connector connectors (252) and
(294) measure resistance of (294), then repair.
97AH to ground.
2. Off At ECM connector (252) use (294), <5 ohms. Go to Locate open or poor
test lead to jumper terminal 97AH to next connection in circuit
4 to 10 (circuit 97AH to 97-GF. step. 97-GH, 97-GA or 97-G
97-G). At clutch switch between connectors
connector (294) measure (252) and (294), then
resistance between circuits repair.
97AH and 97-GF.
3. Off The clutch switch circuits
and switch check good.

Testing Service Brake Switch (141)

Table 84 Testing Service Brake Switch (141)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (141) Brake <2 Go to next Replace the brake
from brake switch. With pressure ohms. step. switch.
brakes released, measure switch
resistance across switch across
terminals. Switch should terminals.
be closed.
2. Off Apply service brakes Brake >100K Go to next Replace the brake
and measure resistance pressure ohms. step. switch.
across the brake pressure switch
switch. Switch should be across
open. NOTE: Sufficient terminals.
air pressure must be
present to apply service
brakes for this test step.
3. Off Measure resistance to Brake >100K Reconnect Replace the brake
gnd. at both brake switch pressure ohms. (141) to switch.
terminals with service switch both brake
brakes applied, and with terminals to switch.
brakes released. Both gnd. Perform
should be isolated from Testing
ground at all times. Service
Brake
Switch
Circuits
for "Open

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Table 84 Testing Service Brake Switch (141) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
and Short"
Condition

Testing Service Brake Switch Circuits for "Open and Short" Condition

Perform Testing Service Brake Switch (141) before performing this test.

CAUTION – When testing at ECM connector (252), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 85 Testing Service Brake Switch Circuits for "Open and Short" Condition
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With connector (141) Go to Replace harness
disconnected from brake next step. connector terminals
switch, remove connector if damaged. If ECM
(252) from the ECM. Refer pins damaged, have
to Inspecting International Cummins dealer replace
Engine Harness ECM ECM.
Connector (252) to
inspect connector. ECM
connector and ECM pins
OK?
2. Off Turn all CELECT cab (252), >100K Go to Locate short to ground. in
switches to off or neutral 97AL and ohms. next step. circuit where resistance
position and disconnect 97-G to at terminal was less than
clutch switch. Use test gnd. 100K ohms, then repair.
leads and measure
resistance to gnd. at
connector (252) terminals
13 and 10 (circuits 97AL
and 97-G).
3. Off Use test leads and (252), >100K Go to Locate short between
measure resistance 97AL to ohms. next step. any circuit where
between terminal 13 97-G and resistance between
and 10 (circuits 97AL all other terminals is less than
and 97-G) and all other circuits. 100K ohms, then repair.
terminals in connector
(252).
4. On At connector (252), use (252), <1.5 The Locate short to unwanted
test leads and measure 97AL and volts. brake voltage source in circuit
voltage to ground at switch

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Table 85 Testing Service Brake Switch Circuits for "Open and Short" Condition (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
terminals 13 and 10 97-G to circuits with more than 1.5 volts,
(circuits 97AL and 97-G). gnd. are free then repair.
of short
circuits.
Perform
Testing
Service
Brake
Switch
Circuits
for
Continuity.

Testing Service Brake Switch Circuits for Continuity

CAUTION – When testing at ECM connector (252), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 86 Testing Service Brake Switch Circuits for Continuity

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off At ECM connector (252) (141), <5 ohms. Go to Locate open or
use test lead to jumper 97AL to next poor connection in
terminal 13 (cir. 97L) gnd. step. circuit 97AL between
to gnd. At brake switch connectors (252) and
connector (141) measure (141), then repair.
resistance to ground at
circuit 97AL.
2. Off At ECM connector (252) (141), <5 ohms. Go to Locate open or poor
use test lead to jumper 97AL to next connection in circuit
terminal 13 to terminal 10 97-GF. step. 97-GF, 97-GA, or 97-G
(circuits 97AL to 97-G). between connectors
At brake switch connector (252) and (141), then
(141) measure resistance repair.
between circuits 97AL and
97-GF.
3. Off The service brake switch
circuits and switch check
good.

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3.12. ENGINE BRAKE

In the event the engine brake fails to operate, the following test chart provides a systematic series of steps
to check the switches and circuits that are installed by International.

Testing Engine Brake Components and Circuits

Table 87 Testing Engine Brake Components and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove engine brake (434), <1 ohm. Go to next Locate open or
on/off switch from 24-G to step. poor connection in
connector (434). Measure gnd. circuit 24-G, 97-GA
resistance to ground at or 97-G, then repair.
connector (434), circuit
24-G.
2. Off With on/off switch removed, Go to next Replace the switch.
refer to Testing Engine step.
Brake Switches and use
ohmmeter to check switch.
Switch good?
3. Off Remove connector (433) 24AD <5 ohms. Go to next Locate open or poor
from selector switch. between step. connection in circuit
Measure resistance of (434) and 24AD between
circuit 24AD between (433). connectors (434)
connectors (434) and and (433), then
(433). repair.
4. Off Refer to Testing Engine Go to next Replace the switch.
Brake Switches and test step.
the selector switch. Switch
good?
5. Off Re-install connector (434) Go to next
to engine brake on/off step.
switch and place in on
position. Re-install conn.
(433) to engine brake
switch and place in position
3. Disconnect 21-way
conn. (252) from engine
harness.
6. On At connector (252) (252), <1 ohm. Engine Locate open or
measure resistance from 24AE and brake poor connection
pin 5 and 28 to ground 24AF to circuits and in circuit 24AE
(circuit 24AE and 24AF to gnd. components or 24AF between
ground). check connectors (433)
good. and (252), then
repair.

Testing Engine Brake Switches

1. Testing Engine Brake On/Off Switch

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 293

a. With switch in on position, resistance between terminals 5 and 6 and between 2 and 3 should be
less than 5 ohms.
b. With switch in off position, resistance should be 100K ohms or more.
c. To test the LED in the switch, connect B+ test lead to terminal 7 and ground terminal 8. LEDs should
illuminate.

2. Testing Engine Brake Selector Switch With N14E Engine.

a. With switch in 3 position, resistance between terminals 2 and 3 and 6 should be less than 5 ohms.
b. With switch in 1 position, resistance between terminals 2 and 3 should be less than 5 ohms.
c. With switch in 2 position, resistance between terminals 2 and 6 should be less than 5 ohms.
d. To test the LED in the switch, connect B+ test lead to terminal 7 and ground terminal 8. LEDs should
illuminate.

3.13. ATA DATA LINK CONNECTOR (137) AND SPEEDOMETER/TACHOMETER INPUT

CIRCUITS
This following series of tests provide charts for testing: [1] The Data Link circuits between the ECM and ATA
Data Link connector (137) and the speedometer/tachometer connector (421). [2] The power and ground
circuits to the ATA Data Link connector (137).

Testing Diagnostic Connector Power and Ground Circuits

Table 88 Testing Diagnostic Connector Power and Ground Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove and check F5-D. <1 ohm Go to next Locate cause of
20A fuse F5-D for open step. overload condition,
condition. then repair. Replace
5A fuse.
2. On Re-install fuse. At (137), 12 ± 1.5 Go to next Locate cause of no or
connector (137) measure 97DL to volts. step. low voltage in circuit
voltage to at terminal C gnd. 97DL from fuse F9-C,
(circuit 97DL) to gnd. then repair.
3. On At connector (137) (137), 12 ± 1.5 Go to next Locate open or poor
measure voltage between 97DL to volts. step. connection in circuit
terminals C and E (circuits 11-GR. 11-GR between
97DL and 11-GR). connector (137) and
G1 ground adapter
(453), then repair.
4. On The power and gnd.
circuits to the ATA data
link connector (137) check
good.

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Testing Data Link Circuits Between Diagnostic Connector, ECM and Speedometer/Tachometer Unit

CAUTION – When testing at ECM connector (252), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 89 Testing Data Link Circuits Between Diagnostic Connector, ECM and Speedometer/Tachometer
Unit
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect ECM Go to Replace harness
connector (252) from next connector terminals
the ECM. Refer to step. if damaged. If ECM
Inspecting International pins are damaged,
Engine Harness ECM have Cummins
Connector (252) and dealer replace ECM.
inspect connector. ECM Refer to Accelerator/
harness connector OK? ECM Calibration to
recalibrate ECM/
accelerator pedal.
2. Off Disconnect connector (252), >100K Go to Locate short circuit
(421) from speedometer/ 98B(-) and ohms. next to ground in circuit
tachometer unit and 98(+) to step. where resistance is
if additional devices gnd. less than 100K ohms,
have been connected to then repair.
(514) and (515) data link
connectors, they must
be disconnected. At
connector (252), using
test leads, measure
resistance to gnd. at
terminals 8 and 27 (circuit
98B[-] and 98[+]).
3. On At connector (252) use (252), >100K Go to Locate short between
test leads and measure 98B(-) and ohms. next circuits where
resistance between 98(+) and step. resistance between
terminals 8 and 27 (circuit all other terminals is less than
98B[-] and 98[+]) and circuits in 100K ohms, then
all other terminals in conn. repair.
connector.
4. On At connector (252) use (252), <1.5 volts Go to Locate short to
test leads and measure 98B(-) and next unwanted voltage
voltage to gnd. at 98(+) to step. source in circuit where
terminals 8 and 27 gnd. more than 1.5 volts
(circuits 97B[-] and 98[+]). is present at terminal,
then repair.

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Table 89 Testing Data Link Circuits Between Diagnostic Connector, ECM and Speedometer/Tachometer
Unit (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
5. Off At connector (252) use (137) , <5 ohms. Go to Locate open or poor
test lead to jumper 98C(-) to next connection in circuit
terminal 8 (cir. 98B[-]) gnd. step. 98B(-) or 98C(-)
to gnd. At connector (137) between connectors
measure resistance to (252) and (137), then
gnd. at terminal B (cir. repair.
98C[-]).
6. Off With connector (252) (421), 47/ <5 ohms. Go to Locate open or poor
terminal 8 (cir. 98B[-]) 48(-) to gnd. next connection in circuit
still jumpered to gnd., at step. 47/48(-) between
connector (421) measure connectors (515) and
resistance to gnd. at (421), then repair.
circuit 47/48(-).
7. Off At connector (252) use (137), <5 ohms. Go to Locate open or poor
test lead to jumper 98A(+) to next connection in circuit
terminal 27 (cir. 98[+]) gnd. step. 98(+)/(98A+) between
to gnd. At connector connectors (252) and
(137) measure resistance (137), then repair.
terminal A (cir. 98A[+]) to
ground.
8. Off With connector (252) (421), 47/ <5 ohms. Go to Locate open or poor
terminal 27 (cir. 98[+]) 48(+) to next connection in circuit
still jumpered to gnd., at gnd. step. 47/48(+) between
connector (421) measure connectors (514) and
resistance to gnd. at (421), then repair.
circuit 47/48(+).
9. Off The data link circuits
between ECM connector
(252), diagnostic
connector (137) and
speedometer/ tachometer
connector (421) test good.

3.14. DIAGNOSTIC SWITCHES

The diagnostic On/Off and Idle/Diagnostic switches can be checked with CompulinkTM EZ-Tech or Pro Link
9000 in the switch monitoring mode. If the switches do not operate properly, perform the following test.

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Testing Diagnostic On/Off Switch and Circuit

Table 90 Testing Diagnostic On/Off Switch and Circuit

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (241) Across <5 ohms. Go to Replace the switch.
from On/Off switch. With terminals next
switch in on position, 5 and 6. step.
measure resistance
between terminals 5 and
6.
2. Off With switch in off position, Across >100K Go to Replace the switch.
measure resistance terminals ohms. next
between terminals 5 and 5 and 6. step.
6.
3. Off To test the LED in the Go to Replace the switch.
switch, connect B+ test next
lead to terminal 7 and step.
connect terminal 8 to gnd.
Does LED illuminate?
4. Off Remove ECM connector Go to Replace harness
(252) from the ECM. Refer next connector terminals
to Inspecting International step. if damaged. If ECM
Engine harness ECM pins are damaged,
Connector (252) and have Cummins
inspect connector. ECM dealer replace ECM.
harness connector and Refer to Accelerator/
ECM pins OK? ECM Calibration to
recalibrate ECM/
accelerator pedal.
5. Off Disconnect connector (251), >100K Go to Locate short to gnd.
(251) measure resistance 97AM to ohms. next in circuit 97AM, then
from terminal V (cir. 97AM) gnd. step. repair.
to gnd.
6. Off At connector (252) (252), >100K Go to Locate short to ground
measure resistance from 97-G to ohms. next in circuit 97-G or
terminal 10 (cir. 97-G) to gnd. step. 97-GA, then repair.
ground.
7. Off With all CELECT switches (252), >100K Go to Locate short between
in off or neutral position, 97AM to ohms. next circuits where
service brakes set using all other step. resistance between
trailer hand control circuits. terminals is less than
valve, and clutch switch 100K ohms, then
disconnected, measure repair.
resistance between
terminal V (cir. 97AM)
and all other terminals in
(251).

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Table 90 Testing Diagnostic On/Off Switch and Circuit (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
8. Off At connector (251), use (251), <5 ohms. Go to Locate open or
test lead and jumper 97AM to next poor connection in
terminal V (cir. 97AM) to gnd. step. circuit 97AM between
gnd. At connector (241) connectors (241) and
measure resistance to (251), then repair.
gnd. at circuit 97AM.
9. Off At connector (252), use (241), <5 ohms. Go to Locate open or poor
test lead and jumper 97-GE to next connection in circuit
terminal 10 (cir. 97-G) to gnd. step. 97-GE, 97-GA or 97-G
gnd. At connector (241) between connectors
measure resistance to (241) and (252), then
gnd. at circuit 97-GE. repair.
10. Off The diagnostic On/Off
switch and circuits check
good.

Testing Idle/Diagnostic Switch (243) and Circuits

Table 91 Testing Idle/Diagnostic Switch (243) and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (243) Across <5 ohms. Go to Replace the switch.
from idle/ diagnostic switch switch term. next
and test the switch. With 2 and 3. step.
switch in INC position
measure resistance
between terminals 2 and 3.
2. Off With switch in neutral Across > 100K Go to Replace the switch.
position measure switch term. ohms. next
resistance between 1, 2 and 3. step.
terminals 1, 2 and 3.
3. Off With switch in DEC position Across sw. <5 ohms. Go to Replace the switch.
measure resistance term 1 and next
between terminals 1 and 2. 2. step.
4. Off To test the LED in the Go to Replace the switch.
switch, connect B+ test next
lead to terminal 7 and step.
connect terminal 8 to gnd.
Does LED illuminate?

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Table 91 Testing Idle/Diagnostic Switch (243) and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
5. Off Disconnect ECM connector Go to Replace harness
(252) from the ECM next connector terminals
and inspect. Refer to step. if damaged. If ECM
Inspecting International pins are damaged,
Engine Harness ECM have Cummins
Connector (252). ECM dealer replace ECM.
harness connector or ECM Refer to Accelerator/
pins OK? ECM Calibration to
recalibrate ECM/
accelerator pedal.
6. Off At connector (252) use (252), 97-G, >100K Go to Locate short to gnd. in
test leads and measure 97AV and ohms. next circuit where terminal
resistance to gnd. at 97AU to gnd. step. resistance is less
terminals 10, 14, and 23 than 100K ohms, then
(circuits 97-G, 97AV and repair.
97AU).
7. Off At connector (252) measure (252), 97AV >100K Go to Locate short circuit
resistance between and 97AU ohms. next between any circuit
terminals 14 and 23 to all other step. where resistance
(cir. 97AV and 97AU) circuits. between terminals is
and all other terminals in less than 100K ohms,
connector. then repair.
8. On At connector (252) measure (252), 97AV <1.5 Go to Locate short to
voltage to gnd. at terminals and 97AU to volts. next unwanted voltage
14 and 23 (circuits 97AV gnd. step. source, then repair.
and 97AU).
9. Off At connector (252) use test (243), 97AV <5 ohms. Go to Locate open or
lead to jumper terminal 14 to gnd. next poor connection in
(circuit 97AV) to gnd. At step. circuit 97AV between
connector (243) measure connectors (243) and
resistance to gnd. at circuit (252), then repair.
97AV.
10. Off At connector (252) use test (243), 97AU <5 ohms. Go to Locate open or
lead to jumper terminal to gnd. next poor connection in
23 (cir. 97AU) to gnd. At step. circuit 97AU between
connector (243) measure connectors (243) and
resistance to gnd. at circuit (252), then repair.
97AU.

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Table 91 Testing Idle/Diagnostic Switch (243) and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
11. Off At connector (252) use test (243), <5 ohms. Go to Locate open or
lead to jumper terminal 97-GD to next poor connection in
10 (cir. 97-G) to gnd. At gnd. step. circuit 97-GD, 97-GA,
connector (243) measure or 97-G between
resistance to gnd. at circuit connectors (243) and
97-GD. (252), then repair.
12. Off The idle/diagnostic switch
and circuits check good.

3.15. CRUISE CONTROL

When monitoring switches with a Electronic Service Tool, the cruise On/Off switch will indicate On or Off.
The Set/Resume switch will indicate either Set or Res, depending on the switch position. If the switch is
not operable, the screen will be blank.

Testing Cruise Control On/Off Switch and Circuits

CAUTION – When testing at ECM connector (252), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 92 Testing Cruise Control On/Off Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (435) Across <5 ohms. Go to Replace the switch.
from cruise On/Off switch. terminals next
With switch in on position, 5 and 6. step.
measure resistance
between terminals 5 and
6.
2. Off With switch in off position, Across > 100K Go to Replace the switch.
measure resistance terminals ohms. next
between terminals 5 and 5 and 6. step.
6.
3. Off To test the LED in the Go to Replace the switch.
switch, connect B+ test next
lead to terminal 7 and step.
connect terminal 8 to gnd.
Does LED illuminate?

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Table 92 Testing Cruise Control On/Off Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off Remove ECM connector Go to Replace harness
(252) from the ECM and next connector terminals
inspect (refer to Inspecting step. if damaged. If ECM
International Engine pins are damaged,
Harness ECM Connector have Cummins
(252), ECM harness dealer replace ECM.
connector and ECM pins Refer to Accelerator/
OK? ECM Calibration to
recalibrate ECM/
accelerator pedal.
5. Off At ECM connector (252) (252), >100K Go to Locate short to gnd.
use test leads and 97AE and ohms. next in circuit with less
measure resistance to 97-G to step. than 100K ohms, then
gnd. at terminals 2 and 10 gnd. repair.
(circuits [97AE and 97-G]).
6. Off At connector (252) (252), 2 to >100K Go to Locate short between
measure resistance all other ohms. next circuit 97AE and
between terminal 2 and terminals. step. any circuit where
all other terminals in resistance between
connector. terminals is less than
100K ohms, then
repair.
7. On At connector (252) (252), <1.5 Go to Locate short between
measure voltage from 97AE to volts. next circuit 97AE and
terminal 2 (circuit 97AE) to gnd. step. unwanted voltage
ground. source, then repair.
8. Off At connector (252) use test (435), <5 ohms. Go to Locate open or
lead to jumper terminal 2 97AE to next poor connection in
(circuit 97AE) to gnd. At gnd. step. circuit 97AE between
connector (435) measure connectors (252) and
resistance to gnd. at circuit (435), then repair.
97AE.
9. Off At connector (252) use test (435), <5 ohms. Go to Locate open or poor
lead to jumper terminal 10 97-GC to next connection in circuit
(circuit 97-G) to gnd. At gnd. step. 97-GC, 97-GA or
connector (435) measure 97-G, then repair.
resistance to gnd. at circuit
97-GC.
10. Off The cruise on/off switch
and circuits check good.

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 301

Testing Cruise Set/Resume Switch and Circuits

CAUTION – When testing at ECM connector (252), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 93 Testing Cruise Set/Resume Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (436) Between <5 Go to Replace the switch.
from cruise set/resume switch term. ohms. next
switch. With switch in 2 and 3. step.
set position, measure
resistance between
terminals 2 and 3.
2. Off With switch in neutral Between sw. >100K Go to Replace the switch.
position, measure term. 1, 2 ohms. next
resistance between and 3. step.
terminals 1, 2 and 3.
3. Off With switch in resume Between sw. <5 Go to Replace the switch.
position, measure term 1 and 2. ohms. next
resistance between step.
terminals 1 and 2.
4. Off To test the LED in the Go to Replace the switch.
switch, connect B+ test next
lead to terminal 7 and step.
connect terminal 8 to gnd.
Does LED illuminate?
5. Off Remove ECM connector Go to Replace harness
(252) from the ECM next connector terminals
and inspect. Refer to step. if damaged. If ECM
Inspecting International pins are damaged,
Engine Harness ECM have Cummins
Connector (252). ECM dealer replace ECM.
harness connector and Refer to Accelerator/
ECM pins OK? ECM Calibration to
recalibrate ECM/
accelerator pedal.
6. Off At ECM connector (252) (252), 97AB, >100K Go to Locate short to gnd. in
use test leads and 97AA and ohms. next circuit with less than
measure resistance to 97-G to gnd. step. 100K ohms, then repair.
gnd. at terminals 12, 22
and 10 (cir. 97AB, 97AA
and 97-G).

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Table 93 Testing Cruise Set/Resume Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
7. Off At connector (252) (252), >100K Go to Locate short between
measure resistance between ohms. next any circuits where
between terminal 12 97AB and step. resistance between
and 22 (circuits 97AB 97AA, and terminals is less than
and 97AA), and all other all others. 100K ohms, then repair.
terminals in the connector.
8. On At connector (252) (252), 97AB <1.5 Go to Locate short to
measure voltage to gnd. and 97AA to volts. next unwanted voltage
at terminals 12 and 22 gnd. step. source in circuit 97AA
(circuits 97AB and 97AA). or 97AB, then repair.
9. Off At connector (252) use test (436), 97AB <5 Go to Locate open or
lead to jumper terminal to gnd. ohms. next poor connection in
12 (cir. 97AB) to gnd. At step. circuit 97AB between
connector (436) measure connectors (252) and
resistance to gnd. at circuit (436), then repair.
97AB.
10. Off At connector (252) use test (436), 97-GB <5 Go to Locate open or poor
lead to jumper terminal to gnd. ohms. next connection in circuits
10 (cir. 97-G) to gnd. At step. 97-GB, 97-GA or 97-G,
connector (436) measure then repair.
resistance to gnd. at circuit
97-GB.
11. Off At connector (252) use test (436) , 97AA <5 Go to Locate open or
lead to jumper terminal to gnd. ohms. next poor connection in
22 (cir. 97AA) to gnd. At step. circuit 97AA between
connector (436) measure connectors (252) and
resistance to gnd. at circuit (436), then repair.
97AA.
12. Off The cruise set/resume
switch and circuits check
good.

3.16. VEHICLE SPEED SENSOR

When monitoring engine functions with an EST, if the vehicle is moving the miles-per-hour will display as
MPH=XXX (actual vehicle speed if operating properly). To test the sensor and circuits to the ECM, use
the following test charts.

Inspecting and Adjusting the Vehicle Speed Sensor (VSS)

1. Disconnect engine harness connector (250) from the sensor. Loosen the locknut and remove the sensor.
The harness connector and sensor should be free of damage or corrosion. Remove any metal shavings or
debris from the sensor.

2. To install the adjustable sensor, turn in until the sensor contacts the transmission speedometer gear, then
back out one full turn. Tighten locknut to 15 ft-lbs. (20.3 N•m). This assures that the sensor is adjusted
properly for the next test.

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 303

Testing Vehicle Speed Sensor

Construct test leads using terminals (International Part No. 1680205C1), short length of 16 gauge wire
and alligator clips.

WARNING – A jack must never be used alone to support vehicle. The jack may lower and
serious injury could result. Always support vehicle with floor jacks. Always block wheels to prevent
vehicle from moving.

WARNING – EXTREME CAUTION should be used to prevent personal injury resulting from
contact with rotating vehicle wheels when connecting test leads.

Table 94 Testing Vehicle Speed Sensor

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Inspect VSS for damage Go to next
and proper adjustment step.
before performing this
test. Refer to Inspecting
and Adjusting the Vehicle
Speed Sensor (VSS)
above.
2. Off Disconnect engine VSS, 600 Go to next Replace the vehicle
harness (250) from VSS term. 1 to 800 step. speed sensor (VSS).
and use test leads to to 2. ohms for
measure resistance adjustable
between terminal 1 and 2 sensor.
of sensor connector.
1500 to
3500 for
non-adjustable
sensor.
3. Off Measure resistance to VSS, >100K Go to next Replace the vehicle
gnd. at both sensor term. 1 ohms. step. speed sensor (VSS).
terminals. and 2 to
gnd.
4. Off Block front wheels and Go to next
place rear axles on floor step.
stands.

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Table 94 Testing Vehicle Speed Sensor (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
5. Off Use AC voltmeter with Go to next
sufficient length leads to step.
avoid personal contact
with rotating vehicle
wheels during test.
Connect meter leads
to test leads.
6. Off Run engine at idle speed, VSS, >2.0 volts VSS Replace the VSS (refer
with transmission in high across AC. checks to Inspecting And
gear. Measure voltage terminals. good. Adjusting the Vehicle
across the two sensor Speed Sensor above).
terminals. NOTE: Improper
sensor adjustment
will cause low, erratic
or no output.

Testing Vehicle Speed Sensor Circuits To ECM

To check circuits between the ECM and the speedometer/tachometer unit, refer to ATA Data Link Connector
(137) and Speedometer/Tachometer Input Circuits.

CAUTION – When testing at ECM connector (252), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 95 Testing Vehicle Speed Sensor Circuits To ECM

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (250) Go to next Replace harness
from vehicle speed sensor. step. connector terminals
Remove ECM connector if damaged. If ECM
(252) from the ECM and pins are damaged,
inspect (refer to Inspecting have Cummins
International Engine dealer replace ECM.
Harness ECM Connector Refer to Accelerator/
(252). ECM harness ECM Calibration to
connector and ECM pins recalibrate ECM/
OK? accelerator pedal.
2. Off At connector (252), use (252), >100K Go to next Locate short to gnd.
test leads and measure 97AJ and ohms. step. in circuit with less
resistance to gnd. at 97AK to than 100K ohms, then
terminals 3 and 7 (cir. gnd. repair.
97AJ and 97AK).

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Table 95 Testing Vehicle Speed Sensor Circuits To ECM (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
3. Off At connector (252), (252), >100K Go to next Locate short circuit
measure resistance 97AJ and ohms step. between circuits where
between terminals 3 and 97AK and resistance between
7 (cir. 97AJ and 97AK), all others. terminals is less than
and all other terminals in 100K ohms, then
connector. repair.
4. On At connector (252), (252), <1.5 Go to next Locate short to
measure voltage at 97AJ and volts. step. unwanted voltage
terminals 3 and 7 (circuits 97AK to source in circuit where
97AJ and 97AK) to gnd. gnd. voltage at terminal is
more than 1.5 volts,
then repair.
5. Off At connector (252) use (250), <5 ohms. Go to next Locate open or
test leads and jumper 97AJ to step. poor connection in
terminal 3 (circuit 97AJ) to gnd. circuit 97AJ between
gnd. At connector (250) connectors (252) and
measure resistance to (250), then repair.
gnd. at circuit 97AJ.
6. Off At connector (252) use (250), <5 ohms. Go to next Locate open or
test leads and jumper 97AK to step. poor connection in
terminal 7 (circuit 97AK) to gnd. circuit 97AK between
gnd. At connector (250) connectors (252) and
measure resistance to (250), then repair.
gnd. at circuit 97AK.
7. Off The vehicle speed sensor
circuits between the
sensor and ECM check
good.

4. COMPONENT LOCATIONS
B1 Battery Stud.. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . . . . . Power Distribution Panel
(1) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Left Side of Engine Cowl
(2) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Above Connector 3
(3) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Below Connector 2
(72) Ether Start Connector. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Front End Harness, At Lower Left of Radiator
(94) Back-up Light Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . On Transmission
(137) 6-Way Data Link Connector. . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(141) Service Brake Switch/Cruise Switch. . . . . . . . .. . . . . . Dash Panel, Left Side, Engine Side
(216) ECM Power Connector. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Start Motor
(227) Fan Solenoid.. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .. . . . . . At Front of Engine
(228) Refrigerant Pressure Switch. . . . . . . . . . . . . . . . . .. . . . . . On A/C Compressor
(229) Engine Oil Temp Sender. .. . .. .. . .. . .. .. . .. . .. .. . . . . . Left Side of Engine
(230) Cab Overlay to Elect. Eng. Harn.. . . . . . . . . . . .. . . . . . Right Instrument Panel
(235) Transmission Oil Temp (Inline). . .. . . . .. . . .. . . .. . . . . . On Front of Transmission
(249) Low Coolant Level Switch. . . . . . . . . . . . . . . . . . . . .. . . . . . To Engine Harness

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306 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM

(250) Vehicle Speed Sensor. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . On Transmission

(251) CELECT 9-Way ECM Connector. . . . . . . . . . . . .. . . . . . At Engine Harness near ECM
(252) Electronic Control Module ECM. . . . . . . . . . . . . .. . . . . . At ECM
(267) Accelerator Pedal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . To Cab Overlay
(294) Clutch Switch Connector. . . . . . . . . . . . . . . . . . . . . .. . . . . . Near Clutch Switch
(403) J1922 Data Link. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Dash Panel Right Side
(420) Right Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Gauge Cluster
(421) Speedo./Tach. Module. . . .. . . .. . .. . . .. . . .. . . .. .. . . . . . Behind Speedo./Tach. Gauge
(422) Speedo./Tach. Module. . . .. . . .. . .. . . .. . . .. . . .. .. . . . . . Behind Speedo./Tach. Gauge
(423) Left Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Left Gauge Cluster
(424) Left Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Left Gauge Cluster
(514) Data Link - Positive. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel/Behind Cluster
(515) Data Link - Negative. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel/Behind Cluster

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 307

Figure 101 Engine Wiring, Cab

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308 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM

1. DASH PANEL (VIEWED FROM INSIDE ENGINE COMPARTMENT)

2. (141) BRAKE SWITCH
3. (640) STOP LIGHT SWITCH
4. (190) ELECTRONIC ENGINE CONNECTOR
5. RIGHT HAND DASH PANEL GROUND STUD
6. (3) ENGINE CONNECTOR
7. (2) CHASSIS HARNESS CONNECTOR
8. POWER DISTRIBUTION PANEL
9. SWITCHES
10. RIGHT GAUGE CLUSTER
11. SPEEDOMETER / TACHOMETER CLUSTER
12. LEFT GAUGE CLUSTER
13. (514) DATA LINK CONNECTOR
14. (515) DATA LINK CONNECTOR
15. (137) DATA LINK
16. CLUTCH SWITCH
17. FRONT END HARNESS CONNECTOR
18. THROTTLE PEDAL
19. (294) CLUTCH SWITCH CONNECTOR
20. (267) THROTTLE PEDAL CONNECTOR

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 309

Figure 102 Engine Wiring, Dash Panel

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310 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM

1. (190) ELECTRONIC ENGINE CONNECTOR

2. RH DASH PANEL GROUND STUD
3. (2) CAB/ENGINE HARNESS CONNECTOR
4. MEGAFUSE
5. START MAGNETIC SWITCH
6. CIRCUIT 14A TO (B1) BATTERY STUD
7. CIRCUIT 17C
8. CIRCUIT 17B
9. CIRCUIT 14
10. (249) LOW COOLANT SENDER
11. TO ENGINE HARNESS

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 311

Figure 103 Engine Wiring

1. STARTER MOTOR
2. CIRCUIT 11-GA
3. ECM
4. CIRCUIT 11-GS
5. ENGINE GROUND STUD
6. (411) J1922 DATA LINK
7. CIRCUIT 77C TO A/C COMPRESSOR CLUTCH
8. (228) A/C PRESSURE SWITCH CIRCUITS 23A AND 23-GB
9. TO TRANSMISSION
10. CIRCUIT 21A THERMOSTATIC SWITCH CONNECTOR

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Figure 104 Engine Wiring

1. ALTERNATOR
2. TO ENGINE WIRING AT DASH (9400 & 9900)
3. TO ENGINE WIRING AT DASH (9100 & 9200)
4. TO TRANSMISSION

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Figure 105 Engine Wiring, Transmission Effects

1. (250) VEHICLE SPEED SENSOR
2. TO ENGINE WIRING
3. (235) TRANSMISSION OIL TEMPERATURE CONNECTOR
4. (94) BACK-UP LIGHT SWITCH

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Figure 106 Engine Wiring, Starter Motor

1. CIRCUIT 11-GL
2. CIRCUIT 11-GS
3. ENGINE GROUND
4. CIRCUIT 97-G
5. ENGINE HARNESS
6. CIRCUIT 97 & 97A
7. FUSIBLE LINK CIRCUIT 14
8. CIRCUIT 17C

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 315

Figure 107 Engine Wiring, Electronic Control Module

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316 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM

1. CUMMINS ENGINE HARNESS

2. (251) INTERNATIONAL ENGINE HARNESS ECM CONNNECTOR
3. (251) INTERNATIONAL 21-WAY CONNECTOR
4. CIRCUIT 11-GS
5. ELECTRONIC CONTROL CONNECTOR
6. (252) ECM CONNECTOR
7. INLINE FUSES
8. CIRCUIT 97
9. CIRCUIT 97A

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 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM 317

Figure 108 Engine Wiring, Alternator Effects (N14)

1. CIRCUIT 11-GL
2. ENGINE HARNESS
3. CIRCUIT 2
4. CIRCUIT 11-GS
5. ENGINE HARNESS
6. CIRCUIT 2
7. ENGINE HARNESS
8. CIRCUIT 11-GA
9. CIRCUIT 2

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318 8 CUMMINS N14 ELECTRONIC ENGINE SYSTEM

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 9 CUMMINS ISM AND AHD ENGINE SYSTEM 319

Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .321

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .322
2.1. ECM POWER. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .322
2.2. ATA DATA LINK CONNECTOR. . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .322
2.3. DIAGNOSTIC ON/OFF SWITCH. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .323
2.4. IDLE/DIAGNOSTIC SWITCH. .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .323
2.5. ELECTRONIC ACCELERATOR PEDAL ASSEMBLY. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .323
2.6. COOLANT LEVEL SWITCH.. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .324
2.7. CRUISE CONTROL. .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .324
2.8. BRAKE SWITCH . . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .325
2.9. CLUTCH SWITCH.. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .325
2.10. VEHICLE SPEED SENSOR. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .326
2.11. ENGINE BRAKE SWITCHES. . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . .326
2.12. GAUGES AND WARNING LIGHTS. . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .326
2.13. J1939 DATA LINK. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . .326

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .326
3.1. ONBOARD DIAGNOSTICS WITH ENGINE RUNNING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .327
3.2. PERFORMING A DIAGNOSTIC CHECK WITH THE ENGINE OFF. . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .328
3.3. CUMMINS ELECTRONIC SERVICE TOOL.. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .329
3.4. EZ-TECH OR PRO-LINK ELECTRONIC SERVICE TOOL (EST). .. . . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .329
3.5. RELAYS.. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. .329
3.6. TESTING RELAY. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .329
3.7. ACCELERATOR PEDAL TPS/IVS.. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .330
Testing Throttle Position Sensor (TPS). . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .330
Testing Idle Validation Switch (IVS).. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .331
Testing Accelerator Pedal (TPS/IVS) System for “Short or Open” Circuits. . . . . . . . . . . . . .332
Testing TPS/IVS Circuits for Continuity. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .333
Accelerator/ECM Calibration.. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .335
3.8. LOW COOLANT SWITCH. .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .335
Testing Low Coolant Level Switch And Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .335
3.9. POWER SUPPLY CIRCUITS TO ECM.. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .336
Testing Unswitched Battery Power Circuits And ECM Ground Circuit. . . . . . . . . . . . . . . . . . .336
Testing Switched Ignition Power To ECM . .. . .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. . .. .. .. . .. .. .. . .. .. .337
3.10. SERVICE BRAKE AND CLUTCH SWITCHES. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .338
Testing Clutch Switch.. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .338
Testing Clutch Switch Circuits for "Open and Short" Condition. . . .. . . . . . . .. . . . . . . .. . . . . . .338
Testing Clutch Switch Circuits For Continuity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .340
Testing Service Brake Switch (141). . .. .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. .340
Testing Service Brake Switch Circuits for "Open and Short" Condition.. .. . .. .. . .. .. . .. .341
Testing Service Brake Switch Circuits for Continuity. .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .342
3.11. ENGINE BRAKE.. . .. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. .343
Testing Engine Brake Components And Circuits. .. . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . .343
Testing Engine Brake Switches. . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .344
3.12. ATA DATA LINK CONNECTOR (137) AND SPEEDOMETER/TACHOMETER INPUT
CIRCUITS. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .344

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Testing Diagnostic Connector Power and Ground Circuits. . . . .. . . . . . .. . . . . .. . . . . .. . . . . .. . .345

Testing Data Link Circuits Between Diagnostic Connector, ECM and
Speedometer/Tachometer Unit. . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . .. . . . . . .345
3.13. DIAGNOSTIC ON/OFF SWITCH. . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . .347
Testing Diagnostic On/Off Switch And Circuit.. .. .. .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. .. .. . .. .. ..347
3.14. CRUISE CONTROL. .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. .349
Testing Cruise Control On/Off Switch and Circuits. .. .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . ..349
Testing Cruise Set/Resume Switch and Circuits. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. .350
3.15. VEHICLE SPEED SENSOR.. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . ..352
Inspecting And Adjusting the Vehicle Speed Sensor (VSS). .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..352
Testing Vehicle Speed Sensor. . .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . ..352
Testing Vehicle Speed Sensor Circuits To ECM. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. .354

4. COMPONENT LOCATIONS. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . ..355

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1. DESCRIPTION
This chapter covers International installed components and circuits that directly interact with the Cummins ISM
and AHD (AHD is synonymous with Signature Series) engines. This chapter provides:

• Operation descriptions of International installed components and circuits which work with the Cummins
engine controls.
• Troubleshooting charts for those circuits and components installed by International.
• Locations for International installed circuits.

Refer to the Cummins Engine Manual furnished with the vehicle for other information.

The Cummins ISM and AHD engines use the CM570 engine controller. The controller provides many
engine/vehicle functions including:

• Cruise/PTO Controls
• Tachometer/Speedometer Input To Gauges
• Idle Shutdown
• Adjustable Low Idle Speed (In-Cab)
• Engine Cooling Fan Control
• Self Diagnostics
• Engine Protection System
• Engine Brake Control
• J1939 Datalink (Used for Diagnostics and to Interface With Transmission and ABS).

Refer to the Cummins Engine Manual furnished with the vehicle for additional feature information.

Since each engine control system is electronically programmable to individual owner specifications, the
operating parameters will vary from vehicle to vehicle. These parameters include: maximum cruise speed,
shift schedules, governor type (automotive type or variable speed), idle RPM, full engine shutdown as part
of the engine protection system and many others.

The electronic control module (ECM) is the control center of the system. The ECM receives input from
Cummins and International sensors and switches, processes the information, then uses electrical signals
to control engine and vehicle functions.

The ECM receives inputs from International installed components including:

• Vehicle Speed Sensor (VSS)

• Throttle Position Sensor (TPS)
• Idle Validation Switch (IVS)
• Service Brake Switch
• Clutch Switch
• Low Coolant Level Switch
• ABS/Traction Control Controller

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• Engine Fan Operation

The ECM receives information from the sensors and switches and sends signals to the injectors, fuel shut off
valve and engine brake relay.

2. OPERATION
Refer to the Cummins AHD and ISM — ENGINE CONTROLS circuit diagrams in CTS-5298 or S08225.

The ECM is connected to the International electrical system at two points

A. International engine harness 50–way ECM connector (1091) connects to ECM port C-1. This
connector links several International sensors, switched power, unswitched power ground,
switches, diagnostic connector to the ECM and the J1939 data link. The J1939 data link will
interface with the transmission and ABS as required.
B. International 31–way connector (1093) connects to the Cummins sensor harness. This connector
links the vehicle speed sensor, low coolant switch, air conditioner power switch and engine fan
controls to the ECM.

2.1. ECM POWER

Power is supplied at all times to the ECM directly from the battery. Circuits 14A and 14B run from the
positive battery post to 15 amp fuses. Circuits 14C and 14D run from the fuses to connector (675), then to
ECM power connector (1094). Circuits 14C and 14D are split into circuits 14CJ, 14CK, 14CH, 14CG, and
14CF to 50–way ECM connector (1091).

The ECM is grounded from the battery on circuit 11G which is split into circuits 11GCF, 11GCB, 11GCK,
11GCJ, and 11GCH for input to 50–way ECM connector (1091).

Turning the key switch to the ignition or start position applies power to circuit 13Z, 5A fuse F6–D and circuit
13D to the 50–way ECM connector (1091).

2.2. ATA DATA LINK CONNECTOR

The six pin ATA data link connector (137) allows an electronic service tool (EST) to communicate with the
ECM. The data link carries serial data transmissions between the ECM and the electronic service tool and
between the ECM and the speedo/tachometer cluster. Thus, the ECM provides vehicle and engine information
to the speedo/tachometer and the EST.

The ATA data link connector (137), which is located on the left instrument panel, has circuits in four of the
six cavities. The data link circuits are a twisted wire pair because twisting the wires helps shield them from
interference. The circuits are as follows:

Circuit 98A(+) is the positive data link connection and it is fed by the positive data link connector (514), the
jumper bus bar, circuit 98(+), connector (190), and circuit 98(+) coming from the ECM connector (1091).

Circuit 98C(-) is the negative data link connection and it is fed by the negative data link connector (515), the
jumper bus bar, circuit 98B(-), connector (190) and circuit 98B(-) coming from the ECM connector (1091).

Circuit 97DL is a 12 volt feed and is fed from the battery adapter (498), circuit 14BK and 20A fuse F5–D.
Thus it provides power for the electronic service tool.

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 9 CUMMINS ISM AND AHD ENGINE SYSTEM 323

Circuit 11–GR, 11–GT is connected to the panel lights ground adapter (506) and provides a ground for the
electronic service tool.

2.3. DIAGNOSTIC ON/OFF SWITCH

A lighted diagnostic on/off switch is provided for on-board diagnostics. The switch is connected to the ECM
common/ground connection by way of ECM connector (1091), circuits 97–GA, connector (190), and circuits
97–GA and 97–GE. Moving the switch to the on position, closing the switch, applies the ground to circuit
97AM, connector (190) and circuit 97AM to the Cummins engine connector (1091). This tells the ECM that the
diagnostic on/off switch has been turned on. Thus, the ECM will switch modes to display fault codes or the
absence of codes by flashing the engine warning light and the stop engine light.

2.4. IDLE/DIAGNOSTIC SWITCH

The lighted two-position momentary idle/diagnostic switch is a dual function switch. The switch adjusts the
low engine idle speed and is also used during on-board diagnostics (when the diagnostic switch is in the on
position) to move through the diagnostic fault code list.

The engine idle speed can be adjusted by the switch in increments of 25 RPM by toggling the switch.
Maximum idle speed is 800 RPM and minimum idle speed is 550 RPM. When the idle has been changed and
the key turned off, the new setting is saved in memory. This feature is owner selected and can be turned off
with an electronic service tool.

The switch is connected to the ECM common/ground connection by way of ECM connector (252), circuit
97–G and 97–GA, connector (190) and circuits 97–GA and 97–GD. Momentarily placing the switch in the
increment position applies ground to circuit 97AV, connector (190) and circuit 97AV to the ECM (252). This
causes the engine idle RPM to increase 25 RPM.

Momentarily placing the switch in the decrement position applies ground to circuit 97AU, connector (190) and
circuit 97AU to the ECM (252). This causes the engine idle RPM to decrease 25 RPM.

2.5. ELECTRONIC ACCELERATOR PEDAL ASSEMBLY

The CM570 ECM utilizes an electronic accelerator pedal assembly that includes an integrated throttle position
sensor (TPS) and idle validation switch (IVS). The accelerator pedal assembly is serviceable, to the extent that
the IVS switch is replaceable without replacing the whole assembly.

The TPS is attached to the accelerator pedal and acts like a potentiometer. Movement of the pedal results in
a variable signal being sent to the ECM that is proportional to pedal position. A 5 volt signal from the ECM
connector (1091) is applied to circuit 99A, connector (190), circuit 99A and the TPS/IVS (267). The variable
wiper signal (varies with pedal position) from TPS/IVS (267) is returned to the ECM over circuit 99, connector
(190), circuit 99 and ECM connector (1091). This variable signal tells the ECM the position of the accelerator
pedal. The TPS (267) is grounded through circuit 99–G, connector (190) and circuit 99–G to the ECM (1091).

NOTE – Any time the accelerator pedal sensor (TPS) is disconnected from the ECM with the key switch
on, the TPS and ECM must be recalibrated.

The IVS is used to indicate when accelerator pedal is in the low idle position and when the pedal is not in
the low idle position. A ground path from the ECM connector (1091), circuit 97–GA, connector (190), circuit
99–GA is applied to the TPS/IVS (267).

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When the accelerator is in the low idle position, the IVS (267) applies a ground signal to circuit 99B, connector
(190) and circuit 99B to the ECM (1091). When the accelerator is not in the idle position, the IVS (267) applies
a ground signal to circuit 99C, connector (190) and circuit 99C to the ECM (1091).

The ECM analyzes the signals received from the TPS and IVS to make certain that the signals fall within
certain parameters. For example: if the IVS signal indicates that the accelerator pedal is in the idle position,
the ECM expects to see a TPS signal that indicates that no throttle is applied. If it does not see a logical
response from both, a fault code may be logged.

The ECM and accelerator pedal must be calibrated to one another for proper engine response. Therefore,
the ECM and accelerator pedal must be calibrated when the accelerator pedal is initially installed, when an
accelerator pedal is replaced, when a new calibration is downloaded to the ECM, or when the accelerator
pedal wiring is disconnected at the pedal, the cab floor, or the ECM connector. To recalibrate the ECM and the
accelerator pedal, move the key switch to ignition position, slowly move the accelerator pedal from idle position
to fully depressed position and then release. Repeat this cycle two more times to assure proper calibration.

2.6. COOLANT LEVEL SWITCH

The coolant level switch is a fluid level actuated switch that sends two signals to the ECM, thus providing a
warning when coolant is being lost. It is mounted in the coolant surge tank. The coolant level switch is an
electronic switch that operates on the electrostatic or capacitance principle and cannot be tested with a
multimeter. The probe extends into the coolant and produces a change in capacitance when coolant displaces
air immediately surrounding the probe. This change is converted in the switch to an on/off solid state switch
closure indicating the absence or presence of coolant. The switch is electrically insulated providing a slick,
non-fouling surface as well as good electrical characteristics to prevent current flow into the coolant. The low
coolant level switch connects to the engine harness at connector (249). Four circuits from connector (249)
connect the low coolant switch to the ECM through the 31–way ECM connector (1093).

The coolant level switch (249) receives a 5 volt signal on circuit 34B(5V) from the ECM (1093). When the
coolant level is above the probe, the switch sends a high signal (3.5 volts minimum) on circuit 34A and a low
signal (0.5 volt maximum) on circuit 34 to the ECM (1093).

When the coolant level is below the probe, the switch sends a low signal (0.5 volt maximum) on circuit 34A and
a high signal (3.5 volts minimum) on circuit 34 to ECM (251).

The low coolant level switch is grounded through circuit 34–G to ECM (1093).

NOTE – The low coolant level switch cannot be tested with a multimeter in the ohmmeter mode. This is
because the switch is an electronic switch and not a mechanical switch.

2.7. CRUISE CONTROL

The cruise control system has three modes of operation: off, standby and active. The off position of the on/off
switch turns cruise control off. The standby mode occurs when the driver switches the cruise control on/off
switch to the on position. The driver can then achieve the active mode by toggling the set/resume switch
after reaching the desired road speed.

Once the system is active, the driver can accelerate beyond the set speed by depressing the accelerator
pedal. When the pedal is released, cruise control is reactivated when the vehicle speed reaches the previously
set speed.

Cruise is deactivated, and returns to the standby mode in several ways: the brake or clutch pedal is depressed,
or the vehicle speed (mph) drops below 30 mph.

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 9 CUMMINS ISM AND AHD ENGINE SYSTEM 325

The resume switch can be used to reactivate cruise at the previous set speed, or the set switch can be used
to establish a new set speed.

While in the active mode, the coast feature is used to decrease vehicle speed and establish a new lower set
speed. By holding select switch in the coast position vehicle speed decreases until the switch is released;
the speed at release becomes the new set speed.

While in the active mode, the accelerate feature is used to increase the vehicle speed and establish a new
higher speed. By holding the select switch in the accel. position, vehicle speed increases until the switch is
released; the speed at release becomes the new set speed.

The cruise control switches are used as PTO or idle adjustment controls when the vehicle road speed is not
present (this is a customer selected parameter). The cruise set/resume switch is also used during on-board
diagnostics (when the diagnostic switch is in the on position) to move through the diagnostic fault code list.
Refer to the operators manual furnished with the vehicle for specific cruise control operating instructions.

When the vehicle is not moving and the cruise on/off switch is off, the engine idle speed can be adjusted by
the set/resume switch in increments of 25 RPM by toggling the switch. Maximum idle speed is 800 RPM
and minimum idle speed is 550 RPM.

When the vehicle is not moving and the cruise on/off switch is on, the PTO speed can be adjusted with
the set/resume switch.

The lighted cruise control on/off switch (435) receives a ground signal on circuits 97–GC, 97–GA, connector
(190), on circuit 97–GA from (1091). In the on position, a ground signal is sent from the switch on circuit
97AE, connector (190) and circuit 97AE to ECM connector (1091) terminal 23. This indicates to the ECM
that the cruise control switch is in the on position. In the off position, circuit 97AE returns to its 12 volt value,
indicating to the ECM that the switch is off.

The lighted cruise set/resume switch is a momentary switch. This switch receives a ground signal on circuits
97–GB, connector (190) on circuit 97–GA, from (1091). The cruise selector switch sends a ground signal from
the switch on circuit 97AB, connector (190) and circuit 97AB to the ECM connector (1091) terminal 14 while in
the set/accel. position. In the resume/coast position, the switch sends a ground signal by way of circuit 97AA,
connector (190) and circuit 97AA to the ECM connector (1091) terminal 24.

2.8. BRAKE SWITCH

The brake switch (141) receives a ground signal on circuit 97–GB, through connector (190) on circuit 97–GA
from (1091). While the brake pedal is released, the switch is closed supplying a ground on circuit 97AL
through connector (190) to ECM connector (1091).

When the brake is applied the ground will be removed signaling the ECM that the brake has been applied.

2.9. CLUTCH SWITCH

The clutch switch (294) is a N.O. momentary switch, and its contacts are held closed when the clutch pedal
is released.

The switch is provided a ground path over circuits 97–GH, 97–GH, through connector (190) on circuit 97–GA
from (1091). The clutch switch (294) sends a ground signal by way of circuit 97AH, connector (190) and circuit
97AH to the ECM connector (1091) terminal 4 while the clutch pedal is released.

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2.10. VEHICLE SPEED SENSOR

The vehicle speed sensor (1099) feeds a VSS signal to the ECM (1091) by way of circuits 97A and 97AK
through connector (190).

Two types of sensors are available. The threaded (adjustable) sensor ids used in most transmissions. A new
push-in (non-adjustable) sensor is used on some transmissions.

2.11. ENGINE BRAKE SWITCHES

The lighted engine brake on/off switch (434) receives a ground signal on circuits 24–G, through connector
(190) on circuit 97–GA from (1091). In the on position, a ground signal is sent from the switch on circuit 24AD
to engine brake selector switch (433).

When lighted switch (433) is placed in the first position, a ground is applied to circuit 24AE, connector (190),
and circuit 24AE to the ECM (1091). This tells the ECM to enable the brake solenoid for the front three cylinders
on the ISM engine and enables the solenoids for two cylinders on the AHD engine when braking is called for.

When switch (433) is placed in the second position, a ground is applied to circuit 24AF (and 14AP with the
AHD), through connector (190) to ECM (1091). This tells the ECM to enable the brake solenoid for the
rear three cylinders on the ISM engine and enables the solenoids for four cylinders on the AHD engine
when braking is called for.

When switch (433) is placed in the third position, a ground is placed on circuit 24E. Ground is also placed on
circuit 24AF (and 24AP with the AHD), through connector (190) to the ECM (1091). This tells the ECM to
enable the brake solenoids for all cylinders on the ISM engine and the AHD engine when braking is called for.

2.12. GAUGES AND WARNING LIGHTS

Refer to separate gauge and warning lights sections in GROUP 08 — ELECTRICAL in the CTS-5000 Master
Service Manual for information on speedometer, tachometer, gauges, and warning lights.

2.13. J1939 DATA LINK

The CM570 ECM uses a J1939 data link to communicate with the antilock brake system and some types
of transmission.

A. Circuit 98YL(+) is the positive data link connection. It originates from ECM connector (1091),
terminal 46. The circuit is connected to J1939 terminating resistor connector (1098), terminal
A, J1939 backbone connector (1097), terminal A, and J1939 cap diagnostic connector (1095),
terminal A.
B. Circuit 98GN(-) is the negative data link connection. It originates from ECM connector (1091),
terminal 37. The circuit is connected to J1939 terminating resistor connector (1098), terminal C,
J1939 backbone connector (1097), terminal C, and J1939 cap diagnostic connector (1095),
terminal B.
C. Circuit 98SHD is the data link shield connection. It originates from ECM connector (1091), terminal
36. The circuit is connected to J1939 terminating resistor connector (1098), terminal B, J1939
backbone connector (1097), terminal B, and J1939 cap diagnostic connector (1095), terminal C.

3. TROUBLESHOOTING
Refer to the Cummins AHD and ISM — ENGINE CONTROLS circuit diagrams in CTS-5298 or S08225.

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 9 CUMMINS ISM AND AHD ENGINE SYSTEM 327

This section includes troubleshooting charts for International installed circuits and components that are part of
the CM570 Electronic Control system. To begin the troubleshooting process, refer to the appropriate Cummins
manual and follow their directions. If the Cummins diagnostics (fault codes) indicate that the suspect circuits
are International circuits or components, then use the charts in this section.

Refer to the CTS-5298 or S08225 Circuit Diagram Book.

The EZ-Tech or PRO-LINK 9000 EST can also be used to determine if the International switches and
components are working properly. If they are not, use a Fluke digital multimeter (DMM) to troubleshoot
the circuits.

If the Cummins diagnostic (fault codes) or the EZ-Tech or the PRO-LINK indicate a problem with International
installed circuits, the diagnostic tables in this chapter provide step-by-step test procedures.

A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 —
ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit, by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the position are generally not covered
in detail. It is assumed that the technician knows to check for a malfunctioning switch, relay, or
solenoid.

3.1. ONBOARD DIAGNOSTICS WITH ENGINE RUNNING

All CM570 vehicles have a yellow Engine Warning light and a red Engine Stop light located in the instrument
cluster. Every time the key is turned to the ignition position, the lights come on for several seconds as a
system self-test and then turn off.

If the warning lights remain on, it is an indication that the ECM has detected a problem. The CM570 system
can show and record certain problems. The problems are shown as fault codes. The fault codes are recorded
in the ECM.

If a fault is detected (becomes active) during vehicle operation, the driver is alerted by the illumination of
either the yellow Engine Warning Light or the red Stop Engine Light. The yellow Service/Check Engine
Light may also be illuminated.

The yellow Engine Warning light turns on to warn the driver of an active component or system fault that should
be serviced as soon as possible to solve the problem, but the situation is not considered an emergency.

The red Stop Engine light turns on to warn the driver that there is a major system problem and the vehicle
should be stopped and engine shut down as soon as is safely possible.

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328 9 CUMMINS ISM AND AHD ENGINE SYSTEM

The yellow Service/Check Engine Light (engine protection system) turns on to warn the driver that:

A. Coolant temperature is out of range.

B. Oil temperature is out of range.
C. Oil pressure is out of range.
D. Intake manifold temperature is out of range.
E. Engine coolant level is below the acceptable level.

3.2. PERFORMING A DIAGNOSTIC CHECK WITH THE ENGINE OFF

A diagnostic check may be performed using the Diagnostic On/Off switch and Cruise Set/Resume. Any
error codes will be flashed through the red Engine Stop Light and yellow Engine Warning Light. If no errors
are found, both lights will stay on while the diagnostics switch is on. Consult the Cummins Operation and
Maintenance Manual furnished with the vehicle for exact procedures and fault code information.

To determine the fault codes use the following procedure:

1. Begin the procedure with the engine off.

2. Place the switch key in the off position.

3. Turn the diagnostic On/Off switch to the on position.

4. Turn the key switch to run position (not crank).

NOTE – Cummins CM570 engine diagnostics must be run with the engine NOT RUNNING.

If BOTH Yellow Engine Warning andRed Engine Stop lights come ON and stay ON, it is an indication that
no engine faults are present.

If BOTH the yellow Engine Warning and red Engine Stop lights come on momentarily and then go out, it is an
indication that engine faults are present.

If BOTH the yellow Engine Warning and red Engine Stop lights come on and stay on, it is an indication that
no engine faults are present.

5. Yellow Engine Warning light will flash once.

6. There will be a one to two second pause.

7. Red Engine Stop will flash code with one or two seconds between digits.

8. Yellow Engine Warning light will flash indicating the end of that fault code, and then start over and
repeat the same fault code.

9. To go to the second fault code, move the Set/Resume switch to the Inc. position and then release it. The
process will then repeat itself as indicated in steps 5 through 8.

10. To move back to the last or previous fault code, move the Set/Resume switch to the Dec position and then
release it. The process will then repeat itself as indicated in steps 5 through 8.

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11. To stop the diagnostics procedure, correct the faults or move the diagnostic On/Off switch to the off,
and turn the vehicle key switch to the off position.

3.3. CUMMINS ELECTRONIC SERVICE TOOL

CM570 vehicles have a data link connected to the ATA date link connector (137). The Cummins electronic
service tool can be connected to program owner-specified information into the engine, monitor the system, and
aid in troubleshooting the engine. Consult the Cummins ISM or AHD Troubleshooting and Repair Manuals.
The Cummins electronic service tool may be available at the nearest Cummins Authorized Service Center.

3.4. EZ-TECH OR PRO-LINK ELECTRONIC SERVICE TOOL (EST)

The EZ-Tech or Pro-Link 9000 EST with the appropriate software program can also be used with the Navistar
data link to read active and inactive fault codes through the data link. The use of the EST or specific codes are
not discussed in this manual as the information is part of the EZ-Tech or Pro-Link 9000 documentation.

The EZ-Tech or Pro-Link 9000 can also be used to monitor operation of various switches and controls and
perform other diagnostic tasks. The specific capabilities and operating instructions are included in the EZ-Tech
or Pro-Link 9000 documentation.

3.5. RELAYS
International circuits use suppressed relays for controlling power to load devices. The suppression feature (a
resistor circuit parallel to the relay coil) prevents voltage spikes from damaging electronic components in the
vehicle. These relays must be replaced with the correct International part.

Relays used in exposed areas such as the engine compartment are sealed relays and are a different part
number than those in the cab. The part number is embossed on the relay. There is also a circuit diagram of the
relay located on the relay body. The terminals are numbered on the relay in the same manner as in the circuit
diagrams. To test the relay, refer toTesting Relay below.

3.6. TESTING RELAY

Table 96 Testing Relay
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With relay removed, Relay, 30 >100K Go to next Replace the relay.
measure resistance to 87. ohms. step.
between terminals 30
and 87.
2. Off Measure resistance Relay, 30 <2 ohms. Go to next Replace the relay.
between terminals 30 to 87A. step.
and 87A.

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Table 96 Testing Relay (cont.)

3. Off Connect 12V lead to Go to next Replace the relay.
terminal 85 and ground step.
lead to terminal 86.
Does relay energize with
audible click?
4. Off With relay energized Energized <2 ohms. Relay Replace the relay.
(step 3), measure Relay, 30 tests
resistance between to 87. good.
terminals 30 and 87.

3.7. ACCELERATOR PEDAL TPS/IVS

The following four tests check the accelerator position sensor (TPS), the idle validation switch (IVS) and the
related International cab and engine harness circuits connected to the ECM.

NOTE – The following four tests must be performed in sequence.

The tests should be performed if a Cummins fault code indicates a problem in the circuits or if the Compulink,
EZ-Tech or Pro-Link 9000 EST indicates that the TPS/IVS is not working properly while monitoring switches. If
CompulinkTM detects a fault with the IVS circuits while monitoring switches, the display would show Idle
Validation Switch = Fault. If a fault is present while monitoring Percent Of Throttle, the percent displayed
does not indicate actual throttle position.

NOTE – The following two tests, Testing Throttle Position Sensor (TPS) and Testing Idle Validation Switch
(IVS), check operation of the TPS and IVS, but do not check the timing between the two functions.

Testing Throttle Position Sensor (TPS)

This test checks the TPS circuits in the accelerator pedal assembly. This test will help identify if the resistances
are within specifications and if there are any opens or shorts in the TPS, but will not verify the correct
switching of the IVS and TPS.

Table 97 Testing Throttle Position Sensor (TPS)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect accelerator TPS, A to 2000 to Go to Replace the TPS/IVS
pedal from cab harness at C. 3000 ohms. next switch, then recalibrate
connector (267). At pedal step. (refer to Accelerator/
side of (267) measure ECM Calibration).
resistance between
terminals A and C with
the pedal in the idle
position, then with the
pedal fully depressed.
2. Off With the pedal in the TPS B to 1500 to Go to Replace the TPS/IVS
idle position, at pedal, C. 3000 ohms. next switch, then recalibrate
measure resistance step. (refer to Accelerator/
between terminals B and ECM Calibration).
C.

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Table 97 Testing Throttle Position Sensor (TPS) (cont.)

3. Off With the pedal in the full TPS, B to 250 to 1500 Go to Replace the TPS/IVS
throttle position, at pedal, C. ohms, and next switch, then recalibrate
measure resistance idle position step. (refer to Accelerator/
between terminals B and reading ECM Calibration).
C. Is reading 1000 ohms -1000
less than reading at idle ohms.
position and between 250
and 1500 ohms?
4. Off At the accelerator pedal, TPS, A, >100K Go to Replace the TPS/IVS
measure resistance B, C, D, ohms. next switch, then recalibrate
between gnd. (metal part and E to step. (refer to Accelerator/
of pedal) and terminals A, gnd. ECM Calibration).
B, C, D, and E.
5. Off The TPS sensor checks
good. Proceed to Testing
Idle Validation Switch
(IVS) which checks the
idle validation portion of
the accelerator pedal.

Testing Idle Validation Switch (IVS)

Perform Testing Throttle Position Sensor (TPS) before performing this test.

Table 98 Testing Idle Validation Switch (IVS)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect accelerator TPS/ IVS, F >100K Go to Replace the TPS/IVS
pedal from cab harness at to E. ohms. next switch, then
connector (267). At pedal step. recalibrate (refer
side of (267) measure to Accelerator/ ECM
resistance between Calibrations).
terminals F and E with
pedal in idle position. Is it
<125 ohms?
2. Off Pedal measure resistance TPS/ IVS, F >100K Go to Replace the TPS/IVS
between terminals F to E. ohms. next switch, then
and E while slowly step. recalibrate (refer
depressing the pedal to Accelerator/ ECM
(idle to full throttle). After Calibrations).
approximately 10 degrees
of travel, is the resistance
100K ohms or more?
3. Off At pedal measure TPS/ IVS, F >100K Go to Replace the TPS/IVS
resistance between to D. ohms. next switch, then
terminals F and D while step. recalibrate (refer
the pedal is at idle position. to Accelerator/ ECM
Calibrations).

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Table 98 Testing Idle Validation Switch (IVS) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off At pedal measure TPS/ IVS F <125 Go to Replace the TPS/IVS
resistance between to D. ohms. next switch, then
terminals F and D while step. recalibrate (refer
slowly depressing the to Accelerator/ ECM
pedal (idle to full throttle). Calibrations).
After approximately 10
degrees of travel the
resistance should be less
than 125 ohms.
5. Off At pedal measure TPS/ IVS, >100K Go to Replace the TPS/IVS
resistance between metal metal to D, E, ohms. next switch, then
part of accelerator pedal and F. step. recalibrate (refer
and terminals D, E and F. to Accelerator/ ECM
Calibrations).
6. Off The TPS/IVS pedal
assembly checks good.
Note that this test is not
able to check the timing
between TPS and IVS
functions.

Testing Accelerator Pedal (TPS/IVS) System for “Short or Open” Circuits

This test checks the cab and engine harness TPS/IVS circuits for opens, shorts to ground, shorts to “hot”
circuits and shorts to other circuits in the harness.

Perform the preceding test before performing this test.

Table 99 Testing Accelerator Pedal (TPS/IVS) System for “Short or Open” Circuits
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With (267) disconnected, Go to next Replace connector
disconnect connector step. terminals if damaged.
(1091) from ECM and If ECM pins are
inspect ECM connector. damaged, have
Connector and ECM pins Cummins dealer
OK? replace ECM. Refer
to Accelerator/
ECM Calibration to
recalibrate the ECM to
TPS/IVS.

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Table 99 Testing Accelerator Pedal (TPS/IVS) System for “Short or Open” Circuits (cont.)
2. Off At connector (1091) use (1091), >100K Go to next Locate short to ground
test leads and measure 99B, 99C, ohms. step. in circuit where terminal
resistance to gnd. at 97-GA, resistance is less than
terminals 3, 13, 49, 47, 99, 99A 100K ohms, then repair.
48 and 10 (circuits 99B, and 99G
99C, 97-GA, 99, 99A and to gnd.
99-G). Do not use probes
or leads other than
Cummins P/N 3822758
or the connector could be
damaged.
3. Off At connector (1091) use (1091), >100K Go to next Locate short between
test leads and measure between ohms. step. any circuits where
resistance between 99B, 99C, resistance between
terminals 3, 13, 49, 47, 97-GA, terminals is less than
48 and 10 (circuits 99B, 99, 99A, 100K ohms, then repair.
99C, 97-GA, 99, 99A and 99-G
and 99-G) and all other and all
terminals in (1091). other
circuits.
4. On At connector (1091) (252), <1.5 Go to Locate short to
use test leads and 99B, 99C, volts. Testing unwanted voltage
measure voltage to gnd. 97-GA, TPS/IVS source in any circuit
at terminals 3, 13, 49, 47, 99, 99A Circuits for where more than
48 and 10 (circuits 98B, and 99-G Continuity. 1.5 volts is present,
99C, 97-GA, 99, 99A and to gnd. then repair. Go
99-G). to Accelerator/
ECM Calibration
to recalibrate ECM/
accelerator pedal.

Testing TPS/IVS Circuits for Continuity

This test checks the individual TPS and IVS circuits (cab and engine harness) for correct resistance while
disconnected from the accelerator pedal assembly and ECM. Perform the preceding three tests before
performing this test.

Table 100 Testing TPS/IVS Circuits for Continuity

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off At ECM connector (1091) (267), 99 <5 ohms. Go to next Locate cause of out-of-
use test lead to jumper to 99A step. specification resistance
terminal 47 to 48 (circuit in either circuit 99 or
99 to 99A). At connector 99A(5V), then repair.
(267) measure resistance Refer to Accelerator/
between terminals B and ECM Calibration to
C (cir. 99 to 99A). Do recalibrate ECM/
not use probes or leads accelerator pedal.
other than Cummins

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Table 100 Testing TPS/IVS Circuits for Continuity (cont.)

P/N 3822758 or the
ECM connector could be
damaged.
2. Off At connector (1092) (267), < 5 ohms. Go to next Locate cause of
use test lead to jumper 99-G to step. out-of- specification
terminal 497to 49 (cir. 99 99. resistance in circuit
to 99-G). At connector 99-G, then repair.
(267) measure resistance Refer to Accelerator/
between terminals A and ECM Calibration to
B (cir. 99-G to 99). recalibrate ECM/
accelerator pedal.
3. Off At connector (1091) (267), 99 < 5 ohms. Go to next Locate cause of
use test lead to jumper to 99C. step. out-of- specification
terminal 47 to 3 (cir. 99 resistance in circuit
to 99C). At connector 99C, then repair.
(267) measure resistance Refer to Accelerator/
between terminals B and ECM Calibration to
D (cir. 99 to 99C). recalibrate ECM/
accelerator pedal.
4. Off At connector (1091) (267), 99 < 5 ohms. Go to next Locate cause of
use test lead to jumper to 99B. step. out-of-specification
terminal 47 to 13 (cir. resistance in circuit
99 to 99B). At connector 99B, then repair.
(267) measure resistance Refer to Accelerator/
between terminals B and ECM Recalibration
E (cir. 99 to 99B). to recalibrate ECM/
accelerator pedal.
5. Off At connector (1091) (267), 99 < 5 ohms. Go to next Locate cause of
use test lead to jumper to 99-GA. step. out-of-specification
terminal 47 to 10 (cir. 99 resistance in circuit
to 97-G). At connector 99B, then repair.
(267) measure resistance Refer to Accelerator/
between terminals B and ECM Calibration to
F (cir. 99 to 99-GA). recalibrate ECM/
accelerator pedal.
6. Off If the preceding four tests
have been performed
and defects were not
noted, the TPS and IVS
circuits check good.
If the problem is still
present, replace the
accelerator pedal. If
this does not correct the
problem, have Cummins
dealer diagnose the ECM
operation.

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 9 CUMMINS ISM AND AHD ENGINE SYSTEM 335

Accelerator/ECM Calibration

The electronic accelerator pedal assembly and the ECM must be calibrated when:

A. The pedal assembly is initially installed.

B. The pedal assembly or sensor is replaced.
C. The accelerator pedal is disconnected (at any point in the circuitry) and the key switch is placed in
the ON position.

To recalibrate the accelerator pedal and ECM:

A. The vehicle key must be in the on position.

B. Depress the accelerator pedal slowly through the complete range of movement, then release.
Slowly depress and release, three times in this manner. This completes the calibration process.

3.8. LOW COOLANT SWITCH

First check for proper coolant levels. If coolant levels are not low, this test would be performed if Cummins
diagnostic codes were logged indicating a low coolant condition or other circuit fault.

This test procedure requires a VOM to check the International harness for opens, shorts to ground, or shorts
to other circuits in the International harness. The low coolant sensor has complex circuits and a VOM
should not be used to test the sensor as it may damage the circuits.

Testing Low Coolant Level Switch And Circuits

Table 101 Testing Low Coolant Level Switch And Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect 31-way (1093), >100K Go to Locate short between
connector (1093) from between ohms. next any circuits where
Cummins connector. 34B(5V), step. resistance between
Disconnect (249) from 34-G, 34A terminals is less than
low coolant switch. and 34 and 100K ohms, then
At connector (1093) all other repair.
measure resistance circuits.
between terminals 7, 19,
5 and 8 (circuits 34B[5V],
34-G, 34A and 34) and all
other terminals in (1093).
2. Off At (1093) measure (1093), >100K Go to Locate short to gnd.
resistance to gnd. at 34B(5V), ohms. next in any circuit(s) where
terminals 7, 19, 5 and 8 34-G, 34A step. resistance is less
(circuits 34B[5V], 34-G, and 34 to than 100K ohms, then
34A and 34). gnd. repair.
3. On At (1093) measure (1093), 34B <1.5 Go to Locate short to
voltage to gnd. at (5V), 34-G, volts. next unwanted voltage
terminals 7, 19, 5 and 8 34A and 34 step. source in any circuit(s)
(circuits 34B[5V], 34-G, to gnd. where voltage is more
34A and 34). than 1.5V, then repair.

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Table 101 Testing Low Coolant Level Switch And Circuits (cont.)
4. Off Measure resistance of 34, 34A, <5 ohms. Go to Locate open or poor
circuits 34, 34A, 34-G 34-G, and next connection in circuit(s),
and 34B(5V) between 34B(5V) step. if resistance is more
connectors (249) and between than 5 ohms, then
(1093). (249) and repair.
(1093).
5. Off The low coolant switch
circuits check good. If
problem is still present,
replace low coolant
switch. If problem
persists, have Cummins
dealer diagnose ECM
operation.

3.9. POWER SUPPLY CIRCUITS TO ECM

This test checks the unswitched battery power feed to the ECM and the ECM ground circuit that is part of the
Battery Feed Harness. Check the two 15A Cummins fuses before performing this test.

NOTE – Batteries must be fully charged before performing this test.

Testing Unswitched Battery Power Circuits And ECM Ground Circuit

Table 102 Testing Unswitched Battery Power Circuits And ECM Ground Circuit
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Check ECM power Good Go to Correct poor
harness connector at con- nec- next connections.
starter circuits 14A, tion. step.
1B and 11-G and at
connector (675) and
(1094) for clean, tight
connections.
2. Off Check the two 15 amp ECM fuses. <5 ohms. Go to Locate cause of
fuses located in the next overload condition,
engine harness for open step. then correct. Replace
condition. with correct rated fuse.
3. Off Disconnect ECM power (1094), 4C 12 ± 1.5 Go to Locate cause of low
connector (1094) and 14D to volts. next or no voltage in circuit
from Cummins engine gnd. step. 14C or 14D from
harness. Measure batteries, then repair.
voltage to gnd. at circuits
14C and 14D. Battery
voltage present?

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Table 102 Testing Unswitched Battery Power Circuits And ECM Ground Circuit (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off At connector (1094) (1094), 14C 12 ± 1.5 Go to Locate open or high
measure voltage between to 11-G. volts. next resistance in circuit
circuits 14C and 11-G. step. 11-G between (1094)
Battery voltage present? and batteries, then
repair.
5. On At connector (1094) (1094), >7 volts. Go to Locate cause of
measure voltage between 14C to next excess voltage drop in
circuits 14C and 11-G 11-G while step. cranking circuit, then
while cranking engine. cranking. repair.
6. Off Unswitched battery power
circuits and ECM gnd.
circuit at connector (1094)
checks good.

Testing Switched Ignition Power To ECM

Table 103 Testing Switched Ignition Power To ECM

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Check 5A fuse F6-D for F6-D <1 ohm. Go to next Locate cause of
open condition. step. overload condition,
then repair. Replace
fuse.
2. On Measure voltage to 13Z to gnd. 12 ± 1.5 Go to next Locate cause of no
ground at input circuit volts. step. or low voltage in 13Z
(13Z to F6-D fuse). from key switch.
3. Off/On Disconnect engine (1091), 38 12 ± 1.5 Go to next Locate open in circuit
harness 50-pin ECM to gnd. volts. step. 13D between fuse
connector (1091) from and connector (1091)
Cummins harness. Turn and repair.
key on, measure voltage
to gnd. at connector
(1091) terminal 38 (circuit
13D).
4. Off Measure voltage between (1091), 38 12 ± 1.5 Switched Locate open in
terminal 38 (circuit 13D to each volts. ignition circuit between
and each terminal 29, terminal voltage engine ground and
30, 50, 40 and 39) (29, 30, 50, circuit connector (1091),
(circuits 11-GCF, 11-GCB, 40 and 39). to ECM then repair.
11-GCK, 11-GCJ and checks
11-GCH). good.

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3.10. SERVICE BRAKE AND CLUTCH SWITCHES

This test would be performed if the Electronic Service Tool (EST) displayed an incorrect switch position or
Cummins diagnostic codes indicate a problem may be present.

Testing Clutch Switch

Table 104 Testing Clutch Switch

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Disconnect clutch switch Clutch <2 ohm. Go to Step 3. Check switch
connector (294) from switch adjustment. Go to
cab harness. With clutch across next step.
pedal released, measure pigtail
resistance between the terminals
pigtail terminals. (294).
2. Off With clutch pedal Replace and Adjust clutch
depressed to the bottom adjust clutch switch. Go to
of the free travel position switch. Go to Step 1.
(approx. 1.7 inches or Step 1.
43 mm from pedal stop
plate), the u-bolt plate
should touch the switch
actuator arm. When
the clutch pedal returns
to the stop, the switch
should actuate (to closed
position) with an audible
click. Is clutch switch
adjusted properly?
3. Off Depress clutch pedal Clutch >100K Go to next If switch is not
and measure resistance switch ohms. step. properly adjusted,
between clutch switch across adjust and retest.
pigtail connector (294) pigtail If switch was
terminals. terminals properly adjusted,
(294). replace the
switch.
4. Off Check clutch switch for Clutch >100K Clutch switch Replace the
short to gnd. With switch switch each ohms. checks good. clutch switch,
disconnected, measure pigtail to Perform then adjust.
resistance to gnd. at each gnd. Testing
switch terminal. Clutch Switch
Circuits
for "Open
and Short"
Condition.

Testing Clutch Switch Circuits for "Open and Short" Condition

Perform Testing Clutch Switch before performing this test.

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CAUTION – When testing at ECM connector (1091), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 105 Testing Clutch Switch Circuits for "Open And Short" Condition
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With clutch switch Go to next Replace damaged
disconnected, remove step. harness connector
ECM connector (1091) terminals if
from the ECM. ECM damaged. If ECM
harness connector or pins are damaged,
ECM pins OK? have Cummins
dealer replace
ECM. Refer to
Accelerator/ECM
Calibration to
recalibrate ECM/
accelerator pedal.
2. Off Set service brake using (1091), >100K Go to next Locate short to
trailer hand valve. 97AH and ohms. step. gnd. in circuit
Disconnect clutch switch 97-GA to where resistance
(294). Use test leads gnd. at terminal was less
and measure resistance than 100K ohms,
to ground at connector then repair.
(1091) terminal 2 and 10
cir. 97AH and 97-GA).
3. Off Use test leads and (1091), >100K Go to next Locate short
measure resistance 97AH and ohms. step. between circuits,
between terminals 2 and 97-GA and then repair.
10 (cir. 97AH and 97-GA) all other
and all other terminals in circuits.
connector (1091).
4. On At connector (1091), (1091), <1.5 The clutch Locate short to
use test leads and 97AH and volts. switch unwanted voltage
measure voltage to gnd. 97-GA to circuits source in circuit with
at terminals 2 and 10 (cir. gnd. are free more than 1.5 volts,
97AH and 97-GA). of short then repair.
circuits.
Perform
Testing
Clutch
Switch
Circuits for
Continuity.

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Testing Clutch Switch Circuits For Continuity

CAUTION – When testing at ECM connector (1091), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 106 Testing Clutch Switch Circuits For Continuity

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off At ECM connector (1091) (294) <5 Go to Locate open or poor
use test lead to jumper 97AH to ohms. next step. connection in circuit 97AH
terminal 2 (cir. 97AH) gnd. between connectors
to gnd. At clutch switch (1091) and (294), then
connector (294) measure repair.
resistance of 97AH to gnd.
2. Off At ECM connector (1091) (294), <5 Go to Locate open or poor
use test lead to jumper 97AH to ohms. next step. connection in circuit
terminal 2 to 10 (cir. 97-GH. 97-GH or 97-GA between
97AH to 97-GA). At connectors (1091) and
clutch switch connector (294), then repair.
(294) measure resistance
between circuits 97AH
and 97-GH.
3. Off The clutch switch circuits
and switch check good.

Testing Service Brake Switch (141)

Table 107 Testing Service Brake Switch (141)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector Brake <2 Go to next Replace the brake
(141) from brake switch. pressure ohms. step. switch.
With brakes released, switch
measure resistance across
across switch terminals. terminals.
Switch should be closed.

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Table 107 Testing Service Brake Switch (141) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off Apply service brakes Brake >100K Go to next Replace the brake
and measure resistance pressure ohms. step. switch.
across the brake switch
pressure switch. Switch across
should be open. NOTE: terminals.
Sufficient air pressure
must be present to
apply service brakes
for this test step.
3. Off Measure resistance to Brake >100K Reconnect Replace the brake
gnd. at both brake switch pressure ohms. (141) to switch.
terminals with service switch both brake switch.
brakes applied, and with terminals to Perform
brakes released. Both gnd. Testing
should be isolated from Service
ground at all times. Brake Switch
Circuits
for "Open
and Short"
Condition.

Testing Service Brake Switch Circuits for "Open and Short" Condition

Perform Testing Service Brake Switch (141) before performing this test.

CAUTION – When testing at ECM connector (1091), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 108 Testing Service Brake Switch Circuits for "Open and Short" Condition
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off With connector (141) Go to next Replace harness
disconnected from step. connector terminals
brake switch. Remove if damaged. If ECM
connector (1091) pins damaged, have
from the ECM. ECM Cummins dealer
connector and ECM pins replace ECM.
OK?

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Table 108 Testing Service Brake Switch Circuits for "Open and Short" Condition (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off Disconnect clutch (1091), >100K Go to next Locate short to gnd.
switch. Use test leads 97AL and ohms. step. in circuit where
and measure resistance 97-GA to resistance at terminal
to ground at connector gnd. was less than 100K
(1091) terminals 1 and ohms, then repair.
10 (circuits 97AL and
97-GA).
3. Off Use test leads and (1091), >100K Go to next Locate short between
measure resistance 97AL to ohms. step. any circuit where
between terminal 1 and 97-G A and resistance between
10 (cir. 97AL and 97-G) all other terminals is less than
and all other terminals in circuits. 100K ohms, then
connector (1091). repair.
4. On At connector (1091), (1091), <1.5 The brake Locate short to
use test leads and 97AL and volts. switch unwanted voltage
measure voltage to 97-GA to circuits are source in circuit with
gnd. at terminals 1 and gnd. free of short more than 1.5 volts,
10 (circuits 97AL and circuits. then repair.
97-GA). Perform
Testing
Service
Brake
Switch
Circuits for
Continuity.

Testing Service Brake Switch Circuits for Continuity

CAUTION – When testing at ECM connector (1091), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 109 Testing Service Brake Switch Circuits for Continuity

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off At ECM connector (1091) (141), 97AL <5 ohms. Go to Locate open or
use test lead to jumper to gnd. next poor connection in
terminal 1 (cir. 97AL) step. circuit 97AL between
to gnd. At brake switch connectors (1091) and
connector (141) measure (141), then repair.
resistance to gnd at circuit
97AL.

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Table 109 Testing Service Brake Switch Circuits for Continuity (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off At ECM connector (1091) (141), 97AL <5 ohms. Go to Locate open or poor
use test lead to jumper to 97-GF. next connection in circuit
terminal 1 to terminal 10 step. 97-GF or 97-GA
(cir. 97AL to 97-GA). At between connectors
brake switch connector (1091) and (141), then
(141) measure resistance repair.
between circuits 97AL
and 97-GF.
3. Off The service brake switch
circuits and switch
check good.

3.11. ENGINE BRAKE

In the event the engine brake fails to operate, the following chart provides a systematic series of steps to check
the switches, circuits that are installed by International.

Testing Engine Brake Components And Circuits

Table 110 Testing Engine Brake Components And Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove engine brake (434), <1 ohms. Go to next Locate open or poor
on/off switch from 24-G to step. connection in circuit
connector (434). Measure gnd. 24-G or 97-GA, then
resistance to gnd. at repair.
connector (434), circuit
24-G.
2. Off With on/off switch Go to next Replace the switch.
removed, refer to Testing step.
Engine Brake Switches
and use ohmmeter to
check switch. Switch
good?
3. Off Remove connector (433) 24AD <5 ohms. Go to next Locate open or
from selector switch. between step. poor connection in
Measure resistance of (434) and circuit 24AD between
circuit 24AD between (433). connectors (434) and
connectors (434) and (433), then repair.
(433).
4. Off Refer to Testing Engine Go to next Replace the switch.
Brake Switches and test step.
the selector switch. Switch
good?

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Table 110 Testing Engine Brake Components And Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
5. Off Re-install conn. (434) to Go to next
engine brake on/off switch step.
and place in on position.
Re-install conn. (433)
to engine brake switch
and place in position
3. Disconnect 50-way
conn. (1091) from engine
harness.
6. On At connector (1091) (1091), <1 ohms. Go to next Locate open or poor
measure resistance from 24AE, step. connection in circuit
pin 22, 31 and 32 to ground 24AF and 24AE, 24AF or 24AP
(circuit 24AE, 24AF and 24AP to between connectors
24AP to ground). gnd. (433) and (1091), then
repair.

Testing Engine Brake Switches

1. Testing Engine Brake On/Off Switch

a. With switch in on position, resistance between terminals 5 & 6 and between 2 & 3 should be less
than 5 ohms.
b. With switch in off position, resistance should be 100K ohms or more.
c. To test the LED in the switch, connect B+ test lead to terminal 7 and ground terminal 8. LEDs should
illuminate.

2. Testing Engine Brake Selector Switch With M11 Engine.

a. With switch in 3 position, resistance between terminals 2 and 3 and 6 should be less than 5 ohms.
b. With switch in 1 position, resistance between terminals 2 and 3 should be less than 5 ohms.
c. With switch in 2 position, resistance between terminals 2 and 6 should be less then 5 ohms.
d. To test the LED in the switch, connect B+ test lead to terminal 7 and ground terminal 8. LEDs should
illuminate.

3.12. ATA DATA LINK CONNECTOR (137) AND SPEEDOMETER/TACHOMETER INPUT

CIRCUITS
This series of tests provide charts for testing: (1) The Data Link circuits between the ECM and ATA Data
Link connector (137) and the speedometer/tachometer connector (421). (2) The power and ground circuits
to the ATA Data Link connector (137).

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Testing Diagnostic Connector Power and Ground Circuits

Table 111 Testing Diagnostic Connector Power and Ground Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove and check F5-D. <1 ohm. Go to next Locate cause of
20A fuse F5-D for open step. overload condition,
condition. then repair. Replace
20A fuse.
2. On Re-install fuse. At (137), 12 ± 1.5 Go to next Locate cause of no or
connector (137) measure 97DL to volts. step. low voltage in circuit
voltage at terminal C gnd. 97DL from fuse F9-C,
(circuit 97DL) to ground. then repair.
3. On At connector (137) (137), 12 ± 1.5 Go to next Locate open or
measure voltage between 97DL to volts. step. poor connection in
terminals C and E (circuits 11-GR. circuit 11-GR between
97DA and 11-GR). connector (137) and
G1 ground adapter
(453), then repair.
4. On The power and gnd.
circuits to the ATA data
link connector (137) check
good.

Testing Data Link Circuits Between Diagnostic Connector, ECM and Speedometer/Tachometer Unit

CAUTION – When testing at ECM connector (1091), do not use probes or leads other than Cummins
test lead , Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 112 Testing Data Link Circuits Between Diagnostic Connector, ECM and
Speedometer/Tachometer Unit
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect ECM conn. Harness Go to Replace harness
(1091) from the ECM. conn. OK. next conn. terminals if
Inspect conn. ECM step. damaged. If ECM
harness connector OK? pins are damaged,
have Cummins
dealer replace ECM.
Refer to Accelerator/
ECM Calibration to
recalibrate ECM/
accelerator pedal.

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Table 112 Testing Data Link Circuits Between Diagnostic Connector, ECM and
Speedometer/Tachometer Unit (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off Disconnect connector (1091), >100K Go to Locate short circuit to
(421) from speedometer/ 98B(-) and ohms. next gnd in circuit where
tachometer unit and 98(+) to step. resistance is less
if additional devices gnd. than 100K ohms, then
have been connected repair.
to (514) and (515) data
link connectors, they
must be disconnected.
At connector (1091),
using test leads, measure
resistance to gnd. at
terminals 26 and 27
(circuit 98B[+] and 98[-]).
3. On At connector (1091) (1091), >100K Go to Locate short between
use test leads and 98B(-) and ohms. next circuits where
measure resistance 98(+) and step. resistance between
between terminal 26 and all other terminals is less than
terminal 27 (circuits 98B[+] circuits in 100K ohms, then
and 98[-]) and all other conn. repair.
terminals in connector.
4. On At connector (1091) use (1091), <1.5 volts. Go to Locate short to
test leads and measure 98b(-) and next unwanted voltage
voltage to gnd. at 98(+) to step. source in circuit where
terminals 26 and 27 gnd. more than 1.5 volts
(circuits 98B[+] and 98[-]). is present at terminal,
then repair.
5. Off At connector (1091) use (137), <5 ohms. Go to Locate open or poor
test lead to jumper terminal 98C(-) to next connection in circuit
27 (cir. 98B[-]) to gnd. At gnd. step. 98B(-)/98C(-) between
connector (137) measure connectors (1091) and
resistance to gnd. at (137), then repair.
terminal B (cir. 98C[-]).
6. Off With connector (1091) (421) 47/ <5 ohms. Go to Locate open or poor
terminal 27 (circuit 98B[-]) 48(-) to next connection in circuit
still jumpered to ground, at gnd. step. 47/48(-) between
speedometer/ tachometer connectors (515) and
connector (421) measure (421), then repair.
resistance to gnd. at
circuit 47/48(-).
7. Off At connector (1091) use (137), <5 ohms. Go to Locate open or poor
test lead to jumper terminal 98A(+) to next connection in circuit
27 (cir. 98[+]) to gnd. At gnd. step. 98(+)/98(+) between
connector (137) measure connectors (1091) and
resistance terminal A (137), then repair.
(circuit 98A[+]) to gnd.

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Table 112 Testing Data Link Circuits Between Diagnostic Connector, ECM and
Speedometer/Tachometer Unit (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
8. Off With connector (1091) (421), 47/ <5 ohms. Go to Locate open or poor
terminal 27 (cir. 98[+]) still 48(+) to next connection in circuit
jumpered to ground, at gnd. step. 47/48(+) between
connector (421) measure connectors (514) and
resistance to gnd. at (421), then repair.
circuit 47/48(+).
9. Off The data link circuits
between ECM connector
(1091), diagnostic
connector (137) and
speedometer/ tachometer
connector (421) test good.

3.13. DIAGNOSTIC ON/OFF SWITCH

The diagnostic On/Off switch can be checked with CompulinkTM, EZ-Tech or Pro-Link 9000 in the switch
monitoring mode. If the switches do not operate properly, perform the following test.

Testing Diagnostic On/Off Switch And Circuit

Table 113 Testing Diagnostic On/Off Switch And Circuit

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (241) Across <5 ohms. Go to Replace the switch.
from on/off switch. With switch next
switch in on position, terminals 5 step.
measure resistance and 6.
between terminals 5 and
6.
2. Off With switch in position, Across >100K Go to Replace the switch.
measure resistance switch ohms. next
between terminals 5 and terminals 5 step.
6. and 6.
3. Off To test the LED in the Go to Replace the switch.
switch, connect B+ test next
lead to terminal 7 and step.
connect terminal 8 to gnd.
Does LED illuminate?

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Table 113 Testing Diagnostic On/Off Switch And Circuit (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off Remove ECM connector Go to Replace harness
(1091) from the ECM. next connector terminals
Inspect connector. ECM step. if damaged. If ECM
harness connector and pins are damaged,
ECM pins? have Cummins
dealer replace
ECM. Refer to
Accelerator/ECM
Calibration to
recalibrate ECM/
accelerator pedal.
5. Off Disconnect connector (1093), >100K Go to Locate short to
(1091) measure 97AM to gnd. ohms. next ground in circuit
resistance to gnd. at step. 97AM, then repair.
terminal 44 (cir. 97AM) to
ground.
6. Off At connector (1091) (1091), >100K Go to Locate short to
measure resistance from 97-GA to ohms. next ground in circuit
terminal 10 (cir. 97-GA) gnd. step. 97-GA, then repair.
to gnd.
7. Off Set service brakes using (1091), >100K Go to Locate short between
trailer hand control 97AM to ohms. next circuits where
valve, with clutch switch all other step. resistance between
disconnected, measure circuits. terminals is less than
resistance between 100K ohms, then
terminal 44 (cir. 97AM) repair.
and all other terminals in
(1091).
8. Off At connector (1091), (241), 97AM <5 ohms. Go to Locate open or poor
use test lead to jumper to gnd. next connection in circuit
terminal 44 (cir. 97AM) to step. 97AM between
gnd. At connector (241) connectors (241)
measure resistance to and (1091), then
ground at circuit 97AM. repair.
9. Off At connector (1091), use (241), 97-GE <5 ohms. Go to Locate open or
test lead and jumper to gnd. next poor connection in
terminal 10 (cir. 97-G) to step. circuit 97-GE, 97-GA
gnd. At connector (241) or 97-G between
measure resistance to connectors (241) and
gnd. at circuit 97-GE. (1091), then repair.
9. Off The diagnostic on/off
switch and circuits check
good.

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3.14. CRUISE CONTROL

When monitoring switches with a Electronic Service Tool, the cruise On/Off switch will indicate on or off.
The Set/Resume switch will indicate either Set or Res, depending on the switch position. If the switch is
not operable, the screen will be blank.

Testing Cruise Control On/Off Switch and Circuits

CAUTION – When testing at ECM connector (1091), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 114 Testing Cruise Control On/Off Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (435) Across <5 ohms. Go to Replace the switch.
from cruise On/Off switch. terminals next
With switch in on position, 5 and 6. step.
measure resistance
between terminals 5 and
6.
2. Off With switch in off position, Across > 100K Go to Replace the switch.
measure resistance terminals ohms. next
between terminals 5 and 5 and 6. step.
6.
3. Off To test the LED in the Go to Replace the switch.
switch, connect B+ test next
lead to terminal 7 and step.
connect terminal 8 to gnd.
Does LED illuminate?
4. Off Remove ECM connector Go to Replace harness
(1091) from the ECM and next connector terminals
inspect. ECM harness step. if damaged. If ECM
connector and ECM pins pins are damaged,
OK? have Cummins
dealer replace ECM.
Refer to Accelerator/
ECM Calibration to
recalibrate ECM/
accelerator pedal.
5. Off At ECM connector (1091) (1091), >100K Go to Locate short to gnd.
use test leads and 97AE and ohms. next in circuit with less
measure resistance to 97-G to step. than 100K ohms, then
gnd. at terminals 23 and gnd. repair.
10 (cir. 97AE and 97-G).

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Table 114 Testing Cruise Control On/Off Switch and Circuits (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
6. Off At connector (1091) (1091), >100K Go to Locate short between
measure resistance 23 to ohms. next circuit 97AE and
between terminal 23 and all other step. any circuit where
all other terminals in terminals. resistance between
connector. terminals is less than
100K ohms, then
repair.
7. On At connector (1091) (1091), <1.5 volts. Go to Locate short between
measure voltage from 97AE to next circuit 97AE and
terminal 23 (circuit 97AE) gnd. step. unwanted voltage
to ground. source, then repair.
8. Off At connector (1091) use (435), <5 ohms. Go to Locate open or
test lead to jumper terminal 97AE to next poor connection in
23 (cir. 97AE) to gnd. At gnd. step. circuit 97AE between
connector (435) measure connectors (1091) and
resistance to gnd. at circuit (435), then repair.
97AE.
9. Off Measure the resistance Between <5 ohms. Go to Locate open or poor
between connector (1091), (1091), next connection in circuit
terminal 10 (cir. 97-G) and terminal step. 97-GC, 97-GA or
connector (435), cir. 10 and 97-G, then repair.
97-GC. (435),
97-GC.
10. Off The cruise On/Off switch
and circuits check good.

Testing Cruise Set/Resume Switch and Circuits

CAUTION – When testing at ECM connector (1091), do not use probes or leads other than Cummins
test leads, Part No. 3822758. The connector will be damaged. The leads must fit snug without
expanding the connector terminal.

Table 115 Testing Cruise Set/Resume Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (436) Between <5 ohms. Go to Replace the switch.
from cruise set/resume switch term. next
switch. With switch in 2 and 3. step.
set position, measure
resistance between
terminals 2 and 3.

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Table 115 Testing Cruise Set/Resume Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off With switch in neutral Between >100K Go to Replace the switch.
position, measure switch term. ohms. next
resistance between 1, 2 and 3. step.
terminals 1, 2 and 3.
3. Off With switch in resume Between <5 ohms. Go to Replace the switch.
position, measure switch term. next
resistance between 1 and 2. step.
terminals 1 and 2.
4. Off To test the LED in the Go to Replace the switch.
switch, connect B+ test next
lead to terminal 7 and step.
connect terminal 8 to gnd.
Does LED illuminate?
5. Off Remove ECM connector ECM Go to Replace harness
(1091) from the ECM and harness next connector terminals
inspect. ECM harness conn. and step. if damaged. If ECM
connector and ECM pins ECM pins pins are damaged,
OK? OK. have Cummins
dealer replace
ECM. Refer to
Accelerator/ECM
Calibration to
recalibrate ECM/
accelerator pedal.
6. Off At ECM connector (1091) (1091), >100K Go to Locate short to gnd.
use test leads and 97AB to ohms. next in circuit with less
measure resistance to 97AA to step. than 100K ohms,
ground at terminals 24 gnd. then repair.
and 14 (cir. 97AB and
97AA).
7. Off At connector (1091) (1091) >100K Go to Locate short between
measure resistance between ohms. next any circuits where
between terminal 24 and 97AB and step. resistance between
14 (cir. 97AB and 97AA), 97AA, and terminals is less than
and all other terminals in all others. 100K ohms, then
the connector. repair.
8. On At connector (1091) (1091), <1.5 volts. Go to Locate short to
measure voltage to 97AB and next unwanted voltage
ground at terminals 24 97AA to step. source in circuit
and 14 (cir. 97AB and gnd. 97AA or 97AB, then
97AA). repair.

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Table 115 Testing Cruise Set/Resume Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
9. Off At connector (1091) (436), 97AB <5 ohms. Go to Locate open or
use test lead to jumper to gnd. next poor connection in
terminal 24 (cir. 97AB) to step. circuit 97AB between
gnd. At connector (436) connectors (1091)
measure resistance to and (436), then
ground at circuit 97AB. repair.
10. Off Measure the resistance Between <5 ohms. Go to Locate open or poor
between connector (1091), next connection in circuit
(1091), terminal 10 (cir. term. 10 step. 97-GC, 97-GA or
97-G) and connector and (436), 97-G, then repair.
(436), circuit 97-GB). 97-GB.
10. Off At connector (1091) (436) circuit <5 ohms. Go to Locate open or
use test lead to jumper 97AA to next poor connection in
terminal 24 (cir. 97AA) to gnd. step. circuit 97AA between
gnd. At connector (436) connectors (1091)
measure resistance to and (436), then
ground at circuit 97AA. repair.
11. Off The cruise set/resume
switch and circuits check
good.

3.15. VEHICLE SPEED SENSOR

When monitoring engine functions with an EST, if the vehicle is moving the miles-per-hour will display as
MPH=XXX (actual vehicle speed if operating properly). To test the sensor and circuits to the ECM, use the
following charts.

Inspecting And Adjusting the Vehicle Speed Sensor (VSS)

1. Disconnect engine harness connector (1099) from the sensor. Loosen the locknut and remove the sensor.
The harness connector and sensor should be free of damage or corrosion. Remove any metal shavings or
debris from the sensor.

2. To install the adjustable sensor, turn in until the sensor contacts the transmission speedometer gear,
then back out one full turn. Tighten lock nut to 15 ft-lbs. (20.3 N•m). This assures that the sensor
is adjusted properly for the next test.
Testing Vehicle Speed Sensor

Construct test leads using terminals (International Part No. 1680205C1), short length of 16 gauge wire
and alligator clips.

WARNING – A jack must never be used alone to support vehicle. The jack may lower and
serious injury could result. Always support vehicle with floor jacks. Always block wheels to prevent
vehicle from moving.

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WARNING – EXTREME CAUTION should be used to prevent personal injury resulting from
contact with rotating vehicle wheels when connecting test leads.

Table 116 Testing Vehicle Speed Sensor

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Inspect VSS for damage Go to
and proper adjustment next
before performing this step.
test. Refer to Inspecting
and Adjusting the Vehicle
Speed Sensor (VSS)
above.
2. Off Disconnect engine VSS, 600 to Go to Replace the vehicle
harness (1099) from terminal 1 800 ohms next speed sensor (VSS).
VSS and use test leads to 2. with the step.
to measure resistance adjustable
between terminal 1 and 2 sensor.
of sensor connector.
1500 to
3500
ohms
with the
push-in
sensor.
3. Off Measure resistance to VSS, term. >100K Go to Replace the vehicle
gnd. at both sensor 1 and 2 to ohms. next speed sensor (VSS).
terminals. gnd. step.
4. Off Block front wheels and Go to
place rear axles on floor next
stands. step.
5. Off Use AC voltmeter with Go to
sufficient length leads to next
avoid personal contact step.
with rotating vehicle
wheels during test.
Connect meter leads
to test leads.
6. Off Run engine at idle speed, VSS, >2.0 volts VSS Replace the VSS (refer
with transmission in high across AC checks to Inspecting And
gear. Measure voltage terminals. good. Adjusting The Vehicle
across the two sensor Speed Sensor above).
terminals. Note: Improper
sensor adjustment
will cause low, erratic
or no output.

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Testing Vehicle Speed Sensor Circuits To ECM

To check circuits between the ECM and the speedometer/tachometer unit, refer toATA Data Link Connector
(137) and Speedometer/Tachometer Input Circuits.

Table 117 Testing Vehicle Speed Sensor Circuits To ECM

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (1099) Go to Replace harness
from vehicle speed sensor. next connector terminals
Remove ECM connector step. if damaged. If ECM
(1093) from the ECM and pins are damaged,
inspect. ECM harness have Cummins
connector and ECM pins dealer replace ECM.
OK? Refer to Accelerator/
ECM Calibration to
recalibrate ECM/
accelerator pedal.
2. Off At connector (1093), use (1093), >100K Go to Locate short to gnd.
test leads and measure 97AJ and ohms. next in circuit with less
resistance to gnd. at 97AK to step. than 100K ohms, then
terminals 21 and 22 (cir. gnd. repair.
97AJ and 97AK).
3. Off At connector (1093), (1093), >100K Go to Locate short circuit
measure resistance 97AJ and ohms. next between circuits where
between terminals 21 and 97AK and step. resistance between
22 (cir. 97AJ and 97AK) all others. terminals is less than
and all other terminals in 100K ohms, then
connector. repair.
4. On At connector (1093), (1093), <1.5 Go to Locate short to
measure voltage at 97AJ and volts. next unwanted voltage
terminals 21 and 22 97AK to step. source in circuit where
(cir 97AJ and 97AK) to gnd. voltage at terminal is
ground. more than 1.5 volts,
then repair.
5. Off At connector (1093) use (1099), <5 ohms. Go to Locate open or
test leads and jumper 97AJ to next poor connection in
terminal 21 (cir. 97AJ) to gnd. step. circuit 97AJ between
gnd. At connector (1099) connectors (1093) and
measure resistance to (1099), then repair.
gnd. at circuit 97AJ.

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Table 117 Testing Vehicle Speed Sensor Circuits To ECM (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
6. Off At connector (1093) use (1099), <5 ohms. Go to Locate open or
test leads and jumper 97AK to next poor connection in
terminal 22 (cir. 97AK) to gnd. step. circuit 97AK between
gnd. At connector (1099) connectors (1093) and
measure resistance to (1099), then repair.
gnd. at circuit 97AK.
7. Off The vehicle speed sensor
circuits between the
sensor and ECM check
good.

4. COMPONENT LOCATIONS
B1 Battery Stud.. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . . . . . Power Distribution Panel
(1) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Left Side of Engine Cowl
(2) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Above Connector 3
(3) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Below Connector 2
(72) Ether Start Connector. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Front End Harness, At Lower Left of Radiator
(94) Back-up Light Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . On Transmission
(137) 6-Way Data Link Connector. . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(141) Service Brake Switch/Cruise Switch. . . . . . . . .. . . . . . Dash Panel, Left Side, Engine Side
(190) Cab Overlay to Elect. Eng. Harn.. . . . . . . . . . . .. . . . . . Right Instrument Panel
(227) Fan Solenoid . . . . . . .. . . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . At Front of Engine
(228) Refrigerant Pressure Switch . . .. . .. . .. . .. . .. . .. . . . . . On A/C Compressor
(229) Engine Oil Temp. Sender. .. . .. . .. . .. . .. . .. . .. .. . . . . . Left Side of Engine
(235) Transmission Oil Temp. (Inline). . . .. . . . . .. . . . .. . . . . . On Front of Transmission
(249) Low Coolant Level Switch. . . . . . . . . . . . . . . . . . . . .. . . . . . To Engine Harness
(267) Accelerator Pedal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . To Cab Overlay
(294) Clutch Switch Connector. . . . . . . . . . . . . . . . . . . . . .. . . . . . Near Clutch Switch
(420) Right Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Gauge Cluster
(421) Speedo./Tach. Module. .. . . .. . . .. . . .. . . .. . . .. . .. . . . . . Behind Speedo./Tach. Gauge
(422) Speedo./Tach. Module. .. . . .. . . .. . . .. . . .. . . .. . .. . . . . . Behind Speedo./Tach. Gauge
(423) Left Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Left Gauge Cluster
(424) Left Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Left Gauge Cluster
(514) Data Link — Positive. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . . . . Behind Instrument Panel/Behind Cluster
(515) Data Link — Negative. .. .. . .. .. .. .. .. . .. .. .. .. .. . . . . . Behind Instrument Panel/Behind Cluster
(1091) Electronic Control Module ECM. . . . . . . . . . . . .. . . . . . At ECM
(1093) ECM Interface Connector. . . . . . . . . . . . . . . . . . . .. . . . . . At Engine Harness near ECM
(1094) ECM Power Connector. . . . . .. . . . . .. . . . . .. . . . .. . . . . . At Engine Harness near ECM
(1099) Vehicle Speed Sensor. . . . . .. . . . . .. . . . . .. . . . . .. . . . . . On Transmission

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Figure 109 Engine Wiring, Cab

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 9 CUMMINS ISM AND AHD ENGINE SYSTEM 357

1. DASH PANEL (VIEWED FROM INSIDE ENGINE COMPARTMENT)

2. (141) BRAKE SWITCH
3. (640) STOP LIGHT SWITCH
4. (190) ELECTRONIC ENGINE CONNECTOR
5. RIGHT HAND DASH PANEL GROUND STUD
6. (3) ENGINE CONNECTOR
7. (2) CHASSIS HARNESS CONNECTOR
8. POWER DISTRIBUTION PANEL
9. SWITCHES
10. RIGHT GAUGE CLUSTER
11. SPEEDOMETER / TACHOMETER CLUSTER
12. LEFT GAUGE CLUSTER
13. (514) DATA LINK CONNECTOR
14. (515) DATA LINK CONNECTOR
15. (137) DATA LINK
16. CLUTCH SWITCH
17. FRONT END HARNESS CONNECTOR
18. THROTTLE PEDAL
19. (294) CLUTCH SWITCH CONNECTOR
20. (267) THROTTLE PEDAL CONNECTOR

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358 9 CUMMINS ISM AND AHD ENGINE SYSTEM

Figure 110 Engine Wiring, Dash Panel

1. (190) ELECTRONIC ENGINE CONNECTOR
2. RH DASH PANEL GROUND STUD
3. (2) CAB/ENGINE HARNESS CONNECTOR
4. MEGAFUSE
5. START MAGNETIC SWITCH
6. CIRCUIT 14A TO (B1) BATTERY STUD
7. CIRCUIT 17C
8. CIRCUIT 17B
9. CIRCUIT 14
10. (249) LOW COOLANT SENDER
11. TO ENGINE HARNESS

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Figure 111 Engine Wiring, Cummins ISM

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360 9 CUMMINS ISM AND AHD ENGINE SYSTEM

1. (228) A/C PRESSURE SWITCH CIRCUITS 23C AND 23–GB

2.(1091) 50–WAY OEM ECM CONNECTOR
3. (1093) 31–WAY INTERFACE CONNECTOR
4. TO ENGINE WIRING AT DASH PANEL
5. TRANSMISSION TEMPERATURE SENSOR
6. TO TRANSMISSION
7. STARTER
8. FRAME GROUND
9. ENGINE GROUND
10. (1094) ECM POWER CONNECTOR
11. CONTROL DATA LINK CONNECTOR

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Figure 112 Engine Wiring, Cummins ISM

1. (228) A/C PRESSURE SWITCH CIRCUITS 23C AND 23–GB
2. ETHER START CONNECTOR
3. ENGINE OIL TEMPERATURE CONNECTOR
4. TO ENGINE WIRING AT DASH PANEL

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Figure 113 Engine Wiring — Cummins Signature Series

1. (228) A/C PRESSURE SWITCH CIRCUITS 23C AND 23–GB
2. (1091) 50–WAY OEM ECM CONNECTOR
3. (1093) 31–WAY INTERFACE CONNECTOR
4. J1939 SERVICE CONNECTOR
5. TO ENGINE WIRING AT DASH PANEL
6. ETHER START CONNECTOR
7. OIL TEMPERATURE GAUGE CIRCUITS 30B AND 30–GB
8. (1097) SAE J1939 DATA LINK CONNECTOR USED WITH ABS/TRACTION CONTROL
9. ENGINE GROUND STUD
10. (1094) ECM POWER CONNECTOR
11. FRAME GROUND
12. J1939 TERMINATING RESISTOR

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Figure 114 Engine Wiring — Cummins Signature Series

1. (228) A/C PRESSURE SWITCH CIRCUITS 23C AND 23–GB
2. AC COMPRESSOR CLUTCH CONNECTOR
3. OIL TEMPERATURE SENDER CONNECTOR
4. TO ENGINE WIRING AT DASH PANEL
5. TO TRANSMISSION

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Figure 115 Engine Wiring, Transmission Effects

1. ENGINE HARNESS
2. (94) BACK-UP LIGHT SWITCH CONNECTOR
3. (250) VEHICLE SPEED SENSOR

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Figure 116 Engine Wiring, Starter Motor

1. CIRCUIT 17C
2. CIRCUIT 14
3. CIRCUIT 11-GS

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Figure 117 Engine Wiring, ECM — Cummins ISM

1. ECM GROUND CONNECTION
2. (1091) 50–WAY CONNECTOR
3. (1093) 31–WAY CONNECTOR

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Figure 118 Engine Wiring, ECM – Cummins Signature Series

1. ECM GROUND CONNECTION
2. (1091) 50–WAY CONNECTOR
3. (1093) 31–WAY CONNECTOR

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Figure 119 Engine Wiring, Alternator Effects — ISM

1. CIRCUIT 2-G
2. CIRCUITS 2 AND 14
3. ENGINE HARNESS

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Figure 120 Engine Wiring, Alternator Effects — Signature Series

1. CIRCUIT 2
2. CIRCUIT 14
3. CIRCUIT 2-G
4. ENGINE HARNESS

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 10 INTERNATIONAL 530E I6 HEUI ENGINES 371

Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .373

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .373
2.1. CEC POWER AND GROUND. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .374
2.2. ACCELERATOR POSITION SENSOR (APS) AND IDLE VALIDATION SWITCH (IVS).. .. .. .. .374
2.3. BAROMETRIC AIR PRESSURE (BAP) SENSOR. . . . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . .375
2.4. AIR TEMPERATURE SENSOR (ATS). .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .375
2.5. ATA DATA LINK CONNECTOR. . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . .375
2.6. DIAGNOSTIC ON/OFF SWITCH. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .376
2.7. CRUISE CONTROL/PTO SYSTEM. .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .376
2.8. CLUTCH SWITCH.. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . . .. . . . .376
2.9. COOLANT LEVEL PROBE. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . .377
2.10. VEHICLE SPEED SENSOR (VSS). .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . .377
2.11. SERVICE BRAKE SWITCH. .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .377
2.12. ANTILOCK BRAKE INTERFACE. . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .377
2.13. ENGINE BRAKE. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. .377

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .378
3.1. DETERMINING FAULT CODES.. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .378
Reading Flash Codes. . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . .379
3.2. IMPORTANT STEPS BEFORE TESTING. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .379
3.3. INSPECTING ELECTRICAL CONNECTORS. . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .380
Visual Inspection. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .380
Performing Electrical Tests at CEC Module Connector (379). . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .380
Replacing International Components. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . .380
3.4. TESTING HELLA RELAY. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .381
3.5. CEC POWER AND GROUND SYSTEM CIRCUITRY.. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .381
3.6. ACCELERATOR (APS/IVS), BAROMETRIC AIR PRESSURE (BAP) AND AMBIENT AIR
TEMPERATURE SENSOR SYSTEMS (ATS). . . . .. . . . . . . . . . .. . . . . . . . . .. . . . . . . . . . .. . . . . . . . . .. . . . . . . . . .384
3.7. DIAGNOSTIC CONNECTOR (137) AND DATA LINK CIRCUITS. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .386
Testing Diagnostic Connector Power and Ground Circuits. . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .386
3.8. TESTING DIAGNOSTIC CONNECTOR AND SPEEDOMETER/TACHOMETER POSITIVE AND
NEGATIVE DATA LINK CIRCUITS. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .387
3.9. VEHICLE SPEED SIGNAL.. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .388
Testing Vehicle Speed Sensor (303). .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .. . . .. . .389
Testing Vehicle Speed Sensor To ECM Circuits. .. . .. . . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .390
3.10. CRUISE AND PTO CONTROLS.. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .391
Testing Cruise On/Off Switch and Circuits. . .. . .. . .. . . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . . .. . .. . .391
Testing Cruise Set/Resume Switch and Circuits. . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .391
3.11. CLUTCH SWITCH (294). . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .392
Testing Clutch Switch and Circuits.. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .392
Adjusting Clutch Switch.. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. .393
3.12. SERVICE BRAKE SWITCH (141). . . . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .393
Testing Service Brake Switch and Circuits. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .393
3.13. TESTING LOW COOLANT SENSOR AND CIRCUITS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .394
3.14. ENGINE BRAKE CONTROLS. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .. . . .395
Testing Engine Brake Switches and Circuits. . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .395

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4. COMPONENT LOCATIONS. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . ..397

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1. DESCRIPTION
Refer to Diagnostic Manual EGES-175 for detailed information.

The Diamond Logic CEC is standard on International engines and provides many engine/vehicle functions
including:

A. Cruise/PTO Controls
B. Engine Diagnostics
C. Engine Protection System
D. Engine Cooling System
E. Exhaust Brake Control
F. Speedometer/Tachometer Input Signals
G. ABS/Traction Control Interface.

Refer to the International manual furnished with the vehicle for additional feature information.

Since each CEC is electronically programmable to individual owner specifications, the operating parameters
will vary from vehicle to vehicle.

The CEC receives inputs from the following International components:

A. Vehicle Speed Sensor (VSS)

B. Accel. Position Sensor (APS)
C. Idle Validation Switch (IVS)
D. Service Brake Switch
E. Park Brake Switch
F. Clutch Switch
G. Low Coolant Level Sensor
H. Cab Switches

The CEC receives inputs from sensors and switches, then outputs signals to the injectors, exhaust brake
solenoid, and other system components.

For information on remote PTO control for body builder applications, refer to Miscellaneous Information
in CT-471 Body Builder Book.

2. OPERATION
Refer to the circuit diagram I6 HEUI-ENGINE CONTROLS in CTS-5298 or S08225.

The CEC is connected to the International electrical system at CEC module connector (379).

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2.1. CEC POWER AND GROUND

The CEC receives 12 volt operating power, with the key switch in the ignition position, from the CEC power
relay. The circuitry is protected by a 40 amp fuse that is part of the battery cable assembly. The control
module ground is to the negative post of the batteries.

Power is supplied from the batteries to circuit 14A, a 40A power relay fuse, circuit 14B, positive battery
connector, circuit 14B, power connector (490), and circuit 14B to the Electronic Control Module (CEC) power
relay (396) contacts.

Power is also supplied from the (B1) battery feed stud to circuit 14BB, fuse F10B, circuit 97DCT, circuit
97CT, bulkhead connector (190), and circuit 97CT to the Module power relay coil. From the relay, power is
applied to circuit 97AH and pin 25 of the CEC (379).

When key switch (24) is moved to the ignition position, power is supplied to circuit 13AA, fuse F10C, circuit
97DS, circuit 97CR, bulkhead connector (190), and circuit 97CR to pin 24 of the CEC (379). This signals the
CEC that the ignition switch is on and causes the CEC to internally switch pin 25 to ground. This completes the
circuit for the Module power relay (396) and energizes the relay. With the relay energized, power is applied
through the relay contacts to circuit 97CM and a splice. From the splice power is applied to the CEC pins 21,
22, and 41 on circuits 97CL, 97CK, and 97AL respectively.

Grounds for the CEC pins 1, 2, 23, and 42 are through circuits 11–GW, 11–GX, 11–GY, and 11–GZ respectively,
to a splice. From the splice, ground is through circuit 11–G, the battery harness connector (490), circuit 11–G,
negative battery connector (665) and circuit 11–G to the negative battery terminal.

2.2. ACCELERATOR POSITION SENSOR (APS) AND IDLE VALIDATION SWITCH (IVS)
The Accelerator Pedal Position Sensor (APS) is a potentiometer type sensor which, when supplied with a
5 volt reference signal from the Electronic Control Module (CEC), provides a linear analog voltage signal
that indicates the driver’s demand for power. The APS signal is used in calculating desired fuel quantity
and injector timing.

The Idle Validation Switch (IVS) is a 1/12 volt switch that provides the CEC with a redundant signal to verify
when the pedal is in the idle position.

These two functions are integrated into one component mounted on the accelerator pedal. The pedal
assembly is serviceable to the extent that the APS/IVS can be replaced without replacing the complete pedal.
The engine Electronic Control Module (CEC) determines the position of the accelerator pedal by processing
the input signals from the Accelerator Position Sensor (APS) and Idle Validation Switch (IVS).

The CEC sends a regulated 5 volt signal through the black CEC module connector (379), circuit 97U, engine
connector (190), circuit 97U to a splice, and circuit 99C to the APS/IVS (267). The APS then returns a variable
voltage signal (depending on pedal position) from connector (267), circuit 99A, connector (190) and circuit
99B to CEC module connector (379). The APS is grounded through circuit 99B/97W, connector (190), and
circuit 97W/97BW to CEC (379).

The CEC learns the lowest and highest pedal positions by reading and storing the minimum and the maximum
voltage levels from the APS. In this manner the CEC “auto-calibrates” the system to allow maximum pedal
sensitivity. The CEC auto-calibrates as the key is on, but when the key is turned off, these values are lost.
When the key is turned on again, this process starts over. When the pedal is disconnected (or a new one is
installed), the pedal does not need to be calibrated, as the calibration happens when the key is turned on.

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The Idle Validation Switch (IVS) (267) receives 12 volt ignition voltage from ignition adapter (494) circuits
13BBB, fuse F10A, circuit 47A and circuit 99E. When the pedal is not in the idle position (throttle applied),
the IVS sends this 12 volt signal to the CEC over circuit 99D, clutch switch (294), connector (190), and
circuit 99D to the CEC (379).

The CEC (379) compares the inputs it receives on circuit 99B and circuit 97A from the APS/IVS to verify
when the pedal is in the idle position. If the APS signal from circuit 99B indicates throttle is being applied,
then the CEC expects to see 12 volts at IVS circuit 97A. If the APS signal, circuit 99B, indicates throttle is not
applied, then the CEC expects to see 0 volts at the IVS circuit 97A. The timing process is critical between
the APS and the IVS sensors. For this reason, it is very difficult to determine if the APS/IVS assembly is
working properly using a volt-ohmmeter.

2.3. BAROMETRIC AIR PRESSURE (BAP) SENSOR

The Barometric Air Pressure sensor (BAP) is a variable capacitance sensor which produces a linear analog
voltage signal that varies with altitude. The BAP signal is used by the CEC to adjust timing and fuel quantity, to
optimize engine operation and control smoke throughout all altitude conditions.

The CEC (379) sends a regulated 5 volt signal from CEC (379) on circuit 97U, through the black CEC module
connector (379), circuit 97U, engine connector (190), circuit 97U to a splice, and circuit 97BL to BAP sensor
(1160). The BAP sensor (1160) returns a variable voltage signal (represents atmospheric pressure) on circuit
97CD, connector (190) and circuit 97CD to the CEC (379). The BAP sensor (1160) is grounded by circuit
97Z/97W, connector (190), circuit 97BW to the CEC (379) signal ground.

2.4. AIR TEMPERATURE SENSOR (ATS)

The ambient Air Temperature Sensor (ATS) is a thermistor type sensor that has a variable resistance which
changes when exposed to different temperatures. The CEC measures the signal from the sensor and uses the
data to adjust timing and fuel rate to limit smoke emissions in cold weather starting.

The CEC module connector (379) sends a regulated 5 volt reference signal through circuit 97AX to the
Air Temperature Sensor (463). As the temperature changes, the sensor changes resistance and provides
the CEC with an air temperature signal voltage. The sensor is grounded through circuit 97BU/97BW to
the CEC signal ground.

2.5. ATA DATA LINK CONNECTOR

The six pin ATA data link connector (37) allows an electronic service tool (EST) to communicate with the ECM.
The data link carries serial data transmissions between the ECM and the electronic service tool, and between
the ECM and the speedo/tachometer cluster. Thus, the ECM provides vehicle and engine information to
the speedo/tachometer, and the EST.

The ATA data link connector (137), which is located on the left instrument panel, has circuits in four of the
six cavities. The data link circuits are a twisted wire pair because twisting the wires helps shield them from
interference. The circuits are as follows:

A. Circuit 98X(+) is the positive data link connection, and it is fed by the positive data link connector
(514), circuit 98(+), connector (190), and circuit 98(+) coming from the CEC module connector
(379).

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B. Circuit 98B(-) is the negative data link connection, and it is fed by the negative data link connector
(515), circuit 98C(-), connector (190), and circuit 98C(-) coming from the ECM CEC module
connector (379).
C. Circuit 97DL is a 12 volt feed and is fed from the battery adapter (497), circuit 14DLF, and 5A fuse
F10–D. Thus, it provides power for the electronic service tool.
D. Circuit 11–GR is connected to ground adapter (453), and provides a ground for the electronic
service tool.

2.6. DIAGNOSTIC ON/OFF SWITCH

A lighted diagnostic on/off switch is provided for on-board diagnostics. The switch is connector to ground
adapter (453). Moving the switch to the on position, closing the switch, applies the ground to circuit 98,
connector (190), and circuit 98 to the CEC module connector (379). This tells the ECM that the diagnostic
on/off switch has been turned on. Thus, the ECM will switch modes to display fault codes or the absence of
codes by flashing the engine warning light and the stop engine light.

2.7. CRUISE CONTROL/PTO SYSTEM

The Cruise/PTO system feature controls engine and vehicle speed using automotive style set/coast,
resume/accel., on/off switches and is controlled by the CEC. Speed control is disabled when the off switch is
depressed, the brake is applied, the clutch pedal is depressed or an automatic transmission is placed in neutral.

The cruise control switches and circuitry are also used for in-cab control of preset, variable, and mobile PTO
operation applications and required programming of the engine CEC.

Power is supplied to the lighted cruise control on/off switch (391) through I1 ignition adapter, circuit 13AA, fuse
F-10C, circuit 97DS and circuit 97AD. When the on/off switch is in the on position, power is supplied through
circuit 97CF, circuit 97CF, dash connector (190) and circuit 97CF to CEC (379). This enables the cruise control.

The lighted cruise set/resume (436) is a momentary switch. This switch receives 12 volts on circuits 97CA and
97CF from the cruise on/off switch (435) when it is in the on position. The cruise selector switch sends 12 volts
from the switch on circuit 97DJ, connector (190), and circuit 97DJ to CEC module connector (379) terminal 32
while in the set position. In the resume position, the switch sends 12 volts by way of circuit 97DK, connector
(190), and circuit 97DK to the ECM CEC module connector (379) terminal 22. If the cruise control speed has
not been engaged, momentarily depressing the switch causes the CEC to resume the last engine RPM setting.
If the cruise control is already engaged, momentarily depressing the resume/accel portion of the switch will
cause the engine RPM and speed to increase in small incremental amounts until the desired speed is reached.

For information on remote PTO control for body builder applications, refer to Miscellaneous Information
in CT-471 Body Builder Book.

2.8. CLUTCH SWITCH

The clutch pedal switch supplies the Driveline Disengaged Signal (DDS) to the CEC and the service brake
switches supply a Brake Normally Open (BNO) and Brake Normally Closed (BNC) signal to the CEC. These
signals indicate pedal positions and are used by the CEC in operating the Cruise/PTO control system.

The clutch switch (294) is a normally open (N.O.) switch that is adjusted so that its contacts are closed when
the clutch pedal is in the released position. Depressing the clutch pedal causes the switch contacts to open.

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Twelve (12) volts is supplied to connector (294) terminal B from I1 ign. adapter (494) through circuit 13BBB,
fuse F-10A, circuit 47A and circuit 97. When the switch is closed 12 volts is applied on circuit 97A through
connector (190) to CEC (379).

2.9. COOLANT LEVEL PROBE

The low coolant level probe is connected through connector (400–A) and circuit 34B to CEC module connector
(379). A signal from the ECM is sent to the probe on this circuit. The other side of the probe is connected
to chassis ground. When coolant level is below the probe, the circuit resistance changes, indicating to the
ECM that the coolant level is below the critical level.

2.10. VEHICLE SPEED SENSOR (VSS)

The Vehicle Speed Sensor (VSS) provides vehicle speed and engine RPM signals to the CEC. This information
is also used by the CEC to control the Cruise/PTO system.

Two types of sensors are available. The threaded (adjustable) sensor is used on most transmissions. A new
push-in style sensor (nonadjustable) is used on some transmissions.

2.11. SERVICE BRAKE SWITCH

The service brake switch (141) is a normally closed (N.C.) air operated switch. Its contacts are closed when
the brakes are not applied, and its contacts open up when the brakes are applied. One terminal of the service
brake switch (141) is connected to circuit 97NM, connector (190), circuit 97NM and the ECM (379). The other
terminal of the switch is connected to 12 volts by way of circuits 97AL and 97–DT to fuse F-10B.

2.12. ANTILOCK BRAKE INTERFACE

If the vehicle is equipped with antilock brakes, information is shared with the ABS controller module over the
ATA data link. Circuits 98K(-) and 97J(+) from the ABS controller connector to connector (282) and terminate
at data link neg. (515) and data link pos. (514).

With the cruise control on/off switch in the on position, power is also applied from the switch to the cruise
set/resume switch (392) through circuit 97CA. Momentarily depressing the set portion of this switch supplies a
12 volt signal to the CEC through circuit 97DA, dash connector (190), and circuit 97DH/7DJ. This engages the
cruise control and causes the CEC to maintain the current engine RPM. If the cruise control speed is already
set, depressing the switch in the set position causes the engine RPM to decrease until the switch is released.

With the cruise control on/off switch (391) in the on position, depressing the resume/accel portion of the
set/resume switch (392) supplies a 12 volt signal to the CEC through circuit 97DE, dash connector (190) and
circuit 97DE/97DK. If the cruise control speed has not been engaged, momentarily depressing the switch
causes the CEC to resume the last engine RPM setting. If the cruise control is already engaged, momentarily
depressing the resume/accel portion of the switch will cause the engine RPM and speed to increase in small
incremental amounts until the desired speed is reached.

The cruise control switches and circuitry are also used for in-cab control of preset, variable, and mobile PTO
operation applications and required programming of the engine CEC.

2.13. ENGINE BRAKE

On vehicles equipped with compression braking, switch (434) will turn the engine brake on or off. Switch (433)
will determine how many cylinders are used for braking by putting resistances from the resistor printed circuit

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board (390) in parallel. The CEC senses the voltage drop, across the parallel resistance, through (390)
and will control the engine accordingly.

The engine brake relay (286) disables engine braking when the ABS is active.

When engine brake on/off switch (434) is on and the engine brake relay is not energized, a ground is sent from
G1 ground adapter (453) on circuit 24–GA, 24AN and 24AT to terminals 2 and 5 of engine brake on/off switch
(434). When engine brake select switch (434) is on, ground will be available at terminals 3 and 6 of the switch.
5 volts from CEC connector (379) will be applied to resistor printed circuit board (390), terminal F. This voltage
will drop across a 2.2K ohm resistor (which may be selected in parallel with other resistors).

When engine brake select switch (433) is in the 1 position, only the 2.2k ohm resistor connected to terminal D
in the printed circuit board (390) will affect the voltage drop in the circuit. This will signal the CEC to select
compression braking on two cylinders of the engine.

When engine brake select switch (433) is in the 2 position, ground from (434) is supplied from terminal 3,
on circuit 24AD, to resistor printed circuit board (390) terminal C. 5 volts from CEC connector (379) will be
applied to resistor printed circuit board (390). The voltage drop across the parallel resistance between the
2.2K ohm and the 680 ohm resistor of printed circuit board (390) will signal the CEC to engage compression
braking on four cylinders of the engine.

When engine brake select switch (433) is in the 3 position, ground from (434) is supplied from terminal 3, on
circuit 24AD, through switch (433), contacts 6, 2 & 3 to resistor printed circuit board (390) terminals B and C. 5
volts from CEC connector (379) will be applied to resistor printed circuit board (390). The voltage drop across
the parallel resistance between the 2.2K ohm, the 680 ohm and the 121 ohm resistor of printed circuit board
(390) will signal the CEC to engage compression braking on all six cylinders of the engine.

3. TROUBLESHOOTING
A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Check any light or indicator lamp filaments that are suspected of being open (burned out). This is
done to avoid unnecessary extensive circuit checks.
C. Inspect all connectors for loose or damaged pins, wires, etc. Refer to TEST EQUIPMENT AND
CONNECTOR REPAIR section in GROUP 08 — ELECTRICAL in the CTS-5000 Master Service
Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit, by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not
covered in detail. It is assumed that the technician knows to check for a malfunctioning switch,
relay, or solenoid.

3.1. DETERMINING FAULT CODES

Refer to Engine/Vehicle Manual EGES-175 for detailed directions on reading fault codes.

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The EZ-Tech™ or PRO-LINK 9000® electronic service tools (EST) can be used to identify logged fault codes.
Refer to the EST manual for operating instructions.

The Serv/Check Engine and Warn Engine lights can be used to read fault codes by following the procedure
following.

Reading Flash Codes

KEY ON — ENGINE OFF PROCEDURE

NOTE – All International flash codes are three digit numbers.

1. Hold in the diagnostic on/off button and turn the key to the on position. Release the diagnostic button.
Do not start the vehicle.

2. The Serv/Check Engine light will FLASH one time. This indicates the beginning of active fault codes.

3. The Warn Engine light will FLASH repeatedly signalling the active fault codes. The number of flashes
should be counted in sequence.

4. At the end of each digit of the code there will be a short pause.

5. After each active code is displayed the Serv/Check Engine light will FLASH once to indicate the next code.

6. Once all active codes have been displayed, the Serv/Check Engine light will FLASH twice to indicate the
beginning of the inactive codes.

7. Inactive codes will be displayed in the same manner as active codes.

8. Once the inactive codes have been displayed, the Serv/Check Engine light will FLASH three times to
indicate that all stored codes have been displayed.

Refer to the directions in Engine/Vehicle Manual EGES-175.

If the diagnostics indicate that a circuit external to the engine is suspect, use the diagnostic tables included in
this section for a step-by-step procedure. Refer to the appropriate circuit diagram for International I6 HEUI
— ENGINES in CTS-5298 or S08225.

3.2. IMPORTANT STEPS BEFORE TESTING

1. Gather information by talking to the driver if possible. Try to determine the exact symptoms by gathering
relevant information:
a. What happened, and when?
b. Under what conditions?
c. When did the symptoms begin?
d. What else occurred at that time?

2. Verify the problem. Is the complaint due to misunderstood customer selected parameters? Use an EST
to review customer selected parameters.

3. Check for and record any logged fault codes.

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a. Do the logged codes correlate to probable causes?

4. Were the codes logged about the same time as the symptoms appeared? Were the codes logged
repeatedly?

5. Are the logged codes related to other symptoms? Do they have a common cause?

6. Avoid preconceived ideas! Eliminate any non-electrical causes for the problem first (contaminated
fuel, clogged air filters, etc.).

3.3. INSPECTING ELECTRICAL CONNECTORS

Visual Inspection

The troubleshooting guide requires checking specific connectors. Use the following steps to determine if
the connector is causing the problem. If a defective condition is found, make the necessary corrections
and continue the process.

1. Check the connector lock mechanism or retaining screw. Make sure the connector is capable of
properly locking the connector together.

2. Perform a 10 pound pull-test on each terminal/wire in the connector. Each terminal/wire assembly
should easily withstand 10 pounds of pull and remain in the connector. This test determines (A) if the
wire is properly in the terminal and (B) if the terminal is properly inserted into the connector. Correct
any defects noted.

3. Visually inspect wiring. Inspect for worn or damaged wires. Check for pinched or damaged harness.

4. Visually inspect connectors. Verify that pins and sockets are free of corrosion, dirt or any other
contaminants, and damage. Verify correct alignment and location of terminals in the connector.

5. Check individual pins and sockets. This is especially important with an intermittent symptom. Using a
new pin, insert the pin into each socket, one at a time, checking for a good grip on the pin by the socket.
Repeat for each pin on the mating side of the connector, using a new female terminal for the test.

6. Inspect Engine Ground Stud. Inspect this ground and other related grounds for clean, tight connections
that are free of corrosion and/or other defective conditions.

Performing Electrical Tests at CEC Module Connector (379)

CEC module connector (379) mates with the black ECM connector. This is a 60–pin connector, with the
International side having female terminals (sockets) and the ECM side having pins.

NOTE – No tests in this manual require testing “into” the black ECM connector.

When testing the chassis side of CEC module connector (379), never insert meter probes into the sockets,
as the probes will damage the sockets.Always use breakout box (ZTSE-4445) as described in International
Engine/Vehicle Manual EGES-175.

Replacing International Components

When replacing electrical switches, connectors (including pins and sockets), relays or other components, use
only approved International replacement parts. Many of the switches have gold or silver plated contacts and

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some of the connectors have gold plated terminals. By using correct replacement parts, you maintain the
design integrity of the system.

All of the relays and other solenoids installed by International are suppressed to prevent voltage spikes from
damaging electrical components. Again, use only International replacements for these components.

3.4. TESTING HELLA RELAY

International circuits use suppressed Hella relays for controlling power to load devices. The suppression
feature (a resistor circuit parallel to the relay coil) prevents voltage spikes from damaging electronic
components in the vehicle. These relays must be replaced by approved International parts.

The part number and relay circuit diagram are embossed on the relay body. The terminals are numbered on
the relay in the same manner as in the circuit diagrams.

Relay Test Procedure

1. With relay removed, measure resistance between terminals 30 and 87A. If resistance is less than 5
ohms, go to step 2; otherwise replace the relay.

2. Measure resistance between terminals 30 and 87. If resistance is 100K ohms or more, go to step 3;
otherwise replace the relay.

3. Using 12V battery source and test leads, connect (+) lead to terminal 85 and (-) lead to terminal 86. If relay
energizes with an audible click sound, go to step 4; otherwise replace the relay.

4. While relay is energized, measure resistance between terminals 30 and 87. If resistance is less than 5
ohms, go to step 5; otherwise replace the relay.

5. While relay is energized, measure resistance between terminals 30 and 87A. If resistance is 100K or
more, the relay is good; otherwise replace relay.

3.5. CEC POWER AND GROUND SYSTEM CIRCUITRY

Table 118 CEC Power and Ground System Circuitry
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off/ Disconnect black CEC (379), cavity 12 ± 1.5 Go to Go to next step.
On module connector (379). 24, 97CR to volts. Step 6.
Turn key on and at cavity gnd.
24, measure voltage from
circuit 97CR to ground.
2. Off Remove fuse F10-C and F10-C <1 ohm. Go to Locate cause of
check for open condition. next overload condition,
step. then repair. Replace
fuse.
3. On At F10-C fuse cavity F10-C, 12 ± 1.5 Go to Locate cause of low
A, check voltage from cavity A, volts. next or no voltage in circuit
circuit 13AA to ground. 13AA to step. 13AA, then repair.
Re-install fuse. ground.

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Table 118 CEC Power and Ground System Circuitry (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off/ Disconnect bulkhead (190), cavity 12 ± 1.5 Go to Locate cause of low
On connector (190). Turn V, 97CR to volts. next or no voltage in circuit
key on and at cavity V, ground. step. 97CR, then repair.
measure voltage from
circuit 97CR to ground.
5. Off Locate cause of low If
or no voltage in circuit condition
97CR between (190) and persists,
CEC connector (379). go to next
Reconnect connectors. step.
6. Off Remove CEC power (396), cavity 12 ± 1.5 Go to Go to next step.
relay (396). At socket 1/E, 14B to volts. Step 11.
cavity 1/E, measure ground.
voltage from circuit 14B
to ground.
7. Off Remove 40A power Fuse holder, <1 ohm. Go to Locate cause of
module fuse holder from 40A fuse. next overload condition,
between circuits 14A and step. then repair. Replace
14B, and check for open fuse.
condition.
8. Off At fuse holder, measure Fuse holder, 12 ± 1.5 Go to Locate cause of low
voltage from circuit 14A 14A to volts. next or no voltage in circuit
to ground. Re-install ground. step. 14A, then repair.
fuse.
9. Off Disconnect (490), 14B 12 ± 1.5 Go to Locate cause of low
battery/engine harness to ground. volts. next or no voltage in circuit
connector (490). At step. 14B, then repair.
circuit 14B, check voltage
to ground.
10. Off Locate cause of low If
or no voltage in circuit condition
14B between (490) and persists,
CEC power relay (396), go to next
then repair. Reconnect step.
connectors.
11. Off At relay (396) socket (396), cavity 12 ± 1.5 Go to Go to next step.
cavity A/5, measure A/5, 97CT to volts. Step
voltage from circuit 97CT ground. 16.
to ground.
12. Off Remove fuse F10B and F10B <1 ohm. Go to Locate cause of
check for open condition. next overload condition,
step. then repair. Replace
fuse.

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Table 118 CEC Power and Ground System Circuitry (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
13. Off At F10B fuse cavity A, F10B, cavity 12 ± 1.5 Go to Locate cause of low
measure voltage from A, 14B to volts. next or no voltage in circuit
circuit 14B, to ground. ground. step. 14B, then repair.
Re-install fuse.
14. Off/ Disconnect bulkhead (190), cavity 12 ± 1.5 Go to Locate cause of low
On connector (190). Turn F, 97CT to volts. next or no voltage in circuit
key on and at cavity F, ground. step. 97CT, then repair.
measure voltage from
circuit 97CT to ground.
15. Off Locate cause of low or
no voltage in circuit 97CT
between (190) and CEC
power relay (396), then
repair.
16. Off Bench test CEC power Relay (396) Relay Go to Replace CEC power
relay (396). Refer to tests next relay.
Testing Hella Relay. good. step.
17. On Measure resistance of (396), cavity <1 ohm. Go to Locate open or poor
circuit 97AH between B/2 ,to (379), next connection in circuit
relay (396), socket cavity cavity 25. step. 97AH, then repair.
B/2, and CEC module
connector (379), cavity
25.
18. Off Measure resistance of (396), cavity <1 ohm. Go to Locate open or
circuits between relay C/4, to next poor connection in
(396), socket cavity (379), cavity step. circuits 97CM/97CL,
C/4 and CEC module 21, 22, 41. 97CM/97CK, or
connector (379), cavity 97CM/97AL, then
21, 22, and 41. repair.
19. Off At CEC module (379), cavity <5 ohms. Go to Go to next step.
connector (379), measure 1, 2, 23, & 42 Step
resistance of circuits at to ground. 22.
cavities 1, 2, 23, and 42
to ground.
20. Off Disconnect battery (490), cavity <1 ohm. Go to Locate open or poor
harness connector (490). B, 11-G to next connection in circuit
At cavity B, measure ground. step. 11-G to negative battery
existence of circuit 11-G terminal, then repair.
to ground.

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Table 118 CEC Power and Ground System Circuitry (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
21. Off Locate open or
poor connection in
circuits 11-G/11-GX,
11-G/11-GW,
11-G/11-GY, or
11-G/11-GZ, then repair.
Go to next step.
22. Off Reconnect connectors.
Power and ground
system circuits check
good.

3.6. ACCELERATOR (APS/IVS), BAROMETRIC AIR PRESSURE (BAP) AND AMBIENT

AIR TEMPERATURE SENSOR SYSTEMS (ATS)
Table 119 Accelerator (APS/IVS), Barometric Air Pressure (BAP) and Ambient Air Temperature Sensor
Systems (ATS)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Is a fault code present for Go to Go to Step 10.
APS/IVS sensor/switch? next
step.
2. Off Remove and check fuse F10A <1 ohm. Go to Locate cause of
F10A for open condition. next overload condition,
step. then repair. Replace
fuse.
3. On At fuse F10A, measure F10A, cavity 12 ± 1.5 Go to Locate cause of low or
voltage from cavity A, A, 13BB to volts. next no voltage in circuits
circuit 13BB to ground. ground. page. 13BB or I1 Ignition
Re-install fuse. Adapter (494), then
repair.
4. On Disconnect APS/IVS (267) cavity 12 ± 1.5 Go to Locate cause of low
connector (267) and at F, 99E to volts. next or no voltage in circuit
cavity F, measure voltage ground. step. 99E, then repair.
from circuit 99E to ground.
5. Off At (267), install jumper (379), cavity <1 ohm. Go to Locate open or poor
from cavity A, circuit 99A to 8, 99B to next connection in circuit
ground. Disconnect CEC ground. step. 99B or bulkhead
connector (379). At cavity connector (190), then
8, measure resistance from repair.
cir. 99B to ground.

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Table 119 Accelerator (APS/IVS), Barometric Air Pressure (BAP) and Ambient Air Temperature Sensor
Systems (ATS) (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
6. Off At (267), move jumper to (379), cavity <1 ohm. Go to Locate open or poor
cavity B, circuit 99B and 11, 97BW to next connection in circuit
ground. At (379) cavity 11, ground. step. 97BW/97W, bulkhead
measure resistance of cir. connector (190), or
97BW to ground. cir. 97W/99B, then
repair.
7. Off At (267), move jumper (379), cavity <1 ohm. Go to Locate open or
to cavity C, cir. 99C and 3, 97U to next poor connection in
ground. At (379) cavity ground. step. circuit 97U, bulkhead
3, measure resistance of connector (90), or cir.
circuit 97U to ground. 97U/99C, then repair.
8. Off At (267), move jumper to (379), cavity <1 ohm. Go to Locate open or poor
cavity D, circuit 99D and 27, 99D to next connection in circuit
ground. At (379) cavity ground. step. 99D, or bulkhead
27, measure resistance of connector (190), then
circuit 99D to ground. repair.
9. Off Remove jumper and End test. Replace APS/IVS. If
reconnect connectors. problem persists,
APS/IVS circuits check refer to Engine
good? Is problem Diagnostic Manuals.
corrected?
10. Off Is a fault code present for Go to Go to Step 15.
BAP sensor? next
step.
11. Off Disconnect BAP sensor (379), cavity <1 ohm. Go to Locate open or poor
connector (1160). Install 11, 97BW to next connection in circuit
jumper wire from cavity ground. step. 97Z/97W, bulkhead
1, cir. 97Z to ground. connector (190), or
Disconnect CEC module circuit 97W/97BW,
connector (379). At cavity then repair.
11, measure resistance of
cir. 97BW to ground.
12. Off At (1160), move jumper (379), cavity <1 ohm Go to Locate open or
wire to cavity 2, circuit 3, 97U to next poor connection in
97BL and ground. At ground. step. circuit 97U, bulkhead
(379) cavity 3, measure connector (190), or
resistance of circuit 97U to circuit 97U/97Bl, then
ground. repair.
13. Off At (1160), move jumper (379), cavity <1 ohm. Go to Locate open or poor
wire to cavity 3, circuit 97D 29, 97CD to next connection in circuit
and ground. At (379) cavity ground. step. 97CD or bulkhead
29, measure resistance of connector (190), then
circuit 97CD to ground. repair.

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Table 119 Accelerator (APS/IVS), Barometric Air Pressure (BAP) and Ambient Air Temperature Sensor
Systems (ATS) (cont.)
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
14. Off Remove jumper and End test. Replace BAP sensor.
reconnect connectors. If problem persists,
BAP system circuits refer to Engine
check good? Is problem Diagnostic Manuals.
corrected?
15. Off Is a fault code present for Go to End test.
the ATS system? next
step.
16. Off Disconnect ATS connector (379), cavity <1 ohm. Go to Locate open or poor
(463). Install jumper wire 12, 97AX to next connection in circuit
from cavity B, circuit 97AX ground. step. 97AX, then repair.
to ground. Disconnect
CEC module connector
(379). At cavity 12,
measure resistance from
circuit 97AX to ground.
17. Off At (463), move jumper to (379), cavity <1 ohm. Go to Locate open or poor
cavity A, circuit 97BU and 11, 97BW to next connection in circuit
ground. At (379), cavity ground. step. 97BW/7BU, then
11, measure resistance of repair.
circuit 97BW to ground.
18. Off Remove jumper and End test. Replace ATS. If
reconnect connectors. problem persists,
ATS system circuits refer to Engine
check good? Is problem Diagnostic Manuals.
corrected?

3.7. DIAGNOSTIC CONNECTOR (137) AND DATA LINK CIRCUITS

Testing Diagnostic Connector Power and Ground Circuits

Table 120 Testing Diagnostic Connector Power and Ground Circuits

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
1. Off Remove and check 5A F10D <1 ohm. Go to next Locate cause of
fuse F10D for open step. overload condition,
condition. Is fuse open? then repair.
Replace the fuse.

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Table 120 Testing Diagnostic Connector Power and Ground Circuits (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
2. On Re-install fuse F10D. (137), 97DL 12 ± 1.5 Go to next Locate cause of no
At connector (137), to ground. volts. step. or low voltage in
measure voltage from circuit 97DL, then
circuit 97DL to ground. repair.
3. On At connector (137), (137) 12 ± 1.5 Power Locate open or
measure voltage between between volts. and gnd. poor connection
circuit 97DL and circuit 97DL and circuits in circuit 11-GR
11-GR. 11-GR. to diag- or ground adapter
nostic (43), then repair.
conn.
(137)
check
good.

3.8. TESTING DIAGNOSTIC CONNECTOR AND SPEEDOMETER/TACHOMETER

POSITIVE AND NEGATIVE DATA LINK CIRCUITS
NOTE – A multimeter cannot be used to measure the voltage of the signal on these circuits.

Table 121 Testing Diagnostic Connector and Speedometer/Tachometer Positive and Negative Data
Link Circuits
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
1, Off Disconnect CEC (137), 98(+) >100K Go to next Locate short to
module connector (379) to ground. ohms. step. ground, then repair.
from ECM and (421)
from speedometer unit.
If other devices are
connected at data link
connectors (514) and
(515), disconnect them.
At connector (137)
measure resistance
from terminal A, circuit
98(+) to ground.
2. Off At connector (137) (137), >100K Go to next Locate short to
measure resistance 98B(-) to ohms step. ground, then repair.
from terminal B, circuit ground.
98B(-) to ground.
3. Off At connector (137), (137) >100K Go to next Locate short circuit
measure resistance between ohms. step. between circuits
between terminal 98(+) and connected to
A, circuit 98(+) and 98B(-). terminal A 98(+),
terminal B, circuit 47/48(+) and
98B(-). terminal B 98B(-),
47/48(-), then repair.

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Table 121 Testing Diagnostic Connector and Speedometer/Tachometer Positive and Negative Data
Link Circuits (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
4. Off At CEC module (137), 98(+) <5 Go to next Locate open or poor
connector (379), use to ground. ohms. step. connection in circuit
test lead to jumper 98(+) between
terminal 16, circuit connectors (514)
98A(+) to ground. and (137) or open
At connector (137) or poor connection
terminal A, circuit 98(+) in circuit 98A(+)
measure resistance to between connectors
ground. (514) and (379),
then repair.
5. Off With jumper still in (421), <5 Go to next Locate open or poor
place at terminal 16, 47/48(+) to ohms. step. connection in circuit
circuit 98A(+), measure ground. 47/48(+) between
resistance to ground connectors (421)
at circuit 47/48(+) and and (514), then
connector (421). repair.
6. Off At CEC module (137) <5 Go to next Locate open or poor
connector (379) use between ohms. step. connection in circuit
test lead to jumper 98(+) and 98B(-) between
terminal 16, circuit 98B(-). connectors (515)
98A(+) to terminal and (137), or open
17, circuit 98C(-). or poor connection
At connector (137) in circuit 98C(-)
measure resistance between connectors
between terminal (515) and (379),
A, circuit 98(+) and then repair.
terminal B, circuit
98B(-).
7. Off With jumper still in (421), <5 Locate open All data link circuits
place, at connector 47/48(-) to ohms. in circuit check good.
(421) measure ground. 47/48(-)
resistance between between
47/48(-) and ground. conn. (421)
and (515),
then repair.

3.9. VEHICLE SPEED SIGNAL

Adjustable VSS Adjustment: Turn sensor in until it bottoms out, then back off one full turn.

Construct test leads using terminals 1680205C1, short length of 16 gauge wire and alligator clips.

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WARNING – A jack must never be used alone to support vehicle. The jack may lower and
serious injury could result. Always support vehicle with floor jacks. Always block wheels to prevent
vehicle from moving.

WARNING – EXTREME CAUTION should be used to prevent personal injury resulting from
contact with rotating vehicle wheels when connecting.

Testing Vehicle Speed Sensor (303)

Table 122 Testing Vehicle Speed Sensor (303)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Inspect VSS for damage Go to next
and proper adjustment step.
before performing this
test.
2. Off Disconnect engine VSS, A to B. 600 Go to next Replace the
harness connector to 800 step. vehicle speed
(303) from VSS and ohms for sensor (VSS).
use test leads to measure adjustable
resistance between sensor.
terminal A and B of the 1500 to
sensor. 3500
ohms for
push- in
sensor.
3. Off Measure resistance to VSS, A and >100K Go to next Replace the
ground at both terminals B to ground. ohms. step. vehicle speed
(A and B) of the sensor. sensor (VSS).
4. Off VSS sensor output test: Go to next
This test checks for step.
proper AC voltage output
signal from the VSS
sensor. Improper sensor
adjustment will cause low,
erratic or no output.
5. Off Block front wheels and Go to next
place rear axles on floor step.
stands.

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Table 122 Testing Vehicle Speed Sensor (303) (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
6. Off Use AC voltmeter with Go to next
sufficient length leads to step.
avoid personal contact
with rotating vehicle
wheels during test.
Connect meter leads
to sensor test leads.
7. On Run engine at idle speed VSS, A to B. >2.0 volts The vehicle If sensor was
with transmission in high AC. speed properly adjusted,
gear. Measure voltage sensor replace the
across the two sensor checks sensor.
terminals. good.

Testing Vehicle Speed Sensor To ECM Circuits

Table 123 Testing Vehicle Speed Sensor To ECM Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connector (303), both >100K Go to next Locate short to
(303) from VSS and terminals to ohms. step. ground in circuit
(379) from the ECM. At ground. (47A or 47), then
connector (303) measure repair.
resistance to ground at
both terminals.
2. Off At (303) measure (303), >100K Go to next Locate short circuit
resistance between between ohms. step. between circuits 47
terminals. terminals. and 47A, between
connectors (303)
and (379), then
repair.
3. Off At CEC module connector (303), 47A <5 ohms. Go to next Locate open or poor
(379) use test lead to to ground. step. connection in circuit
jumper terminal 40 to 47A, then repair.
ground. At connector (303)
measure resistance to
ground, at circuit 47A.
4. Off At CEC module connector (303), 47 to <5 ohms. Vehicle Locate open or poor
(379) use test lead to ground. speed connection in circuit
jumper terminal 39 to circuits and 47, then repair.
ground. At connector (303) VSS check
measure resistance to good.
ground at circuit 47.

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3.10. CRUISE AND PTO CONTROLS

The EZ-Tech or Pro-Link Electronic Service Tool (EST) can be used to monitor system parameters relating
to Cruise Control operation. Use the EST to monitor operation of system switches, including the Cruise
On/Off, Set/Resume, service brake and clutch switch.

Testing Cruise On/Off Switch and Circuits

Table 124 Testing Vehicle Speed Sensor To ECM Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connector Across <2 ohms. Go to next Replace the switch.
(435) from cruise on/off cruise step
switch. With switch in the on/off
on position measure switch.
resistance between
terminals 5 and 6.
2. Off Disconnect CEC connector (435), <5 ohms. Go to next Locate open or poor
(379) from ECM. Measure 97AD to step. connection in circuit
the resistance between (379), 97AD or 97CR
connector (435), terminal 97CR. between connector
6 (circuit 97AD) and (379) (435) and (379),
terminal 24 (circuit [97CR]). then repair.
3. Off Measure the resistance (435) 97AE <5 ohms. Cruise Locate open or
between connector (435), to (379), on/off poor connection
terminal 5 (circuit 97AE) 97. switch and in circuit 97AE
and (379) terminal 35 circuits to or 97CF between
(circuit [97CF]). (379) check connectors (435)
good. and (379), then
repair.

Testing Cruise Set/Resume Switch and Circuits

Table 125 Testing Cruise Set/Resume Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
1. Off Remove connector (436) Set/ resume >100K Go to next Replace set/
from cruise set/resume switch, 2 to 1 ohms. step. resume switch.
switch. With switch in and 2 to 3.
neutral position, measure
resistance between switch
terminal 2 and terminals 1
and 3.
2. Off With switch in resume Set/ resume <2 ohms. Go to next Replace set/
position, measure switch, 1 to step. resume switch.
resistance between switch 2.
terminals 1 and 2.

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Table 125 Testing Cruise Set/Resume Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF
POINTS SPEC. SPEC.
3. Off With switch in set position, Set/ resume <2 ohms. Go to next Replace set/
measure resistance switch, 2 to step. resume switch.
between switch terminals 3.
2 and 3.
4. Off Disconnect CEC connector (436) circuit <5 ohms. Go to next Locate open or
(379) from ECM. Measure 97GB and step. poor connection
the resistance between (379) circuit in circuit 97GB or
connector (436) terminal 97CF. 97CF, then repair.
2 (circuit 97GB) and (379)
terminal 35 (circuit 97CF.
5. Off Measure the resistance (436), <5 ohms. Go to next Locate open or
between connector (436) terminal 3 step. poor connection
terminal 3 and (379) and (379) in circuit
terminal 32. terminal 32. 97DJ between
connectors (436)
and (379), then
repair.
6. Off Measure the resistance (436) <5 ohms. The set/ Locate open or
between connector (436) terminal 1 resume poor connection
terminal 1 and (379) and (379) switch and in circuit
terminal 31. terminal 31. circuits test 97DK between
good. connectors (436)
and (379), then
repair.

3.11. CLUTCH SWITCH (294)

Testing Clutch Switch and Circuits

NOTE – If the vehicle is equipped with an Allison transmission, this switch is replaced with a jumper
connection.

Table 126 Testing Clutch Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off At (294) disconnect clutch Clutch <2 ohms. Go to next If switch is not
switch lead from cab switch, A step. adjusted properly,
harness. With clutch to B. adjust and retest.
pedal released, measure (Refer to Adjusting
resistance across clutch Clutch Switch.) If
switch pigtail connector (A switch is adjusted
to B). Switch should read properly replace the
closed. switch.

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Table 126 Testing Clutch Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off Depress clutch pedal while Clutch >100K Go to next If switch is not
measuring resistance switch, A ohms. step. adjusted properly,
across clutch switch pigtail to B. adjust and retest
(294) terminal A to B. (refer to Adjusting
Clutch Switch). If
switch is adjusted
properly, replace
the switch.
3. On With ignition on measure (294), 12 ± 1.5 Go to next Locate cause of no
the voltage between clutch circuit 97 volts. step. or low voltage in
switch (294), circuit 97 to to ground. circuit 97 or 97AK,
ground. then repair.
4. Off Disconnect CEC module (294), <5 ohms. Go to next Locate open in
connector (379) from 97AH to step. circuit 97A, then
ECM. Measure resistance ground. repair.
between clutch switch
(294) terminal A (circuit
97A) and (379) terminal
26.
5. Off Measure resistance from (294), 97A >100K The clutch Locate short in
clutch switch (294) terminal to ground. ohms switch circuit 97A, then
A (circuit 97A) to ground. circuits repair.
check good.

Adjusting Clutch Switch

The clutch switch should be mounted so that the switch actuator makes contact with the clutch pedal arm when
the arm is depressed 0.5 inch at the point of actuator contact. The bracket can be bent forward or backward for
adjustment. An audible click (switch closing) should be heard when the pedal is released.

3.12. SERVICE BRAKE SWITCH (141)

Testing Service Brake Switch and Circuits

Table 127 Testing Service Brake Switch and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove connector (141) Brake >100K Go to next Replace the brake
from service brake switch. switch to volts. step. switch.
With brakes released, ground
measure resistance to at each
ground at each switch terminal.
terminal (not the harness
connector side).

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Table 127 Testing Service Brake Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off With (141) removed from Across <2 ohms. Go to next Replace the brake
service brake switch, and switch step. switch.
service brakes released, terminals.
measure resistance across
switch terminals.
3. Off With vehicle air pressure Across >100K Go to next Replace the brake
>80 PSI, apply service switch volts. step. switch.
brakes while measuring terminals.
resistance across the
brake switch terminals.
4. Off Disconnect CEC module (141), <5 ohms. Go to next Locate open or
connector (379) from ECM 97AL to step. poor connection
and do not reconnect (141) ground. condition in circuit
to switch. Use test lead 97NM between
to jumper CEC module connectors (141)
connector (279) terminal and (379), then
44 (circuit 97M) to ground. repair.
At brake switch (141),
measure resistance to
ground at circuit 97NM.
5. Off Measure resistance (141), >100K Go to next Locate short circuit
between brake switch 97NM to ohms. step. between circuit
(141) terminal C (circuits ground. 97NM and ground,
97NM and ground. then repair.
6. Off Measure resistance (379) <5 ohms. Go to next Locate open in
between CEC module terminal 44 step. circuit 97M or 97N
connector (379) terminal and 43. between (379)
44 and 43. terminals 44 and
43.
7. Off Measure the voltage (141), 12 ± 1.5 The brake Locate cause of no
between brake switch 97AL to volts. switch and or low voltage in
(141) terminal D (circuit ground. circuits circuit 97AL, then
97AL) and ground. check good. repair.

3.13. TESTING LOW COOLANT SENSOR AND CIRCUITS

Table 128 Testing Service Brake Switch and Circuits
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect (400) from Sensor <1 ohm. Go to next Replace open
the surge tank. Drain terminal step. sensor.
the coolant from the A and the
reservoir and remove probe tip.
the sensor. Measure
resistance between sensor

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Table 128 Testing Service Brake Switch and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
terminal A and the probe
tip.
2. Off Measure resistance Sensor >100 K Go to next Replace shorted
between sensor terminal B terminal ohms. step. sensor.
and the probe tip. B and the
probe tip.
3. Off Disconnect CEC (379) circuit >100K Go to next Locate short in
connector. (379) from 34B to ohms. step. circuit 34B, then
the ECM. Measure the ground. repair.
resistance from (379)
terminal 10 (circuit 34B) to
ground.
4. Off At (400-A) place a jumper (379) <5 ohms. Sensor and Locate open in
between circuit 34B terminal low coolant circuit 34B, then
and ground. Measure 10 (circuit circuits repair.
resistance from (379) 34B) to check good.
terminal 10 (circuit 34B) to ground.
ground.

3.14. ENGINE BRAKE CONTROLS

Testing Engine Brake Switches and Circuits

Table 129 Testing Engine Brake Switches and Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove engine brake Circuit <2 ohms. Go to next Locate open or poor
relay (286). At relay 24-GA to step. connection in circuit
socket, measure ground. 24-GA to ground.
resistance from circuit
24-GA to ground.
2. On Turn ignition on. At relay Circuit 12± 1.5 Go to next Locate cause of
socket, measure voltage 24AS and volts step. incorrect voltage on
between circuit 24AS and ground. circuit 24AS.
ground.
3. Off Bench check the engine Relay Re- install Replace engine
brake relay (286). Refer checks relay. Go to brake relay.
to Testing Hella Relay. good. next step.

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Table 129 Testing Engine Brake Switches and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off Remove connector Engine <2 ohms. Go to next Replace engine
(434) from on/off switch. brake step. brake on/off switch.
Use ohmmeter to test switch 5 to
the switch. In the on 6, as well
position, continuity should as 2 and 3.
be present between
terminals 5 and 6, as well
as 2 and 3.
5. Off Use ohmmeter to test the Engine >100K Go to next Replace engine
switch. In the off position, brake ohms. step. brake on/off switch.
no continuity should switch 5 to
be present between 6 as well as
terminals 5 and 6 or 2 2 and 3.
and 3.
6. Off At (434), measure (434), <5 ohms. Re-install Locate open or
resistance between terminal 2 (434). Go poor connection
terminal 2 and 5 to and 5 to to next step. in circuit(s) 24AN,
ground. ground. 24AT, or 24A, then
repair.
7. Off Remove connector (433) Engine <2 ohms. Go to next Replace engine
from engine brake select brake step. brake select switch.
switch. Use ohmmeter select
to test the switch. In the switch
3 position, continuity terminals
should be present 2, 5, 6, and
between terminals 2, 3.
6, and 3.
8. Off Use ohmmeter to test Engine <2 ohms. Go to next Replace engine
the switch. In the 1 brake step. brake select switch.
position, continuity should select
be present between switch
terminals 2 and 3. terminals
2 and 3.
9. Off Use ohmmeter to test Engine <2 ohms. Go to next Replace engine
the switch. In the 2 brake step. brake select switch.
position, continuity should select
be present between switch
terminals 2 and 6. terminals
2 and 6.
10. Off Place engine brake on/off (433), <2 ohms. Re-install Locate open in
switch (434) to the on circuit (433). Go circuit 24AD.
position. Measure the 24AD to to next step.
resistance from (433), ground.
circuit 24AD to ground.

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Table 129 Testing Engine Brake Switches and Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
11. Off Remove connector (390). (390) <2 ohms. Go to next Locate open in
Measure resistance terminal C step. circuit 24AF.
between (390) terminal C and (433)
and (433) terminal 2. terminal 2.
12. Off Measure resistance (390) <2 ohms. Go to next Locate open in
between (390) terminal B terminal B step. circuit 24AE.
and (433) terminal 3. and (433)
terminal 3.
13. Off Measure resistance (390) <2 ohms. Go to next Locate open in
between (390) terminal D terminal step. circuit 24AM.
and ground. D and
ground.
14. Off Measure resistance Terminal B 122 to Go to next Replace resistor
between printed circuit and F of 120 step. printed circuit
board terminal B and F of the circuit ohms. board.
the circuit board. board
15. Off Measure resistance Terminal C 714 to Go to next Replace resistor
between terminal C and and F of 646 step. printed circuit
F of the circuit board. the circuit ohms. board.
board
16. Off Measure resistance Terminal D 2310 Re-install Replace resistor
between terminal D and and F of to 2090 printed printed circuit
F of the circuit board. the circuit ohms. circuit board.
board board. Go
to next step.
17. Off Disconnect CEC module 24A <5 ohms. Go to next Locate open or
connector (379) from between step. poor connection in
CEC. Measure resistance (434) and circuit 24A between
of circuit 24 between (433). connectors (434)
connectors (390) terminal and (379), then
F and (379) terminal 13. repair.
18. Off Measure resistance (379) circuit >100K Engine Locate short in
between connectors 24 to ohms. brake circuit 24A between
(379) terminal 13 and ground. circuits connectors (434)
ground. check good. and (379), then
Consider repair.
replacing
the CEC.

4. COMPONENT LOCATIONS
(B1) Battery Stud. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . . Power Distribution Panel
(94) Back-Up Light Switch. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . . . . . On Transmission
(137) 6–Way Data Link Connector. . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(141) Service Brake Switch/Cruise Switch. . . . . . . . .. . . . . . Dash Panel, Left Side, Engine Side

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(190) Cab Overlay to Elect. Eng. Harn.. . . . . . . . . . . .. . . . . . Right Instrument Panel

(227) Fan Solenoid. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . ... . . . . . At Front of Engine
(228) Refrigerant Pressure Switch .. . .. . .. . . .. . .. . ... . . . . . On A/C Compressor
(229) Engine Oil Temp. Sender. . .. . .. . .. . .. . .. . .. . ... . . . . . Left Side of Engine
(190) Cab Overlay to Elect. Eng. Harn.. . . . . . . . . . . .. . . . . . Right Instrument Panel
(235) Transmission Oil Temp (Inline).. . . .. . . . .. . . .. .. . . . . . On Front of Transmission
(390) Resistor Printed Circuit Board. . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel, Taped to Cab Harness
(400–A) Low Coolant Level Switch. . . . . . . . . . . .. . . . . .. . . . . . To Engine Harness
(267) APS/IVS Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Electronic Foot (Gas) Pedal
(294) Clutch Switch Connector. . . . . . . . . . . . . . . . . . . . . .. . . . . . Near Clutch Switch
(303) Vehicle Speed Sensor. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . On Transmission
(379) CEC Module Connector. . . . . . . . . . . . . . . . . . . . . . .. . . . . . On Engine
(396) Module Power Relay On Engine. . .. . . .. . . . .. .. . . . . . On Bracket at Center of Dash, Engine Side
(490) ECM Power Conn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Battery Terminal Pigtail
(514) Data Link — Positive.. . . .. . . .. . . .. . . .. . . .. . . .. .. . . . . . Behind Instrument Panel/Behind Cluster
(515) Data Link — Negative.. .. .. .. . .. .. .. .. . .. .. .. ... . . . . . Behind Instrument Panel/Behind Cluster
(1160) BAP Sensor Connector. .. . .. . . .. . .. . .. . .. . . ... . . . . . Under Dash to Right of Ignition Switch
(1161) Ambient Air Temperature Sensor. . . . .. . . . .. .. . . . . . Air Intake Tube

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Figure 121 Engine Wiring, Cab

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400 10 INTERNATIONAL 530E I6 HEUI ENGINES

1. DASH PANEL (VIEWED FROM INSIDE ENGINE COMPARTMENT)

2. (141) BRAKE SWITCH
3. (640) STOP LIGHT SWITCH
4. (190) ELECTRONIC ENGINE CONNECTOR
5. RIGHT HAND DASH PANEL GROUND STUD
6. (3) ENGINE CONNECTOR
7. (2) CHASSIS HARNESS CONNECTOR
8. POWER DISTRIBUTION PANEL
9. SWITCHES
10. RIGHT GAUGE CLUSTER
11. SPEEDOMETER / TACHOMETER CLUSTER
12. LEFT GAUGE CLUSTER
13. (514) DATA LINK CONNECTOR
14. (515) DATA LINK CONNECTOR
15. (137) DATA LINK
16. CLUTCH SWITCH
17. FRONT END HARNESS CONNECTOR
18. THROTTLE PEDAL
19. (294) CLUTCH SWITCH CONNECTOR
20. (267) THROTTLE PEDAL CONNECTOR

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Figure 122 Engine Wiring, Dash Panel

1. (190) ELECTRONIC ENGINE CONNECTOR
2. RH DASH PANEL GROUND STUD
3. (2) CAB/ENGINE HARNESS CONNECTOR
4. MEGAFUSE
5. CIRCUIT 17C
6. CIRCUIT 17B
7. CIRCUIT 14A
8. CIRCUIT 14
9. START MAGNETIC SWITCH
10. CIRCUIT 17D
11. COOLANT LEVEL SENSOR
12. TO ENGINE HARNESS

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Figure 123 Engine Wiring

1. TO TRANSMISSION
2. CIRCUIT 14B & 11G
3. GROUND STUD
4. (379) ECM CONNECTOR
5. TO OTHER SIDE OF ENGINE
6. (1075) ENGINE FAN CONTROL CONNECTOR
7. AMBIENT AIR TEMPERATURE CONNECTOR
8. (249) LOW COOLANT SENDER CONNECTOR
9. TO ENGINE WIRING AT DASH PANEL

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Figure 124 Engine Wiring

1. TO OTHER SIDE OF ENGINE
2. CIRCUIT 77C TO COMPRESSOR CLUTCH
3. CIRCUIT 23A AND 23B TO REFRIGERANT PRESSURE SWITCH
4. ALTERNATOR

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Figure 125 Engine Wiring, Starter Motor

1. CIRCUIT 14FL
2. CIRCUIT 17C
3. CIRCUIT 11-GU
4. TO ENGINE BLOCK
5. CIRCUIT 11-GA
6. CIRCUIT 11-GL

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Figure 126 Engine Wiring, Alternator Effects

1. CIRCUIT 1A
2. ENGINE HARNESS
3. CIRCUIT 11-GL
4. CIRCUIT 2

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Figure 127 Engine Wiring, Transmission Effects

1. (94) BACK–UP LIGHT SWITCH CONNECTOR
2. TO ENGINE HARNESS

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Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .409
1.1. AIR DRYER. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .409
1.2. TRUCK BODY CONNECTION. . . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .409
1.3. TRAILER CONNECTION. . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .409
1.4. FOUR WHEEL TRAILER CONNECTION. .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .409
1.5. TWO SPEED AXLE WIRING. . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . .409

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .410
2.1. AIR DRYER. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .410
2.2. TRUCK BODY CONNECTION. . . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .410
2.3. TRAILER CONNECTION. . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .410
Red Terminal - Stop Light. . . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .. . . . . .410
Yellow and Green Terminals - Turn And Hazard Lights. . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .410
Brown Terminal - Tail Light. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .410
Black Terminal - Marker Light . . .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . ..411
Blue Terminal - Trailer ABS.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..411
White Terminal - Trailer Socket Ground. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. .. . .. ..411
2.4. TRAILER CONNECTION FOUR WHEEL TRAILER — FRAME MOUNTED. . . . . . . . . . . . . . . . . . . . .411
Red Terminal — Stop Light.. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. ..411
Yellow and Green Terminals — Turn and Hazard Lights. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. .411
Brown Terminal — Tail Light. .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. .412
Black Terminal — Marker Light.. . .. .. .. . .. .. .. . .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. . .. .. .. . .. .. .. . .. .. .412
Blue Terminal — Trailer Auxiliary Power. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .412
White Terminal —Trailer Socket Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .412
Two Speed Axle Wiring. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .412

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .412
3.1. AIR DRYER. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .413
3.2. TRUCK BODY CONNECTION. . . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . .414
Testing Marker Lights Power Feed. . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . .414
Testing Ground Circuit.. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. .415
3.3. TRAILER CONNECTION. . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . . . . . .416
Testing Stop Light Circuit. . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .416
Testing Turn and Hazard Circuits. .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .417
Testing Tail Light Circuit. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. .418
Testing Marker Light Circuit. . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .418
Testing ABS Trailer Circuit. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .419
Testing Trailer Socket Ground Circuit.. .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. .420
3.4. TWO SPEED AXLE WIRING. . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . .421

4. COMPONENT LOCATIONS. .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .422

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1. DESCRIPTION
1.1. AIR DRYER
The air dryer collects and removes moisture and contaminants from the vehicle’s compressed air system
before the moisture reaches the first air reservoir. The heater and thermoswitch assembly, located in the air
dryer, prevents freeze-up in the purge drain valve during cold weather operation.

1.2. TRUCK BODY CONNECTION

The truck body connection provides power and ground paths for the marker lights to be installed along with
the body builder’s body assembly. An additional auxiliary power circuit and switch are also provided for
compartment lights etc.

1.3. TRAILER CONNECTION

The 7-way trailer socket (112) connects the tractor and trailer wiring for operation of stop, tail, turn and hazard
signal lights, and tail and clearance lights. Additionally, the trailer socket includes a circuit that provides voltage
from the (B1) battery stud to power the trailer antilock brake system. The trailer socket terminals are color
coded as shown in Trailer Socket Figure.

1.4. FOUR WHEEL TRAILER CONNECTION

The 7–way four wheel trailer socket (112) connects the truck and trailer wiring for operation of stop, tail, turn
and hazard signal lights and tail and clearance lights. Additionally, the trailer socket includes a circuit that
provides voltage from the (B1) battery stud to power the trailer antilock brake system. The trailer socket
terminals are color coded as shown in Trailer Socket Figure.

Figure 128 Trailer Socket (112)

1.5. TWO SPEED AXLE WIRING

The two speed axle wiring provides a voltage signal to the speedometer/tachometer module so that the
speedometer and tachometer will correctly measure speed and mileage when the rear axle assembly shifts
to a different gear ratio.

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2. OPERATION
2.1. AIR DRYER
Turning the key switch on applies ignition power on circuit 13AH to energize the air dryer control relay (146).
With the relay energized, battery voltage on circuit 14AD, fuse F10–A and circuit 39A from battery adapter (B1)
passes through the relay normally open (N.O.) contacts (30 to 87). It then flows out the relay on circuit 39B,
through connector (1), and is applied to the air dryer assembly’s electrical pigtail.

The air dryer thermocouple closes at less than 50°F/10°C, applying battery power to the heater element
located in the air dryer assembly. The air dryer control relay ground circuit 13-GAD is grounded through ground
adapter (455), then through 11-GE to ground stud at left dash panel.

2.2. TRUCK BODY CONNECTION

The truck body junction block, located at the rear of the cab, provides a ground at terminal and a marker light
voltage from the marker light relay (463-R8) at terminal 2.

Terminal 1 of the truck body junction block is grounded through circuit 11-GM to trailer socket ground inside the
cab, 11-GN and 11-GI to ground stud at left dash panel.

Turning the headlights to park or on energizes the trailer marker lights relay. This delivers battery power from
(B2) stud through circuit 14H, 14E, fuse F3-A, circuit 58D, relay (463-R8), circuit 58R, and 58S to terminal 2 of
the truck body junction block.

2.3. TRAILER CONNECTION

Red Terminal - Stop Light

When the tractor brakes are applied, the vehicle stop light switch supplies power through circuit 70A/70D to
energize the stop light relay (464)/R10. With the stop light relay energized, power from the (B1) battery stud,
circuit 14K/14F, fuse F7-D, and circuit 70E is sent through the normally open contacts of stop light relay on
circuit 70C, conn. (922), conn. (925), and circuit 70C to trailer socket conn. (112) at the red terminal.

Yellow and Green Terminals - Turn And Hazard Lights

In the LEFT TURN mode (or hazard switch on), power flows from (B1) battery stud through circuit 14K, 14R,
fuse F2-D, circuit 55, flasher, circuits 14BK, 55A and 16BK to turn signal switch. From the switch it flows
through circuit 56E to energize relay (464)/R11. With the left turn relay energized, power flows from (B1)
battery stud through circuits 14K, 14L, fuse F7-B, circuit 56H, through normally open contacts of left turn relay,
and circuit 56C conn. (923), conn. (926) and circuit 56D to the trailer socket (112) yellow terminal.

In the RIGHT TURN mode (or hazard switch on), power flows from (B1) battery stud through circuits 14K,
14R, fuse F2-D, circuit 55, flasher, circuits 14BK, 55A and 16BK to turn signal switch. From the switch it flows
through circuit 57E to energize relay (464)/R12. With the right turn relay energized, power flows from (B1)
battery stud through circuits 14K, 14L, fuse F7-C, circuit 57H, through normally open contacts of right turn
relay, and circuit 57C conn. (923), conn. (926) and circuit 57D to the trailer socket (112), green terminal.
Brown Terminal - Tail Light

When the headlight and trailer light switches are closed, power flows from (B2) battery stud through circuit
14W, 14B, fuse F8-A, and circuit 50 to headlight switch (465). It then flows out of the switch through circuit
58E, cab and trailer lights switch (466), and circuit 58P to energize tail light relay (464)/R9. When relay
energizes, power flows from (B2) battery stud through circuits 14W, 14B, fuse F3-C, and circuit 68 to tail light

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relay. Power then flows through relay normally open contacts, circuit 68E, circuit 68B, conn. (922), conn.
(925), and circuit 68A to the brown terminal of trailer socket (112).

NOTE – The cab trailer lights switch is a momentarily open interrupt switch.

Depressing the switch will interrupt the power to the trailer socket brown terminal.

Black Terminal - Marker Light

When the headlight and trailer light switches are closed, power flows from (B2) battery stud through circuits
14W, 14B, fuse F3–D, and circuit 50 to headlight switch (465). It then flows out of the switch through circuit
58E, cab and trailer lights switch (466), and circuit 58C to energize trailer marker lights relay (463-R8). When
the relay energizes, power flows from (B2) battery stud through circuits 14W, 14E, fuse F3-A, circuit 58D, relay
(463-R8), circuits 58R, 58S , conn. (923), conn. (926) and circuit 58A to the trailer socket black terminal.

Blue Terminal - Trailer ABS

With ignition key on power flows from (B1) through circuit 14CP, fuse F10–A, circuit 94AH, ABS trailer relay
(470), circuit 94AF to the trailer socket (112) blue terminal.

White Terminal - Trailer Socket Ground

The white terminal of (112) is grounded through circuit 11–GAL to sleeper ground, and circuits 11–GN and
11–GI to ground stud at left dash panel.

With Pro Sleeper, the white terminal of (112) is grounded through circuit 11–GAL to trailer socket ground inside
sleeper, circuit 11–GN to the sleeper ground, through circuit 11–GAN to the trailer socket ground inside the
cab, and circuits 11–GN and 11–GI to ground stud at left dash panel.

2.4. TRAILER CONNECTION FOUR WHEEL TRAILER — FRAME MOUNTED

Red Terminal — Stop Light

When the tractor brakes are applied, the vehicle stop light switch supplies power through circuit 70A/70D to
energize the stop light relay (464)/R10. With the stop light relay energized, power from the (B1) battery stud,
circuit 14K/14F, fuse F7–D, and circuit 70E is sent through the normally open contacts of stop light relay on
circuit 70C, connector (922), conn. (925), conn. (318), conn. (113) and circuit 70C to trailer socket connector
(112) at the red terminal.

Yellow and Green Terminals — Turn and Hazard Lights

In the LEFT TURN mode (or hazard switch on), power flows from (B1) battery stud through circuits 14K,
14R, fuse F2–D, circuit 55, flasher, circuits 14BK, 55A and 16BK to turn signal switch. From the switch it
flows through circuit 56E to energize relay (464)/R11. With the left turn relay energized, power flows from
(B1) battery stud through circuits 14K, 14L, fuse F7–B, circuit 56H, through normally open contacts of left
turn relay, circuit 56C, conn. (923), conn. (926), conn. (316), conn. (113) and circuit 56C to the trailer socket
(112), yellow terminal.

In the RIGHT TURN mode (or hazard switch on), power flows from (B1) battery stud through circuits 14K,
14R, fuse F2–D, circuit 55, flasher, circuits 14BK, 55A and 16BK to turn signal switch. From the switch it
flows through circuit 57E to energize relay (464)/R12. With the right turn relay energized, power flows from
(B1) battery stud through circuits 14K, 14L, fuse F7–C, circuit 57H, through normally open contacts of right
turn relay, circuit 57C, connector (923), conn. (926), conn. (316), conn. (113) and circuit 57C to the trailer
socket (112), green terminal.

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Brown Terminal — Tail Light

When the headlight and trailer light switches are closed, power flows from (B2) battery stud through circuits
14H, 14D, fuse F8–A and circuit 50 to headlight switch (465). It then flows out of the switch through circuit
58E, cab and trailer lights switch (466) and circuit 58P to energize tail light relay (464)/R9. When the relay
energizes, power flows from (B2) battery stud through circuit 14W, 14B, fuse F3–C and circuit 68 to tail light
relay. Power then flows through relay normally open contacts, circuit 68E, circuit 68B, connector (922), conn.
(925), conn. (316), conn. (113) and circuit 68B to the brown terminal of trailer socket (112).

NOTE – The cab trailer lights switch is a momentarily open interrupter switch.

Depressing the switch will interrupt the power to the trailer socket brown terminal.

Black Terminal — Marker Light

When the headlight and trailer light switches are closed, power flows from (B2) battery stud through circuits
14W, 14B, fuse F3–D and circuit 50 to headlight switch (465). It then flows out of the switch through circuit
58E, cab and trailer marker lights switch (466), and circuit 58C to energize trailer maker lights relay (463–R8).
When the relay energizes, power flows from (B2) battery stud through circuits 14W, 14E, fuse F3–A, circuit
58D, relay (463–R8), circuits 58S, connector (923), conn. (926), conn. (316), conn. (113) and circuit 58R to
the trailer socket black terminal.

Blue Terminal — Trailer Auxiliary Power

With ignition key on, power flows from (B1) through circuit 14CP, fuse F10–A, circuit 94AH, ABS trailer relay
(470), circuit 94AF, connector (922), conn. (925), conn. (318), conn. (113) and circuit 94AF to the trailer
socket (112) blue terminal.

White Terminal —Trailer Socket Ground

With frame mounted connector for four wheel trailer, the white terminal of (112) is grounded through circuit
11–GN to junction block ground.

Two Speed Axle Wiring

With ignition key on, power flows from (B1) battery stud through circuits 14K, 14R, fuse F2–C, circuit 14S,
ignition relay (462)/R1, and circuit 13P to ignition adapter 12 (495). Then power flows through circuit 93, two
speed axle switch (417), circuits 93A and 93B to the speedometer/tachometer module connector (421). When
the axle is shifted into high range, air is supplied to the axle shift circuit opening the two speed axle switch
and changing the voltage signal to 0 at the speedometer/tachometer module. Thus speed and mileage
are calculated for the different axle ratio.

3. TROUBLESHOOTING
A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 —
ELECTRICAL in the CTS-5000 Master Service Manual.

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D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit, by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the position are generally not covered
in detail. It is assumed that the mechanic knows to check for a malfunctioning switch, relay, or
solenoid.

3.1. AIR DRYER

NOTE – The thermal switch located in the air dryer should only close when the temperature is less than
50°F/10°C, causing the air dryer heater to operate.

Table 130 Air Dryer

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Check 15A fuse F10-A for F10-A. <1 ohm Go to next Locate cause of
open condition. step. overload condition,
then correct.
Replace fuse.
2. Off Remove air dryer relay at (146), 39A 12±1.5 Go to next Locate cause of
connector (146). At (146) to gnd. volts step. low or no voltage
and circuit 39A measure in circuit 39A/14AD,
voltage to ground. then repair.
3. On With key on, at (146) and (146), 12±1.5 Go to next Locate cause of
circuit 13AH measure 13AH to volts step. low or no voltage in
voltage to ground. gnd. circuit 13AH, then
repair.
4. On At (146) measure voltage (146), 12±1.5 Go to next Locate open or poor
between circuits 13AH 13AH to volts step. connection in circuit
and 13-GAD. 13- GAD. 13-GAD, then repair.
5. Off At (146) measure (146), 39B >100K Go to next Locate short to
resistance from circuit to gnd. ohms. step. ground, then repair.
39B to gnd.
6. Off Disconnect connector 36B <5 ohms Go to next Locate open or poor
(1) from air dryer between step. connection in circuit,
pigtail/circuit. Measure (1) and then repair.
resistance of circuit 36B (146).
between connectors (1)
and (146).
7. Off/ On Install air dryer relay 39B to gnd. 12±1.5 Go to next Replace defective air
at (146), and turn key volts step. dryer relay.
on. Measure voltage at
(1)/circuit 39B to gnd.

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Table 130 Air Dryer (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
8. Off Disconnect gnd. circuit 39-G/14BN <5 ohms Go to next Locate open or poor
39-G (14BN with B.W. to gnd. step. connection in circuit,
AD-9) from air dryer. then repair.
Measure resistance
between gnd. and this
circuit.
9. On Turn key on and measure 39-G 14BN 12 ± 1.5 Air dryer Service thermal
voltage between gnd. to air dryer. volts. circuits switch/heater
terminal of air dryer and check assembly of air dryer.
circuit 39-G (or 14BN). good.

3.2. TRUCK BODY CONNECTION

Testing Marker Lights Power Feed

Table 131 Testing Marker Lights Power Feed

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off/ Remove trailer marker (463) /R8, 12±1.5 Go to Locate cause
On lights relay from 58C to gnd. volts next step. of no or low
connector (463-R8). voltage in circuit
Turn key on and place 58C or cab light
headlight switch and cab circuitry, then repair.
and trailer lights switch Refer to Trailer
in on position. Measure Connectionfor
voltage at circuit 58C to feed circuit
ground. troubleshooting.
2. On At (463-R8) measure (463)/R8, 12±1.5 Go to Locate open or poor
voltage from circuit 58C 58C to volts next step. connection in circuit
to 58-GA. 58-GA. 58-GA or 11-G, then
repair.
3. Off Remove fuse F3-A and F3-A. <1 ohm Go to Locate cause of
check for open condition. next step. overload condition,
then correct.
Replace fuse.
4. Off Re-install fuse F3-A and F3-A. 14E 12±1.5 Go to Locate cause of
at the fuse and circuit to gnd. volts next step. low or no voltage,
14E measure voltage to in circuits 14H and
ground. 14E, then repair.
5. Off With trailer marker lights (463)/R8, 12±1.5 Go to Locate cause of
relay still removed, 58D to volts next step. low or no voltage
measure voltage from 58-GA. in circuit 58D, then
circuit 58D to 58-GA. repair.

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Table 131 Testing Marker Lights Power Feed (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
6. Off Disconnect halves of Go to
connector (43), then with next step.
a test lead jumper circuit
58D to circuit 58R.
7. Off Measure voltage to (43), 58R 12±1.5 Go to Locate cause of
ground at connector (43), to gnd. volts next step. low or no voltage
circuit 58R. in circuit 58R, then
repair.
8. Off Remove jumper and Go to
re-install trailer marker next step.
light relay. Then move
headlight and cab and
trailer lights switch to on
position.
9. Off At connector (43) circuit (43), 58S 12±1.5 Go to Replace faulty trailer
58S, measure voltage to to gnd. volts next step. marker lights relay.
ground.
10. Off Turn headlight switch off, Truck body 12±1.5 Marker Locate cause of
reconnect (43) and turn junction volts light low or no voltage
headlight switch back block, 2 to circuit in circuit 58S, then
on. Measure voltage to gnd. checks repair.
ground at terminal 2 of good.
truck body junction block.

Testing Ground Circuit

Table 132 Testing Ground Circuit

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Measure resistance from Gnd stud <2 ohms Junction Locate open or poor
left dash ground stud to to truck block gnd. connection in circuits
terminal 1 of truck body body circuit 11-GM, 11-GN, and
junction block. junction checks 11-GI, then repair.
block 1. good.

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3.3. TRAILER CONNECTION

Testing Stop Light Circuit

Table 133 Testing Stop Light Circuit

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Remove and check fuse F7-D. <1 ohm Go to Locate cause of
F7-D for open condition. next overload condition,
step. then correct. Replace
fuse.
2. Off Re-install fuse F7-D. F7-D, 14F 12±1.5 Go to Locate cause of low or
At fuse F7-D, circuit 14F, to gnd. volts next no voltage in circuits
measure voltage to ground. step. 14F and 14K, then
repair.
3. Off Remove stop light relay (464) /R10, 12±1.5 Go to Locate cause of low
from connector (464)/R10. 70E to gnd. volts next or no voltage in circuit
At (464)/R10 measure step. 70E, then repair.
voltage at circuit 70E to
ground.
4. Off At (464)/R10 measure (464) /R10, 12±1.5 Go to Locate open or poor
voltage from circuit 70E to 70E to volts next connection in circuit
70-G. 70-G. step. 70-G if left turn
indicator functions,
or circuit 56-G if
turn indicator does
not function. Check
57-G/11-G if right turn
indicator does not
function. Then repair
faulty gnd. circuit.
5. Off Remove and check fuse F3-B. <1 ohm Go to Locate cause of
F3-B for open condition. next overload condition,
step. then correct. Replace
fuse.
6. Off Re-install fuse F3-B. F3-B, 14E 12±1.5 Go to Locate cause of low or
At fuse F3-B, circuit 14E to gnd. volts next no voltage in circuits
measure voltage to ground. step. 14H and 14E, then
repair.
7. Off Disconnect stop light (640), 70 12±1.5 Go to Locate cause of low or
switch connector (640). to gnd. volts next no voltage in circuit 70,
At (640) and circuit 70 step. then repair.
measure voltage to gnd.
8. Off With brake pedal Stop light <1 ohm Go to Replace stop light
depressed, measure switch, next switch.
resistance across terminals across step.
of stop light switch. terminals.

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Table 133 Testing Stop Light Circuit (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
9. Off Reconnect (640) and (4), 70A to 12±1.5 Go to Locate cause of low
disconnect (4). With brake gnd. volts next or no voltage in circuit
pedal depressed, at (4) step. 70A, then repair.
measure voltage from
circuit 70A to ground.
10. Off Reconnect (4). With (464)/R10, 12±1.5 Go to Locate cause of low
brake pedal depressed, at 70D to gnd. volts next or no voltage in circuit
(464)/R10 measure voltage step. 70D, then repair.
from circuit 70D to ground.
11. Off At (464)/R10 use test lead Go to
to jumper circuit 70E to next
70C. step.
12. Off With test jumper still in (112), 70C 12±1.5 Go to Locate cause of low
place, measure voltage to gnd. volts next or no voltage in circuit
at trailer socket (112) red step. 70C, then repair.
terminal/circuit 70C to gnd.
13. Off Replace defective stop light
relay. Stop light circuits
check good.

Testing Turn and Hazard Circuits

Table 134 Testing Turn and Hazard Circuits

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Proceed with this test only if Go to next
tractor turn signals, hazard step.
flashers and indicators
work properly. Do turn,
hazard, and indicator lights
of tractor function properly?
2. Off Remove turn signal flasher, Go to next
and use test lead to jumper step.
between circuits 55 and
55A.
3. Off With left turn signal switch (112), 12±1.5 Go to next Locate cause of
on, measure voltage at 56C or volts step. low or no voltage in
trailer socket (112) yellow 56D to circuit 56C or 56D,
terminal/ circuit 56C or 56D gnd. then repair.
to gnd.

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Table 134 Testing Turn and Hazard Circuits (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
4. Off With right turn signal switch (112), 12±1.5 Go to next Locate cause of
on, measure voltage at 57C or volts step. low or no voltage in
trailer socket (112) green 57D to circuit 57C or 57D ,
terminal/circuit 57C or to gnd. then repair.
57D to gnd.
5. Off Test complete; remove
test jumper at flasher and
re-install flasher unit.

Testing Tail Light Circuit

Table 135 Testing Tail Light Circuit

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Proceed with this test only Go to next
if tractor tail lights work step.
properly. Do tail lights of
tractor function properly?
2. Off With head light switch on or (112), 12±1.5 Go to next Locate cause of low
in parking light mode, and 68A or volts. step. or no voltage in circuit
cab and trailer lights switch 68B to 68A or 68B, then
on, measure voltage at gnd. repair.
trailer socket (112) brown
terminal/circuit 68A or 68B
to gnd.
3. Off Tail lights circuit checks
good. Turn off headlight
switch.

Testing Marker Light Circuit

Table 136 Testing Marker Light Circuit

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off Proceed with this test only Go to
if tractor tail lights work next
properly. Do tail lights of step.
tractor function properly?

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Table 136 Testing Marker Light Circuit (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
2. Off Remove marker lights (463)/R8, 58C 12±1.5 Go to Locate cause of low
relay (463-R8). With to gnd. volts next or no voltage in circuit
trailer lights switch on step. 58C, then repair.
and headlight switch
on or in parking light
mode, measure voltage
at (463-R8) circuit 58C to
gnd.
3. Off Remove and check fuse F3-A. <1 ohm Go to Locate cause of
F3-A. next overload condition,
step. then repair.
4. Off Re-install fuse F3-A. F3-A, 14E 12±1.5 Go to Locate cause of low
At fuse holder F3-A, to gnd. volts next or no voltage in circuit
measure voltage from step. 14E, then repair.
circuit 14E to gnd.
5. Off At (463-R8) measure (463)/R8, 58D 12±1.5 Go to Locate cause of low
voltage from circuit 58D to gnd. volts next or no voltage in circuit
to gnd. step. 58D, then repair.
6. Off At (463-R8) measure (463)/R8, 58D 12±1.5 Go to Locate open or poor
voltage from circuit 58D to 58-GA. volts next connection in circuits
to 58-GA. step. 58-GA and 11-G, then
repair.
7. Off At (463-R8) use test lead Go to
to jumper circuit 58D to next
58R. step.
8. Off Measure voltage at (112), 58A or 12±1.5 Go to Locate cause of low
trailer socket (112) black 58R to gnd. volts next or no voltage in circuit
terminal/circuit 58A or step. 58A or 58R, then
58R to gnd. repair.
9. Off Replace defective trailer
marker lights relay.
Marker light circuits check
good.

Testing ABS Trailer Circuit

Table 137 Testing ABS Trailer Circuit

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. On Measure voltage between Blue 12 ± 1.5 ABS trailer Go to next step.
blue terminal circuit 94AF terminal volts. circuits
of trailer socket and circuit check
ground. 94AF of good.
trailer

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Table 137 Testing ABS Trailer Circuit (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
socket &
gnd.
2. Off Remove and check fuse F10-A <1 ohm. Go to next Locate cause of
F10-A for open condition. step. overload condition
and correct. Replace
fuse.
3. Off/ Replace fuse F10-A. (470), 12 ± 1.5 Go to next Locate cause of low
On Remove ABS trailer 94AH and volts. step. or no voltage in circuit
relay (470). Turn key gnd. 94AH or 14CP, then
on and measure voltage repair.
between circuit 94AH and
ground.
4. On Measure the voltage (470), 12 ± 1.5 Go to next Locate open in circuit
between circuits 13-GCP between volts. step. 13-GCP or 13CP, then
and 13CP at connector 13-GCP repair.
(470). and
13CP.
5. Off Remove fuse F-10A and Between 12 ± 1.5 Go to next Locate open in circuit
install a jumper between blue volts. step. 94AF between (470)
circuits 94AH and 94AF terminal, and the trailer socket,
at (470). Install F-10A circuit then repair.
and measure the voltage 94AF,
between blue terminal, of trailer
circuit 94AF, of trailer socket
socket and ground. and gnd.
6. Off Remove jumper and Between 12 ± 1.5 Trailer Replace defective relay
reinstall relay (470). blue volts. ABS (470).
Measure the voltage terminal, circuits
between blue terminal, circuit check
circuit 94AF, of trailer 94AF, good.
socket and gnd. of trailer
socket.

Testing Trailer Socket Ground Circuit

Table 138 Testing Trailer Socket Ground Circuit

STEP KEY ACTION TEST POINTS SPEC. YES-IN NO-OUT OF
SPEC. SPEC.
1. Off With long test leads, (112), white <1 ohm Gnd. Locate open or
measure resistance terminal to circuit poor connection
between left dash panel gnd. stud. checks in ground circuit,
ground stud and white good. then repair.
terminal of trailer socket NOTE: Refer to
(112). circuit diagram
book for ground
circuits which

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Table 138 Testing Trailer Socket Ground Circuit (cont.)

STEP KEY ACTION TEST POINTS SPEC. YES-IN NO-OUT OF
SPEC. SPEC.
vary for different
sleeper models.

3.4. TWO SPEED AXLE WIRING

Table 139 Two Speed Axle Wiring
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. On Turn ignition key on. Go to Go to next step.
Do the speedo/tacho. Step 9.
needles move?
2. Off Remove and check fuse F5-C. <1 ohm Go to Locate cause of
F5-C. next overload condition,
step. then repair. Replace
fuse.
3. Off At fuse holder F5-C F5-C, 12±1.5 Go to Locate cause of low
measure voltage from 14AM to volts next or no voltage in circuit
circuit 14AM to ground. gnd. step. 14AM, then repair.
4. Off Replace fuse F5-C. At (421), 14G 12±1.5 Go to Locate cause of low
(421) measure voltage to gnd. volts next or no voltage in circuit
from circuit 14G to step. 14J or 14G, then
ground. repair.
5. Off Remove and check fuse F4-A. <1 ohm. Go to Locate cause of
F4-A. next overload condition,
step. then repair. Replace
fuse.
6. Off At fuse holder F4-A F4-A, 13B 12±1.5 Go to Locate cause of low
measure voltage from to gnd. volts next or no voltage in circuit
circuit 13B to ground. step. 13B, then repair.
7. Off Replace fuse F4-A. At (421), 28B 12±1.5 Go to Locate cause of low
(421) measure voltage to gnd. volts next or no voltage in circuit
from circuit 28B to gnd. step. 13V or 28B, then
repair.
8. Off At (421) measure voltage (421), 14G 12±1.5 Go to Locate open or poor
from circuit 14G to 11-GL. to 11-GL. volts next connection in ground
step. circuit 11-GL, 11-GQ
or 11-GF , then repair.
9. On With ignition key on (495) to 12±1.5 Go to Go to Power
measure voltage from gnd. volts next Distribution and
ignition adapter (495) to step. Ground System
ground. Troubleshooting
section.

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Table 139 Two Speed Axle Wiring (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
10. Off/ Disconnect two speed (417), 93 12±1.5 Go to Locate cause of low
On axle switch from to gnd. volts next or no voltage in circuit
connector (417). Turn step. 93, then repair.
ignition key on and at
(417) measure voltage
from circuit 93 to ground.
11. Off With two speed axle Axle <1 ohm Go to Replace faulty switch.
switch in the closed switch, next
position (air released) across step.
measure between terminals.
terminals.
12. Off With two speed axle Axle >100K Go to Replace faulty switch.
switch in the open position switch, ohms next
(air applied) measure across step.
between terminals. terminals.
13. Off/ Reconnect two speed (421), 93B 12±1.5 Go to Locate cause of low
On axle switch to connector to gnd. volts. next or no voltage in circuit
(417). disconnect step. 93B, then repair.
connector (421). NOTE:
This will not cause the
digital odometer and
hour meters to lose
their readings. Turn
ignition key on and at
(421) circuit 93B, with
air released to axle
switch, measure voltage
to ground.
14. On At (421) circuit 93B, with (421), 93B 0 volts Go to Locate short to voltage
air applied to axle switch, to gnd. next source in circuit 93B,
measure voltage to gnd. step. then repair.
15. Off Two speed axle wiring
circuits check good.
Refer to GROUP 08 -
ELECTRICAL Gauges
and Warning Lights
section in the CTS-5000
Master Service Manual
for replacement and
programming of the
Speedo/Tachometer
Module.

4. COMPONENT LOCATIONS
J7 Junction Point. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . .. . . . . . In Dash Panel Left Side

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(1) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Left Side of Engine Cowl

(6) Cab/Sleeper Connector.. . .. .. .. . .. .. . .. .. .. . .. .. .. . . . . . Left Back of Cab, “B” Pillar
(43) Truck Body/Trailer Feed. .. .. . .. .. .. . .. .. .. . .. .. .. . . . . . Left Back of Cab, "B" Pillar
(112) Trailer Socket W/O Sleeper. . . . . . . . . . . . . . . . . . .. . . . . . Located on Rear of Cab
(113) Four Wheel Trailer Junction Block. . . . . . . . . . . .. . . . . . Rear Crossmember
(146) Air Dryer Relay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(316) Four Wheel Trailer (Inline).. . .. . . .. . .. . . .. . .. . .. . . . . . Rear of Cab, Inside
(363) AD-9 Air Dryer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Air Dryer
(417) Two Speed Axle Switch.. . .. . .. . .. . .. . .. . .. . .. .. . . . . . Behind Instrument Cluster
(421) Speedo./Tach. Gauge Cluster. . . . . . . . . . . . . . . .. . . . . . At Speedo./Tach. Gauge
(455) G3 Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(494) I1 Ignition Adapter. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . . . Behind Fuse Panel
(497) B1 Battery Adapter. . . . . . . . . . . .. . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel
(499) A1 Accessory Adapter. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel Right Side
(503) L1 Panel Light Feed Adapter.. . .. . .. . .. . .. . .. .. . . . . . Behind Lt Instrument Panel
(506) L4 Panel Light Grd Adapter. . . . . . . . . . . . . . . . . . .. . . . . . At Right of Instrument Panel
(642) Sleeper to Roof Connector with PRO
SLEEPER. .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . . At Lower Left Front Corner of Sleeper Box )
(643) Sleeper to Roof Connector with PRO
SLEEPER. .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . . At Lower Left Front Corner of Sleeper Box)
(922) Trailer Socket #1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Back of Cab, “B” Pillar
(923) Trailer Socket #2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Back of Cab, “B” Pillar
(925) Trailer Socket #1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Back of Cab, “B” Pillar
(926) Trailer Socket #2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Back of Cab, “B” Pillar
(935) Work Light, Trailer. . . .. . . . . .. . . . .. . . . .. . . . .. . . . .. . . . . . Left Back of Cab, “B” Pillar

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Figure 129 Air Dryer Wiring

1. (1) DASH PANEL CONNECTOR
2. CIRCUIT 39B
3. CIRCUIT 39A
4. FUSE F10-A, 15A
5. B2 BATTERY STUD
6. B1 BATTERY STUD
7. AIR DRYER RELAY (146)

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Figure 130 Air Dryer Wiring

1. CIRCUITS 14RD & 14BN
2. FRONT END HARNESS TO DASH PANEL CONNECTOR (1)
3. CIRCUIT 39
4. CIRCUIT 39-G
5. CONNECTOR (363)
6. CIRCUIT 14RD & 14BN
7. BENDIX AD-9 AIR DRYER

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Figure 131 Trailer Connection N/Sleeper

1. MAIN CAB HARNESS
2. CONNECTOR (922) & (923)
3. TRAILER SOCKET (112)
4. CIRCUIT 11-GN
5. CIRCUIT 11-GAN
6. TRAILER SOCKET GROUND
7. CIRCUIT 11-GN

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Figure 132 Pro Sleeper Wiring

1. ROOF HARNESS CONNECTOR (643)
2. ROOF HARNESS CONNECTOR (642)
3. SLEEPER CONNECTOR # 1 (906)
4. TRAILER SOCKET CONNECTOR (922)
5. TRAILER SOCKET CONNECTOR (923)
6. WORK LIGHT CONNECTOR #2 (935)
7. SLEEPER CONNECTOR #2 (942)
8. SLEEPER GROUND
9. TRAILER SOCKET CONNECTORS (925) AND (926)
10. TRAILER SOCKET (112)

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Figure 133 Trailer Connection With Trailer Cable Wired Directly to Cab Harness

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1. TRAILER SOCKET GROUND

2. CONNECTOR (5)
3. CIRCUITS 58S AND 68B TO BLACK AND BROWN WIRE
4. CIRCUITS 70 AND 72 TO RED AND BLUE WIRE
5. CIRCUITS 56C AND 57C TO YELLOW AND GREEN WIRE
6. 11–GT AND WHITE WIRE
7. 7–WAY COILED TRAILER CABLE

Figure 134 Trailer Connection With Four Wheel Trailer N/Sleeper Box
1. TRAILER SOCKET WIRING
2. TRAILER IN-LINE CONNECTOR (316)
3. TRAILER IN-LINE CONNECTOR (318)
4. HARNESS ASSEMBLY
5. CONNECTORS (922) & (923)
6. MAIN CAB HARNESS

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Figure 135 Trailer Connection With Four Wheel Trailer

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1. 7-WAY SOCKET HARNESS

2. TRAILER SOCKET WIRING
3. 7-STUD JUNCTION BLOCK BOX (113)
4. 7-WAY SOCKET (112)
5. 7-STUD JUNCTION BLOCK BOX (113)
6. TRAILER SOCKET WIRING

Figure 136 Two Speed Axle Wiring

1. TWO SPEED AXLE SWITCH (417)
2. SPEEDOMETER/TACHOMETER (421)
3. 2 SPEED AXLE WIRING HARNESS CIRCUIT 93
4. I2 IGNITION ADAPTER (495)
5. CAB MAIN HARNESS

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Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .435
1.1. BACK-UP LIGHTS. .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .435
1.2. CAB AND TRAILER LIGHTS SWITCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .435
1.3. CAB CLEARANCE AND IDENTIFICATION LIGHTS. .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .435
1.4. CAB DOME, READING, AND COURTESY LIGHTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .435
1.5. DAYTIME RUNNING LIGHTS (DRL) MODULE WIRING-STANDARD USA AND CANADA. . .435
1.6. FOG LIGHTS.. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .435
1.7. HEADLIGHT SWITCH AND DIMMER SWITCH WIRING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .435
1.8. HEADLIGHTS .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .435
1.9. PANEL LIGHTS. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .436
1.10. PARK/TURN/MARKER LIGHTS.. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .436
1.11. SPOTLIGHT. .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .436
1.12. STOP, TAIL, TURN AND HAZARD SIGNAL LIGHTS WITH FLASHER. . . . . . . . . . . . . . . . . . . . . . . . .436
1.13. WORK LIGHT WITHOUT SLEEPER.. .. . .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .436
1.14. WORK LIGHT WITH PRO SLEEPER. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .436

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .436
2.1. BACK-UP LIGHTS. .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .436
2.2. CAB AND TRAILER LIGHTS SWITCH AND RELAYS WIRING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .436
2.3. CAB CLEARANCE AND IDENTIFICATION LIGHTS. .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .437
2.4. CAB DOME, READING, AND COURTESY LIGHTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .437
2.5. DAYTIME RUNNING LIGHTS (DRL) MODULE WIRING-STANDARD USA AND CANADA. . .437
2.6. FOG LIGHTS.. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .438
2.7. HEADLIGHT SWITCH AND DIMMER SWITCH WIRING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .438
2.8. HEADLIGHTS .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .438
2.9. PANEL LIGHTS. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .439
2.10. PARK/TURN/MARKER LIGHTS . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .439
2.11. SPOTLIGHT. .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .440
2.12. STOP, TAIL, TURN AND HAZARD SIGNAL LIGHTS WITH FLASHER. . . . . . . . . . . . . . . . . . . . . . . . .440
2.13. WORK LIGHT WITHOUT SLEEPER.. .. . .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .440
2.14. WORK LIGHT WITH PRO SLEEPER. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .441

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .441
3.1. BACK-UP LIGHTS. .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . .. .441
3.2. CAB AND TRAILER LIGHTS SWITCH AND RELAYS WIRING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .442
3.3. CAB CLEARANCE AND IDENTIFICATION LIGHTS. .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .445
3.4. CAB DOME, READING, AND COURTESY LIGHTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .447
3.5. DAYTIME RUNNING LIGHTS (DRL) MODULE WIRING- STANDARD USA AND CANADA.. .453
3.6. FOG LIGHTS.. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .456
3.7. HEADLIGHT SWITCH AND DIMMER SWITCH WIRING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .458
3.8. HEADLIGHTS. .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .462
3.9. PANEL LIGHTS. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .464
3.10. PARK/TURN/MARKER LIGHTS . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .467
3.11. SPOTLIGHT. .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .470
3.12. STOP, TAIL, TURN AND HAZARD SIGNAL LIGHTS WITH FLASHER. . . . . . . . . . . . . . . . . . . . . . . . .471
3.13. WORK LIGHT WITHOUT SLEEPER.. .. . .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .477
3.14. WORK LIGHT WITH PRO SLEEPER. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .479

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4. COMPONENT LOCATIONS. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . ..481

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1. DESCRIPTION
1.1. BACK-UP LIGHTS
The vehicle back-up lights are a set of lamps that come on when the vehicle transmission is shifted into reverse.

1.2. CAB AND TRAILER LIGHTS SWITCH

The cab and trailer lights switch is a switch that is used to flash (momentarily turn off) the tractor and trailer
clearance and tail lights. Thus the truck operator can thank the driver of the vehicle he has just passed for
flashing his headlights, signaling that it is safe to merge back into the driving lane.

1.3. CAB CLEARANCE AND IDENTIFICATION LIGHTS

Cab identification lights function to provide quick visual identification of trucks and tractors in the dark. They
are required on trucks and tractors wider than 80 inches to distinguish them from automobiles. Clearance
lights are located at the widest points of the cab roof to identify the width of the vehicle.

1.4. CAB DOME, READING, AND COURTESY LIGHTS

The left and right dome lights provide light when they are switched on at the dome light switch, or when the cab
doors are opened and the dome light switch is set for automatic operation. Thus the driver is able to fill out
log books, etc., and enter and exit the cab safely after dark. The left and right reading lights are controlled
individually by a switch at each lamp. They are used individually or in addition to the dome light.

1.5. DAYTIME RUNNING LIGHTS (DRL) MODULE WIRING-STANDARD USA AND

CANADA
This circuit consists of a Daytime Running Lights module, a park brake switch, and park brake indicator, thus
providing a DRL system that runs the headlights at a reduced brightness during the day to allow for greater
vehicle visibility. The reduced brightness provides an extended bulb life.

1.6. FOG LIGHTS

Fog lights are a set of lights that are mounted low on the front of the truck and operate only when the headlights
are on in the low beam mode. (Many state laws prohibit operation of fog lights with the high beam headlights
on.) Since they are mounted low, they are useful in foggy conditions.

NOTE – Fog lights will only function if headlight switch is in the on position, dimmer switch is in low
position, and the fog light switch is in the on position.

1.7. HEADLIGHT SWITCH AND DIMMER SWITCH WIRING

The headlight switch and circuits function to turn on and off the headlights and when on or in parking light
position, allow parking and clearance lights to function if they are selected. The dimmer switch is used to
switch between low beam (dim) elements and high beam (bright) elements.

1.8. HEADLIGHTS
The 5000i, 9100i, 9200i, 9400i, and 9900i model trucks use a two headlamp system. Each lamp contains a low
beam element and a high beam element.

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1.9. PANEL LIGHTS

Panel lights are low wattage bulbs that illuminate gauges and other miscellaneous items. The panel light
switch dims/brightens panel lights for the right and left gauge cluster, speedo/tach module, analog clock, air
restriction gauge, cigar lighter, and heater control.

1.10. PARK/TURN/MARKER LIGHTS

This set of circuits consists of left and right side turn lights, and left and right side combination park, turn,
and marker light units.

1.11. SPOTLIGHT
The spotlight circuit provides power for two spotlights. The switches for these spotlights are built into the lights.

1.12. STOP, TAIL, TURN AND HAZARD SIGNAL LIGHTS WITH FLASHER
This set of circuits contains the turn signal switch, stop light switch, flasher unit (turn signal/hazard), right and
left turn relays, stop light relay, and right and left stop, turn, and tail light assemblies for the rear of the vehicle.
The turn indicators located in the instrument cluster are also included.

1.13. WORK LIGHT WITHOUT SLEEPER

The work light circuit consists of a work light, a work light switch, and an indicator light located in the instrument
cluster. This light is located on the back of the cab and provides light for the operator when the trailer air and
electrical lines are being connected or disconnected from the trailer.

1.14. WORK LIGHT WITH PRO SLEEPER

The work light circuit consists of two work lights, a work light switch, and an indicator light located in the
instrument cluster. These lights are located on the back of the sleeper and provide light for the operator when
the trailer air and electrical lines are being connected or disconnected from the trailer.

2. OPERATION
Refer to the LIGHT SYSTEMS circuit diagrams in CTS-5298 or S08225.

2.1. BACK-UP LIGHTS

When the ignition switch is in the (ignition position), the ignition relay energizes and power is supplied to fuse
F4-C. When the transmission is placed into reverse, the back-up light switch closes and power flows to the
back-up lights. Power flows from fuse F4-C through circuit 71, a white wire, back-up switch (230), a black wire,
circuit 71A, the left and right back-up lights, and ground circuit 11-GV.

2.2. CAB AND TRAILER LIGHTS SWITCH AND RELAYS WIRING

When the headlight switch is in the on or in the parking light position, power flows through circuit 58E and
cab and trailer lights switch (466) unless the cab and trailer lights switch is held open. After flowing through
the switch, power flows out 58C, trailer marker lights relay (463-R8) and 58P to cab and trailer lights relay
(464-R9). The trailer marker lights relay then becomes energized as the power flows through it to the ground
circuits 58-GA and 11-G. This allows power to flow through circuits 14H, 14E, fuse F3-A, circuit 58D, trailer
marker lights relay, and through circuits 58R, and 58S to the trailer socket. Likewise the cab and trailer tail
lights relay becomes energized as the power flows from the cab and trailer lights switch and through the relay

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coil and ground circuit 58-G. This allows power to flow through circuits 14H, 14B, fuse F3-C, circuit 68,
through cab and trailer tail lights relay, and through circuit 68E. From this point it flows through circuit 68B
to the trailer socket. It also flows through circuit 68D, fuse F8-C, and circuit 68C to supply mirror lights, tail
lights, clearance lights, panel lights, and park lights.

2.3. CAB CLEARANCE AND IDENTIFICATION LIGHTS

As described above in Cab and Trailer Lights Switch and Relays Wiring, power is fed to circuit 68E. It then
flows through circuit 68D, fuse F8-C, circuit 68C, and circuit 58A to the cab clearance and identification
lights. After dividing up to flow through the lights, the power flows through ground circuits 11-GAC, 11-GAB,
11-GAC, and 11-GB to right dash ground stud.

2.4. CAB DOME, READING, AND COURTESY LIGHTS

The two reading lamps are powered through circuits 14H, 14Y, fuse F1-D, and circuit 63P. The circuit then
splits up to 63R going to the left reading light pigtail connector (312) and circuit 63T going to the right reading
light pigtail connector (311). The ground circuit for the reading lights is 63-GR (left) or 63-GT (right), 11-GAB
and 11-GB to right dash panel ground stud.

The dome light switch is illuminated by circuits 62A, 62S, 62AP, and 63F coming from the panel light switch.
The ground circuit is 62-GF, 11-GAB and 11-GB to right dash panel ground stud. When the dome light switch is
set to on, power flows from (B2) battery stud through circuits 14AG, 14T, fuse F2-B, and circuit 63. From this
point power flows to left courtesy light through circuit 63V, or right courtesy light through circuits 63X and 63V,
or right dome light through circuits 63Z, 63, and 63S, or left dome light through circuits 63Z, 63, and 63M.

The ground path for the left courtesy light is circuits 63H, 63A, dome light switch, circuits 63-GD, 11-GAB, and
11-GB to right dash ground stud. The ground path for the right courtesy light is circuits 63H, 63Y, 63A, dome
light switch, circuits 63-GD, 11-GAB, and 11-GB to right dash ground stud.

The ground path for the right dome light is circuits 63Y, 63A, dome light switch, circuits 63-GD, 11-GAB, and
11-GB to right dash ground stud. The ground path for the left dome light is circuit 63N, dome light switch,
circuits 63-GD, 11-GAB, and 11-GB to right dash ground stud. If the dome light switch is set to automatic
operation, the ground path for all the courtesy and dome lights becomes circuit 63B, and circuit 63C to ground
when a door is opened.

2.5. DAYTIME RUNNING LIGHTS (DRL) MODULE WIRING-STANDARD USA AND

CANADA
The daytime running light system uses an electronic module to control the lights. Power flows from the (B1)
battery adapter (497) through circuit 14BL, fuse F10-B, and circuit 66A to the DRL module (513). The ground
circuit is made up of 66-GA and 66-G to ground adapter (453). When the ignition key is turned to accessories
or on (ignition) position, power flows from I2 ignition adapter (495) through circuit 13BL, fuse F10-A, and circuit
66D to the DRL module (513). When the park brake is applied, the park brake switch (468) is closed and
power flows through fuse F4-A, circuits 13V, 28C, park brake lamp (420), circuit 44, 44A, 44B, DRL park brake
switch, circuit 44-GB, and 66-G to ground adapter (453).

When the park brake is released, the DRL park brake switch opens and the voltage that the DRL module
senses at connector (513) terminal E goes to 12 ± 1.5V. This tells the module to power the low beam elements
of the headlights at 50% of normal low beam brightness, which is 75% to 84% of battery voltage. When the
headlight switch is turned on, the brightness will go to 100%.

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2.6. FOG LIGHTS

Fog lights operate only when the headlights are on in the low beam mode. (Many state laws prohibit operation
of fog lights with the high beam headlights on.)

The fog light switch (440) is used to enable the fog light system by energizing the fog light relay (148). The
switch receives power from the dimmer switch (only in low beam position) or Daytime Running Lights module,
on circuit 64C. Closing the switch applies power through circuit 64A to the control coil of the fog light relay,
which energizes the relay.

Accessory power from A3 flows through circuit 12P, fuse F10-A, and circuit 64 to fog light relay (148). With the
fog light relay energized, power flows through the relay, and circuit 64B to circuits 64C and 64D delivering
power to the fog lights.

2.7. HEADLIGHT SWITCH AND DIMMER SWITCH WIRING

The headlight switch and dimmer switch wiring circuits along with the headlight relay, all covered in this
section, regulate power to the headlights, tail lights, marker lights, fog lights and daytime running light
circuits. When the headlight switch is placed in accessory or on (ignition) position, power is available from
(B2) battery stud, through circuits 14H, 14D, fuse F8-A, circuit 50, headlights switch (465), and circuit 58E to
the cab and trailer lights switch.

If the headlight switch is placed in on (ignition) position, power is available from (B2) battery stud, through
circuit 14H, 14B, fuse F3-D, and circuit 50A to the headlights switch (465). If the headlight switch is on,
current will flow through the switch and circuit 50B to energize the headlight relay (462-R4). Circuits 50-GB
and 11-G complete the ground circuit.

With the headlight relay energized, current flows from (B2) battery stud, through circuits 14H, 14D, fuse F8-B,
circuit 51, headlight relay (462-R4), and circuit 51A, to dimmer switch (42). With the dimmer switch in the
low position, current will flow through circuit 53B to a splice. From the splice power will flow through circuit
53D to the left headlight and 53C to the right headlight. Then the current will flow through circuits 52–GE,
52–GF, and 11–GF to ground stud at left dash panel. With the dimmer switch in the high position, current will
flow through circuit 52F to a splice. From the splice power will flow through circuit 52D to the left headlight
and 52E to the right headlight. Then the current will flow through circuits 52–GE, 52–GF, and 11– GF to
ground stud at left dash panel.

With the standard USA and Canadian DRL system, with the headlight switch off, power flows from the DRL
module through circuits 66B, 64C, and 53B to a splice. From the splice power will flow through circuit 53D to
the left headlight and 53C to the right headlight. Then the current will flow through circuits 52–GE, 52–GF, and
11–GF to the ground stud at the left dash panel.

2.8. HEADLIGHTS
These models utilize a two headlight system, one on each side. The lamps receive power in the low beam
mode on circuit 53B with the power split up on 53C for the right lamp and 53D for the left lamp. The lamps
receive power in the high beam mode from circuit 52F, with power split up on 52E for the right lamp and 52D
for the left lamp.

Circuits 52–GE, 52–GF, and 11–GF provide the ground path for the left headlight to left dash panel ground
stud. Circuits 52–GA and 64–GC provide the ground path for the right headlight to J7 cab ground.

Circuits 52–GD, 52–GB, and 52–GA provide the ground path for the left headlights to J7 cab ground. Circuits
52–GH, 52–GF, 52–GE, 52–GF, and 11–GF provide the ground path for the right headlights.

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2.9. PANEL LIGHTS

When the headlight switch is in the park or on position, and the cab and trailer lights switch is on, the cab and
trailer lights relay is energized and power flows on circuits 68E and 68D through fuse F8-C to circuits 68C
and 62. From here current flows through panel light switch (425). The panel light switch is grounded through
circuits 11–GS, 11–GK, and 11–GD to the left dash panel ground stud. The panel light switch (425) contains an
integrated circuit that provides a variable voltage to adjust the brightness of the panel lights.

From the panel light switch power flows through circuits 62A, 62S, 62M, panel lights feed adapter (503), and
circuit 62AQ to the analog clock lamp. The ground path is circuit 62-GAQ and 11-GAV to ground adapter (454).

From the panel light switch power flows through circuits 62A, 62S, 62M, panel lights feed adapter (503), and
circuit 62AB to the air restriction gauge lamp. The ground path is circuit 62-GAB to ground adapter (506).

From the panel light switch power flows through circuits 62A and 62D to the speedo/tach module panel lights
and through circuits 62-GD and 11-GF to ground stud at left dash panel.

From the panel light switch power flows through circuits 62A and 62C to the left gauge cluster panel lights and
through circuits 62-GC and 11-GF to ground stud at left dash panel.

From the panel light switch power flows through circuits 62A and 62B to the right gauge cluster panel lights
and through circuits 62-GB and 11-GF to ground stud at left dash panel.

From the panel light switch power flows through circuits 62A and 62T to the cigar lighter light and directly
to ground.

From the panel light switch power flows through circuits 62A, 62S, and 62P to the heater control (105) light and
through circuits 62-GP and 11-G to ground stud at right dash panel.

From the panel light switch power flows through circuits 62A, 62S, and 62P to the heater control (105) light and
through circuits 62–GP and 11–G to ground stud at right dash panel.

2.10. PARK/TURN/MARKER LIGHTS

When the headlight switch is in the park or on position, and the cab and trailer lights switch is on, the cab and
trailer lights relay is energized and power flows on circuits 68E and 68D through fuse F8-C to circuits 68C and
58H. Then the current is split through circuit 58T to the left park/turn/marker light low element and circuit 58U
to the right park/turn/marker light low element. The ground circuits are 52–GE from the left light and 52–GA
from the right light through 64–GC to J7 cab ground.

The turn signal switch provides power on circuit 56D to the left side turn light element and circuit 56 to the
left/park/turn/marker light high element.

The turn signal switch provides power on circuit 57D to the right side turn light element and circuit 57 to the
right/park/turn/marker light high element.

The ground path for the park/turn/marker lights was mentioned above. The ground path for the left side turn
light is circuit 56-GA and 11-GD to ground stud at left dash panel. The ground path for the right side turn light is
circuit 57-GA, and 11-GB to ground stud at right dash panel.

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2.11. SPOTLIGHT
(B2) battery stud supplies power through circuits 14H, 14Y, fuse F1-D, circuits 63P, and 64E. The power is
available at this point to circuit 64H and the left spotlight and switch assembly, or circuit 64F and the right
spotlight and switch assembly. The lights are grounded through their mounting brackets.

2.12. STOP, TAIL, TURN AND HAZARD SIGNAL LIGHTS WITH FLASHER
When the brakes are applied, stoplight switch (640) closes and power flows from (B2) battery stud through
circuits 14H and 14E to fuse F3-B. From the fuse, power flows through circuit 70, stoplight switch, and circuit
70A, to turn signal switch and circuit 70D to stoplight relay (464)/R10.

This energizes the stoplight relay through ground path circuits 70-G, 56-G, 57-G, and 11-G to ground stud at
right dash panel. This allows power to flow from (B1) battery stud through circuits 14K, and 14F to fuse F7-D.
From the fuse, power flows through circuit 70E, stoplight relay (464)/R10 and circuit 70C to the trailer socket.

From the turn signal switch power flows through circuit 56B to bright element of the left rear stop, tail, and turn
light, and the four wheel trailer connection. Power also flows from the turn signal switch on circuit 57B to bright
element of the right rear stop, tail, and turn light, and the four wheel trailer connection. Circuit 11-GV is the
ground path for the left and right rear stop, tail, and turn light.

When the turn signal switch is moved to the left turn position, power flows from (B1) battery stud through
circuits 14K, 14R, fuse F2-D, and circuit 55 to the flasher unit. From the flasher unit power flows through
circuit 55A, and the turn signal switch.

From the turn signal switch power flows through circuit 56D to the left side turn light, and 56E to the left
turn relay (464)/R11. The left turn relay is energized through ground path circuits 56-G, 57-G, and 11-G to
ground stud at right dash panel. Power also flows from the turn signal switch through circuit 56B to the four
wheel trailer connection and the bright element of the left rear stop, tail, and turn light. Circuit 11-GV is the
ground path for the left rear stop, tail, and turn light.

With the left turn relay energized, power flows from (B1) battery stud through circuits 14K, 14L, fuse F7-B, and
circuit 56H to the left turn relay. Power then flows through circuit 56C to the trailer socket, and circuits 56A and
56R to the left turn indicator. The ground path is circuit 62-GD and 11-GF to ground stud left dash panel.

When the turn signal switch is moved to the right turn position, power flows from the turn signal switch, through
circuit 57D to the right side turn light, and circuit 57E to the right turn relay (464)/R12. The right turn relay is
energized through ground path circuits 57-G, and 11-G to ground stud at right dash panel. Power also flows
from the turn signal switch through circuit 57B to the four wheel trailer connection and the bright element of
the right rear stop, tail, and turn light. Circuits 11-GV and 11–GV make up the ground path for the right
rear stop, tail, and turn light.

With the right turn relay energized power flows from (B1) battery stud through circuits 14K, 14L, fuse F7-C, and
circuit 57H to the right turn relay. Power then flows through circuit 57C to the trailer socket, and circuits 57A
and 57R to the right turn indicator. The ground path is circuits 62-GD and 11-GF to ground stud left dash panel.

2.13. WORK LIGHT WITHOUT SLEEPER

When work light switch is moved to the on position, power flows from the (B2) battery stud through circuit 14T,
fuse F2-A, circuit 65A, work light switch (441), and circuit 65B to the work light. The ground path is circuits
65-GB and 11-GAN to the trailer socket ground. With the work light switch in the on position, power also flows
from fuse F4-A through circuits 13V, 28A, work light indicator light, circuit 65C, work light switch, and circuits
65-GC and 11-GAN to trailer socket ground, thus indicating that the work light switch is turned on.

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2.14. WORK LIGHT WITH PRO SLEEPER

When the work light switch is moved to the on position, power flows from the (B2) battery stud through circuit
14T, fuse F2-A, circuit 65A, work light switch (441), and circuit 65B to the left work light, and 65F to the right
work light. The ground path for the left work light is circuits 65-GB, 11-GBC, 11-GBD and 11-GBE to ground
adapter (454). The ground path for the right work light is circuits 65-GB, 65-GF, 11-GBC, 11-GBD, and 11-GBE
to ground adapter (454). With the work light switch in the on position, power also flows from fuse F4-A through
circuits 13V, 28A, work light indicator light, circuit 65C, work light switch, and circuit 65-GC, 11-GBD, and
11-GBE to the ground adapter (454), thus indicating that the work light switch is turned on.

3. TROUBLESHOOTING
Refer to the LIGHT SYSTEMS circuit diagrams in CTS-5298 or S08225.

A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 —
ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not
covered in detail. It is assumed that the technician knows to check for a malfunctioning switch,
relay, or solenoid.

3.1. BACK-UP LIGHTS

Table 140 Back-Up Lights
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off Check fuse F4-C. F4-C. <1 ohm. Go to Locate cause of
next overload condition,
step. then repair. Replace
fuse.
2. On At F4-C measure voltage F4-C, 13H 12±1.5 Go to Locate cause of low
from 13H to ground. to gnd. volts. next or no voltage in circuit
step. 13H, then repair.
3. Off/ Remove connector (230) (230), white 12±1.5 Go to Locate cause of low
On from back-up light switch. wire to gnd. volts. next or no voltage in circuit
Turn key on and measure step. 71 or white wire, then
voltage from white wire to repair.
ground.

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Table 140 Back-Up Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
4. Off With transmission in Back-up <1 ohm. Go to Replace defective
reverse, measure light sw., next switch, reconnect
resistance across terminals across step. connector (230).
of back-up light switch terminals.
(230).
5. Off/ Disconnect connector (127), 71A 12±1.5 Go to Locate cause of low
On (127), turn key on, and to gnd. volts. next or no voltage in circuit
place transmission in step. 71A, then repair.
reverse. Measure voltage
at connector (127), circuit
71A to gnd.
6. On Measure voltage at (127), 71A 12±1.5 Go to Locate open or poor
connector (127), circuit to 11-GV. volts. next connection in circuit
71A to circuit 11-GV. step. 11-GV, then repair.
7. Off Back-up light circuits
check good. Replace any
defective back-up lights.

3.2. CAB AND TRAILER LIGHTS SWITCH AND RELAYS WIRING

Table 141 Cab and Trailer Lights Switch and Relays Wiring
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
1. Off Disconnect connector (466), 58E to 12 ± 1.5 Go to next Locate cause of
(466) from cab and gnd. volts. step. low or no voltage
trailer lights switch, move in circuit 58E, then
headlight switch to park or repair.
on position, and measure
voltage from circuit 58E
to ground.
2. Off With cab and trailer lights Cab and <1 ohm. Go to next Replace defective
switch in the on position, trailer lights step. switch, reconnect
measure resistance switch, 5 to 6. connector (466).
across terminals 5 and 6.
3. Off Is cab and trailer Across .6 to .8 Go to Step Go to next step.
lights switch indicator switch volt diode 7.
functioning? indicator drop.
4. Off Use diode test function on Go to next Replace defective
Fluke meter to test. Does step. switch, reconnect
indicator check good? connector (466).

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Table 141 Cab and Trailer Lights Switch and Relays Wiring (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
5. Off With headlight switch (466), 62AR 11 ± 1.5 Go to next Locate cause of
on and panel light to gnd. volts. step. low or no voltage in
switch adjusted for full circuit 62A, 62AS,
brightness, at connector or 62AR from panel
(466) measure voltage to light switch, then
ground at circuit 62AR. repair.
6. Off At conn. (466) with (466), 62AR 11 ± 1.5 Go to next Locate open or
headlight switch on to 62- GAR. volts. step. poor connection
and panel light switch in ground circuit
adjusted for full 62-GAR, 11-GK,
brightness, measure or 11-GD going to
voltage from circuit 62AR ground stud at left
to 62-GAR. dash panel, then
repair.
7. Off Reconnect conn. (466), (464-R9), 12 ± 1.5 Go to next Locate cause of
and remove cab and 58P to gnd. volts. step. low or no voltage
trailer tail lights relay in circuit 58P, then
(464-R9). With the cab repair.
and trailer lights switch in
the on position, measure
voltage at relay socket
(464-R9) circuit 58P to
ground.
8. Off Measure voltage at relay (464-R9), 12 ± 1.5 Go to next Locate open or poor
socket (464-R9) circuit 58P to 58-G. volts. step. conn. in circuits
58P to 58-G. 58-G, 70-G, 58-G,
57-G, and 11-G to
ground stud at right
dash panel, then
repair. Re-install
relay.
9. Off Check fuse F3-C. F3-C. <1 ohm. Go to next Locate cause of
step. overload condition,
then repair. Replace
fuse.
10. Off Replace fuse F3-C. At F3-C, 14B to 12 ±1.5 Go to next Locate cause of
F3-C measure voltage gnd. volts. step. low or no voltage in
from circuit 14B to ground. circuit 14H or 14B,
then repair.
11. Off Measure voltage at relay (464-R9), 68 12 ±1.5 Go to next Locate cause of
socket (464-R9) circuit 68 to 58-G. volts. step. low or no voltage
to 58-G. in circuit 68, then
repair. Re-install
relay.

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Table 141 Cab and Trailer Lights Switch and Relays Wiring (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
12. Off At relay socket (464-R9) Go to next
with test lead jumper step.
connect circuit 68 to 68E.
13. Off Remove and check fuse F8-C <1 ohm. Go to next Locate cause of
F8-C. step. overload condition,
then repair. Replace
fuse.
14. Off Re-install fuse F8-C. F8-C, 68D to 12 ±1.5 Go to next Locate cause of
At fuse F8-C measure gnd. volts. step. low or no voltage
voltage from circuit 68D in circuit 68E or
to ground. 68D, then repair.
Re-install relay.
15. Off Remove test jumper, F8-C, to gnd. 12 ±1.5 Go to next Replace cab and
and re-install cab and volts. step. trailer tail lights
trailer tail lights relay. relay.
Turn headlight switch on
and cab and trailer lights
switch on. At fuse F8-C
measure voltage from
circuit 68D to ground.
16. Off With headlight switch Trailer 12 ±1.5 Go to next Locate cause of
and cab and trailer socket, 68B volts. step. low or no voltage
lights switch still on, at to gnd. in circuit 68B, then
trailer socket measure repair.
voltage from circuit 68B
to ground.
17. Off Park, panel, clearance, Go to next
and mirror lights, and step.
trailer tail lights power
feed circuit checks good.
18. Off Remove trailer marker (463-R8), 12 ±1.5 Go to next Locate cause of
lights relay from socket 58C to gnd. volts. step. low or no voltage in
(463-R8). With headlight circuit 58C or jumper
switch and cab and trailer between 58C and
lights switch still on, 58P, then repair.
measure voltage from
circuit 58C to ground.
19. Off With headlight switch (463-R8), 12 ±1.5 Go to next Locate cause of
and cab and trailer lights 58C to volts. step. low or no voltage
switch still on, measure 58-GA. in circuit 58-GA or
voltage from circuit 58C 11-G, then repair.
to 58-GA.

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Table 141 Cab and Trailer Lights Switch and Relays Wiring (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
20. Off Remove and check fuse F3-A. <1 ohm. Go to next Locate cause of
F3-A. step. overload condition,
then repair. Replace
fuse.
21. Off Re-install fuse F3-A. F3-A, 14E to 12 ±1.5 Go to next Locate cause of
At fuse F3-A measure gnd. volts. step. low or no voltage in
voltage from circuit 14E circuits 14H or 14E,
to ground. then repair.
22. Off At (463-R8) measure (463-R8), 12 ±1.5 Go to next Locate cause of
voltage from circuit 58D 58D to gnd. volts. step. low or no voltage
to ground. in circuit 58D, then
repair.
23. Off At (463-R8) use test lead Trailer 12 ±1.5 Go to next Locate cause of
to jumper circuit 58D to socket, 58S volts. step. low or no voltage in
58R. At trailer socket to gnd. circuit 58R or 58S,
measure voltage from then repair.
circuit 58S to gnd.
24. Off Remove test jumper Trailer 12 ±1.5 Trailer Replace defective
and re-install trailer socket, 58S volts. marker trailer marker lights
marker lights relay. With to gnd. lights relay.
headlights and cab and circuits
trailer lights switched on, check
at trailer socket measure good.
voltage from circuit 58S
to gnd.

3.3. CAB CLEARANCE AND IDENTIFICATION LIGHTS

Table 142 Cab Clearance and Identification Lights
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off With headlight switch off, F8-C. <1 ohm. Go to Locate cause of
check fuse F8-C. next overload condition,
step. then repair. Replace
fuse.
2. Off At F8-C measure voltage F8-C, 68D 12 ±1.5 Go to Go to test Cab &
from 68D to gnd. to gnd. volts next Trailer Lights Sw.
step. & Relays Wiring to
locate cause of low
or no voltage at fuse
F8-C, then repair.

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Table 142 Cab Clearance and Identification Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
3. Off Disconnect connector (428), 58A 12 ±1.5 Go to Locate cause of low
(428). With headlight and to gnd. volts. next or no voltage in circuit
cab and clearance lights step. 68C or 58A, then
switches turned on, at repair.
(428) measure voltage at
circuit 58A to ground.
4. Off If clearance lamp at Go to Replace defective
connector (520) does not next bulb.
illuminate, check bulb step.
filament. Bulb OK?
5. Off Disconnect connector (520), 58B 12 ±1.5 Go to Locate cause of low
(520). With headlight, and to gnd. volts. next or no voltage in circuit
cab and clearance lights step. 58B, then repair.
switches turned on, at
(520) measure voltage at
circuit 58B to ground.
6. Off At (520) measure voltage (520), 58B 12 ±1.5 Go to Locate open or poor
at circuit 58B to 58-GB. to 58-GB. volts. next connection in circuit
step. 58-GB, then repair.
7. Off If clearance lamp at Go to Replace defective
connector (521) does not next bulb.
illuminate, check bulb step.
filament. Bulb OK?
8. Off Disconnect connector (521), 58C 12 ±1.5; Go to Locate cause of low
(521). With headlight, and to gnd. volts. next or no voltage in circuit
cab and clearance lights step. 58C, then repair.
switches turned on, at
(521) measure voltage at
circuit 58C to ground.
9. Off At (521) measure voltage (521), 58C 12 ±1.5 Go to Locate open or poor
at circuit 58C to 58-GC. to 58-GC. volts. next connection in circuit
step. 58-GC, then repair.
10. Off If clearance lamp at Go to Replace defective
connector (522) does not next bulb.
illuminate, check bulb step.
filament. Bulb OK?
11. Off Disconnect connector (522), 58D 12 ±1.5 Go to Locate cause of low
(522). With headlight, and to gnd. volts. next or no voltage in circuit
cab and clearance lights step. 58D, then repair.
switches turned on, at
(522) measure voltage at
circuit 58D to ground.

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 12 LIGHT SYSTEMS 447

Table 142 Cab Clearance and Identification Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
12. Off At (522) measure voltage (522), 58D 12 ±1.5 Go to Locate open or poor
at circuit 58D to 58-GD. to 58-GD. volts. next connection in circuit
step. 58-GD, then repair.
13. Off If clearance lamp at Go to Replace defective
connector (523) does not next bulb.
illuminate, check bulb step.
filament. Bulb OK?
14. Off Disconnect connector (523), 58E 12 ±1.5 Go to Locate cause of low
(523). With headlight, and to gnd. volts. next or no voltage in circuit
cab and clearance lights step. 58E, then repair.
switches turned on, at
(523) measure voltage at
circuit 58E to ground.
15. Off At (523) measure voltage (523), 58E 12 ±1.5 Go to Locate open or poor
at circuit 58E to 58-GE. to 58-GE. volts. next connection in circuit
step. 58-GE, then repair.
16. Off If clearance lamp at Go to Replace defective
connector (524) does not next bulb.
illuminate, check bulb step.
filament. Bulb OK?
17. Off Disconnect connector (524), 58F 12 ±1.5 Go to Locate cause of low
(524). With headlight, and to gnd. volts. next or no voltage in circuit
cab and clearance lights step. 58F, then repair.
switches turned on, at
(524) measure voltage at
circuit 58F to ground.
18. Off At (524) measure voltage (524), 58F 12 ±1.5 Go to Locate open or poor
at circuit 58F to 58-GF. to 58-GF. volts. next connection in circuit
step. 58-GF, then repair.
19. Off Clearance and
identification lights circuits
test good.

3.4. CAB DOME, READING, AND COURTESY LIGHTS

Table 143 Cab Dome, Reading, and Courtesy Lights
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
1. Off Does the left reading light Go to Go to next step.
illuminate when switched Step 8.
on?

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448 12 LIGHT SYSTEMS

Table 143 Cab Dome, Reading, and Courtesy Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
2. Off Check filament of left Go to Replace bulb.
reading light. Filament next step.
OK?
3. Off Remove fuse F1-D and F1-D. <1 ohm. Go to Locate cause of
check fuse for open next step. overload condition,
condition. then repair. Replace
fuse.
4. Off Replace fuse F1-D and F1-D, 14AY 12 ±1.5 Go to Locate cause of
measure voltage from to gnd. volts. next step. low or no voltage in
14AY to gnd. circuit 14H or 14Y
from (B2) battery
stud, then repair.
5. Off At left reading light (312), 63R 12 ±1.5 Go to Locate cause of
disconnect connector to gnd. volts. next step. low or no voltage in
(312) and measure voltage circuit 63P or 63R
from 63R to gnd. from fuse F1-D, then
repair.
6. Off At connector (312) (312), 63R 12 ±1.5 Go to Locate open or poor
measure voltage from to 63-GR. volts. next step. connection in circuit
63R to 63-GR. 63R, 11-GAB, or
11-GB to ground
stud at right dash
panel, then repair.
7. Off Replace defective reading
light and switch assembly.
8. Off Does the right reading light Go to Go to next step.
illuminate when switched Step 15.
on?
9. Off Check filament of right Go to Replace bulb.
reading light. Filament next step.
OK?
10. Off Remove fuse F1-D and F1-D. <1 ohm. Go to Locate cause of
check fuse for open next step. overload condition,
condition. then repair. Replace
fuse.
11. Off Replace fuse F1-D and F1-D, 14AY 12 ±1.5 Go to Locate cause of
measure voltage from to gnd. volts. next step. low or no voltage in
14AY to gnd. circuit 14H or 14Y
from (B2) battery
stud, then repair.

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 12 LIGHT SYSTEMS 449

Table 143 Cab Dome, Reading, and Courtesy Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
12. Off At right reading light (311), 63T 12 ±1.5 Go to Locate cause of
disconnect connector (311) to gnd. volts. next step. low or no voltage in
and measure voltage from circuit 63P or 63T
63T to ground. from fuse F1-D, then
repair.
13. Off At connector (311) (311), 63T 12 ±1.5 Go to Locate open or poor
measure voltage from to 63-GT. volts. next step. connection in circuit
63T to 63-GT. 63T, 11-GAB, or
11-GB to ground
stud at right dash
panel, then repair.
14. Off Replace defective reading
light and switch assembly.
15. Off Does the dome light switch Go to Go to next step.
(442) indicator illuminate Step 19.
when switch is turned on?
16. Off Disconnect connector (428), 62AP 12 ±1.5 Go to Locate cause of
(428). Measure voltage to gnd. volts. next step. low or no voltage
at (428) circuit 62AP to in circuit 62A, 62S,
ground. or 62AP from panel
light switch (425),
then repair.
17. Off Disconnect connector (442), 63F 12 ±1.5 Go to Locate cause of
(442) and reconnect conn. to gnd. volts. next step. low or no voltage in
(428). Measure voltage at circuit 62AP or 63F,
(442) circuit 63F to ground. then repair.
18. Off Measure voltage at (442) (442), 63F 12 ±1.5 Replace Locate open or poor
circuit 63F to 62-GF. to 62-GF. volts. defective connection in circuit
dome 62-GF, 11-GAB, or
light 11-GB to ground
switch. stud at right dash
panel, then repair.
19. Off Do any of the dome or Go to Go to next step.
courtesy lights function Step 22.
with the dome light switch
set to on?
20. Off Remove fuse F2-B and F2-B. <1 ohm. Go to Locate cause of
check fuse for open next step. overload condition,
condition. then repair. Replace
fuse.

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450 12 LIGHT SYSTEMS

Table 143 Cab Dome, Reading, and Courtesy Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
21. Off Re-install fuse F2-B and F2-B, 14T 12 ±1.5 Go to Locate cause of
measure voltage from 14T to gnd. volts. next step. low or no voltage in
to ground. circuit 14AG or 14T
from (B2) battery
stud, then repair.
22. Do any of the dome or Go to Go to next step.
courtesy lights function Step 26.
with the left vehicle door
open, the right vehicle door
closed, and the dome light
set to automatic?
23. Off Remove connector (442) (442), 63B <1 ohm. Go to Go to next step.
from dome light switch. to gnd. Step 26.
With left vehicle door open,
and right door closed,
measure resistance from
circuit 63B to gnd.
24. Off Remove left door switch, Left door <1 ohm. Go to Replace defective
and measure resistance switch. next step. door switch, and
from connecting terminal to reconnect connector
mounting threads. (442). Go to Step
26.
25. Off Locate open in circuit 63B, Go to
or 63C between dome light next step.
switch and left door switch,
then repair.
26. Do any of the dome or Go to Go to next step.
courtesy lights function Step 30.
with the right vehicle door
open, the left vehicle door
closed, and the dome light
set to automatic?
27. Off With connector (442) (442), 63B <1 ohm. Go to Go to next step.
removed from dome light to gnd. Step 30.
switch and with right
vehicle door open, and
left door closed, measure
resistance from circuit 63B
to gnd.
28. Off Remove right door switch, Right door <1 ohm. Go to Replace defective
and measure resistance switch. next step. door switch, and
from connecting terminal to reconnect connector
mounting threads. (442). Go to Step
30.

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 12 LIGHT SYSTEMS 451

Table 143 Cab Dome, Reading, and Courtesy Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
29. Off Locate open in circuit 63B, Go to
or 63C between dome next step.
light switch and right door
switch, then repair.
30. Off With dome light switch Dome <1 ohm. Go to Replace dome
removed and in the switch, next step. light switch, and
automatic or door terminals, reconnect connector
switch position, measure 1 to 2. (442).
resistance between
terminals 1 and 2.
31. Off With dome light switch in Dome <1 ohm. Go to Replace dome
the on position, measure switch, next step. light switch, and
resistance between terminals, reconnect connector
terminals 2 and 3. 2 to 3. (442).
32. Off Re-install dome light Go to
switch. next step.
33. Off With a door open, does the Go to Go to next step.
left dome light illuminate? Step 38.
34. Off Check filament of left dome Go to Replace bulb.
light. Filament OK? next step.
35. Off At left dome light (116), 63M 12 ±1.5 Go to Locate cause of
disconnect connector to gnd. volts. next step. low or no voltage in
(116) and measure voltage circuit 63, 63Z, 63,
from 63M to ground. or 63M to fuse F2-B,
then repair.
36. Off At connector (116) (116), 63M 12 ±1.5 Go to Locate open or poor
measure voltage from to 63N. volts. next step. connection in circuit
63M to 63N. 63N to dome light
switch, then repair.
37. Off Replace defective left Go to
dome light assembly. next step.
38. Off With a door open, does the Go to Go to next step.
right dome light illuminate? Step 43.
39. Off Check filament of right Go to Replace bulb.
dome light. Filament OK? next step.
40. Off At right dome light (115), 63S 12 ±1.5 Go to Locate cause of
disconnect connector to gnd. volts. next step. low or no voltage in
(115) and measure voltage circuit 63S, 63, 63Z
from 63S to ground. or 63 to fuse F2-B,
then repair.

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452 12 LIGHT SYSTEMS

Table 143 Cab Dome, Reading, and Courtesy Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
41. Off At connector (115) (115), 63S 12 ±1.5 Go to Locate open or poor
measure voltage from to 63Y. volts. next step. connection in circuit
63S to 63Y. 63Y or 63A to dome
light switch, then
repair.
42. Off Replace defective right Go to
dome light assembly. next step.
43. Off With a door open, does Go to Go to next step.
the left courtesy light Step 48.
illuminate?
44. Off Check filament of left Go to Replace bulb.
courtesy light. Filament next step.
OK?
45. Off At left courtesy light (100), 63V 12 ±1.5 Go to Locate cause of
disconnect connector (100) to gnd. volts. next step. low or no voltage in
and measure voltage from circuit 63 and 63V
63V to ground. to fuse F2-B, then
repair.
46. Off At connector (100) (100), 63V 12 ±1.5 Go to Locate open or poor
measure voltage from to 63H. volts. next step. connection in circuit
63V to 63H. 63H or 63A to dome
light switch, then
repair.
47. Off Replace defective left Go to
courtesy light assembly. next step.
48. Off With a door open, does Go to Go to next step.
the right courtesy light Step 53.
illuminate?
49. Off Check filament of right Go to Replace bulb.
courtesy light. Filament next step.
OK?
50. Off At right courtesy light (100), 63V 12 ±1.5 Go to Locate cause of
disconnect connector (100) to gnd. volts. next step. low or no voltage in
and measure voltage from circuit 63, 63X, or
63V to ground. 63V to fuse F2-B,
then repair.
51. Off At connector (100) (100), 63V 12 ±1.5 Go to Locate open or poor
measure voltage from to 63H. volts. next step. connection in circuit
63V to 63H. 63H, 63Y or 63A to
dome light switch,
then repair.

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 12 LIGHT SYSTEMS 453

Table 143 Cab Dome, Reading, and Courtesy Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF
POINTS SPEC. SPEC.
52. Off Replace defective right Go to
courtesy light assembly. next step.
53. Off Cab dome, reading, and
courtesy lights check good.

3.5. DAYTIME RUNNING LIGHTS (DRL) MODULE WIRING- STANDARD USA AND
CANADA
Table 144 Daytime Running Lights (DRL) Module Wiring-Standard USA and Canada
STEP KEY ACTION TEST SPEC. YES NO - OUT OF SPEC.
POINTS - IN
SPEC.
1. Off Remove fuse F10-B and F10-B. <1 ohm. Go to Locate cause of
check for open condition. next overload condition,
step. then repair. Replace
fuse.
2. Off Re-install fuse F10-B. At F10-B, 14BL 12 ±1.5 Go to Locate cause of low
F10-B measure voltage to gnd. volts. next or no voltage in circuit
from circuit 14BL to step. 14BL to (B1) battery
ground. adapter, then repair.
3. Off Remove connector (513) (513), 66A to 12 ±1.5 Go to Locate cause of low
from DRL module, and gnd. volts next or no voltage in circuit
measure voltage from step. 66A, then repair.
circuit 66A to ground.
4. Off Check fuse F10-A for F10-A. <1 ohm. Go to Locate cause of
open condition. next overload condition,
step. then repair. Replace
fuse.
5. Off Turn ignition key on F10-A, 13BL 12 ±1.5 Go to Locate cause of low
and at F10-A measure to gnd. volts. next or no voltage in circuit
voltage from circuit 13BL step. 13BL from I2 ignition
to ground. adapter, then repair.
6. Off Measure voltage from (513), 66D to 12 ±1.5 Go to Locate cause of low
circuit 66D to ground. gnd. volts. next or no voltage in circuit
step. 66D, then repair.
7. Off Remove connector (468) (468), 44-GB <1 ohm. Go to Locate open or poor
from DRL park brake to gnd. next connection in circuit
switch and measure step. 44-GB or 66-G, then
resistance from circuit repair.
44-GB to ground.

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454 12 LIGHT SYSTEMS

Table 144 Daytime Running Lights (DRL) Module Wiring-Standard USA and Canada (cont.)
STEP KEY ACTION TEST SPEC. YES NO - OUT OF SPEC.
POINTS - IN
SPEC.
8. Off With park brake applied, Across DRL <1 ohm. Go to Replace defective
measure resistance park brake next DRL park brake
across DRL park brake switch. step. switch.
switch.
9. Off Chock vehicle wheels Across DRL >100K Go to Re-apply park brake.
and release park brake. park brake ohms. next Replace defective
Measure resistance switch. step. DRL park brake
across DRL park brake switch.
switch.
10. Off/On Reconnect (513). When Go to Go to next step.
ign. key is moved/held Step 17.
to start position, does
park brake indicator
illuminate?
11. Off Check fuse F4-A for open F4-A. <1 ohm. Go to Locate cause of
condition. next overload condition,
step. then repair. Replace
fuse.
12. Off At F4-A measure voltage F4-A, 13B 12 ±1.5 Go to Locate cause of
from circuit 13B to to gnd. volts next low or no voltage in
ground. step. circuit 13 or 13B from
ignition key switch,
then repair.
13. Off/On Remove conn. (420) (420), 28C to 12 ±1.5 Go to Locate cause of low
With key in on (ign.) gnd. volts. next or no voltage in circuit
position at conn. (420) step. 13V or 28C to ign. key
measure voltage from switch, then repair.
circuit 28C to ground.
14. Off Check filament of park Go to Replace lamp, and
brake lamp for open next reconnect (420).
condition. Lamp OK? step.
15. Off With park brake applied, (420), 44 to < 1 ohm. Go to Locate open or poor
at connector (420) gnd. next connection in circuit
measure resistance from step. 44, 44A or 44B to DRL
circuit 44 to ground. park brake switch and
circuits checked in
steps above, then
repair.
16. Off/On Reconnect conn. (420), Go to Replace defective
move key to start (crank) next ignition key switch.
position. Does lamp step.
illuminate?

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 12 LIGHT SYSTEMS 455

Table 144 Daytime Running Lights (DRL) Module Wiring-Standard USA and Canada (cont.)
STEP KEY ACTION TEST SPEC. YES NO - OUT OF SPEC.
POINTS - IN
SPEC.
17. Off Park brake lamp circuits Go to
check good. next
step.
18. Off Remove connector (513) (513), 66-GA <1 ohm. Go to Locate open or poor
from DRL module. to gnd. next connection in circuit
At (513) measure step. 66-GA, then repair.
resistance from circuit
66-GA to ground.
19. Off With park brake applied, (513), 66-E to <1 ohm. Go to Locate open or poor
at (513) measure gnd. next connection in circuit
resistance from circuit step. 66-E, then repair.
66-E to ground.
20. Off Remove connector (440) (440), 64C to <1 ohm. Recon- Locate open or poor
from fog light switch, and (513) 64D. nect connection in circuit
measure resistance from (440). 64C or 64D, then
circuit 64C at (440) to Go to repair.
circuit 64D at connector next
(513). step.
21. Off Move headlight switch (513), 66B to 12 ±1.5 Go to Locate cause of low
to on and dimmer switch gnd. volts. next or no voltage in circuit
to low beam position. At step. 64C or 66B, then
(513) and circuit 66B, repair.
measure voltage to
ground.
22. Off With headlight switch on (513), 66F to 12 ±1.5 Go to Locate open or poor
and dimmer switch in gnd. volts. next connection in circuit
high position, measure step. 66F, then repair.
voltage at connector
(513) circuit 66F to
ground.
23. Off Daytime running light
circuits check good. If
system does not operate
properly, replace DRL
module. Reconnect
connectors (468) and
(513).

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456 12 LIGHT SYSTEMS

3.6. FOG LIGHTS

Table 145 Fog Lights
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off Remove conn. (440) (440), 64C 12 ±1.5 Go to Locate cause of low
from fog light switch. to gnd. volts. next or no voltage in circuit
Move headlight sw. to on step. 64C, then repair.
position, and place dimmer
sw. in low beam position.
At (440) measure voltage
from circuit 64C to ground.
2. Off With fog light switch in Fog light <1 ohm. Go to Replace defective
the on position, measure switch, 5 to next switch, reconnect
resistance across terminals 6. step. connector (440).
5 and 6.
3. Off Was the on indicator of the Go to Go to next step.
fog light switch functional Step 5.
prior to removal?
4. Off Use diode test function on Fog light .7V diode Go to Replace defective
Fluke meter to test. Does switch, 1 to drop. next switch, reconnect
indicator check good? 3. step. connector (440).
5. Off Was the switch panel light Go to Go to next step.
indictor of the fog light Step 7.
switch functional prior to
removal?
6. Off Use diode test function on Fog light .7V diode Go to Replace defective
Fluke meter to test. Does switch, 7 to drop. next switch, reconnect
panel lamp check good? 8. step. connector (440).
7. Off With headlight switch on (440), 64C 12 ±1.5 Go to Locate open or poor
and dimmer switch in low to 64-G. volts. next connection in circuit
beam position, at (440) step. 64-G, or 11-GAC to
measure voltage from ground adapter (455),
circuit 64C to 64-G. then repair.
8. Off With headlight switch on, (440), 12 ±1.5 Go to Locate cause of low
at (440) measure voltage 62AN to volts. next or no voltage in circuit
from circuit 62AN to 64-G. 64-G. step. 62AN, then repair.
9. Off With headlight switch (440), 12 ±1.5 Go to Locate open or poor
on, at (440) measure 62AN to volts. next connection in circuit
voltage from circuit 62AN 64- GAN. step. 62-GAN, then repair.
to 62-GAN.
10. Off Turn headlight switch off, Go to
re-install fog light switch next
(440) and remove relay step.
(148).

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 12 LIGHT SYSTEMS 457

Table 145 Fog Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
11. Off Turn headlight switch on (148), 64A 12 ±1.5 Go to Locate cause of low
and with dimmer switch to gnd. volts. next or no voltage in circuit
in low beam position, at step. 64A, then repair.
(148) measure voltage
from circuit 64A to ground.
12. Off Turn headlight switch on (148), 64A 12 ±1.5 Go to Locate open or poor
and with dimmer switch to 64-GA. volts. next connection in circuit
in low beam position, at step. 64GA, 64-GB, or
(148) measure voltage 11-GAC to ground
from circuit 64A to 64-GA. adapter (455), then
repair.
13. Off Check fuse F10-A for open F10-A. <1 ohm. Go to Locate cause of
condition. next overload condition,
step. then repair. Replace
fuse.
14. On At F10-A measure voltage F10-A, 12P 12 ±1.5 Go to Locate cause of low
from circuit 12P to ground. to gnd. volts. next or no voltage in circuit
step. 12P from accessory
adapter (501), then
repair.
15. On At connector (148) (148), 64 to 12 ±1.5 Go to Locate cause of low
measure voltage from gnd. volts. next or no voltage in circuit
circuit 64 to ground. step. 64, then repair.
16. Off At connector (148) use test Replace Go to next step.
jumper to connect circuit 64 fog light
to 64B. With headlights on, relay
do the fog lights illuminate? (148).
17. Off Turn headlights off. (1), M to 12 ±1.5 Go to Locate cause of no or
Disconnect conn. (1). With gnd. volts. next low voltage in circuit
jumper still in place turn step. 64B, then repair.
headlights on and measure Remove jumper and
voltage at connector (1) re-install fog light
terminal M to gnd. relay.
18. Off Turn headlights off. (1), 64B to 12 ±1.5 Go to Locate cause of no or
Reconnect conn. (1) gnd. volts next low voltage in circuit
and disconnect conn. (1). step. 64B, then repair.
Turn headlights on and Remove jumper and
at (1), with jumper still in re-install fog light
place, measure voltage at relay.
circuit 64B to ground.

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458 12 LIGHT SYSTEMS

Table 145 Fog Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
19. Off Turn headlights off and (65), 64D 12 ±1.5 Go to Locate cause of no
disconnect connector (65). to gnd. volts. next or low voltage in
Turn headlights on and step. circuit 64B or 64D,
measure voltage at circuit then repair. Remove
64D to ground. jumper and re-install
fog light relay.
20. Off Turn headlights off and (66), 64C 12 ±1.5 Go to Locate cause of no
disconnect connector (66). to gnd. volts. next or low voltage in
Turn headlights on and step. circuit 64B or 64C,
measure voltage at circuit then repair. Remove
64C to ground. jumper and re-install
fog light relay.
21. Off With headlights on, (65), 64D 12 ±1.5 Go to Locate open or poor
measure voltage at to 64-GB. volts next connection in circuit
connector (65) circuit step. 64-GB or 64-GC
64D to 64-GB. to cab ground J7,
then repair. Remove
jumper and re-install
fog light relay.
22. Off With headlights on, (66), 64C 12 ±1.5 Fog Locate open or poor
measure voltage at conn. to 64-GA. volts. lights connection in circuit
(66) circuit 64C to 64-GA. circuits 64-GA or 64-GC
check to cab ground J7,
good. then repair. Remove
jumper and re-install
fog light relay.

3.7. HEADLIGHT SWITCH AND DIMMER SWITCH WIRING

Table 146 Headlight Switch and Dimmer Switch Wiring
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off Check circuit breaker F8-B F8-B. <1 ohm. Go to next Locate cause of
for open condition. step. overload condition,
then repair. Replace
fuse.
2. Off At F8-B measure voltage F8-B, 12 ±1.5 Go to next Locate cause of low
from circuit 14D to ground. 14D to volts. step. or no voltage in circuit
gnd. 14H or 14D from
battery stud (B2),
then repair.
3. Off Remove headlight relay (462- R4), 12 ±1.5 Go to next Locate cause of low
(462-R4). At circuit 51 51 to gnd. volts. step. or no voltage in circuit
measure voltage to gnd. 51, then repair.

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 12 LIGHT SYSTEMS 459

Table 146 Headlight Switch and Dimmer Switch Wiring (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
4. Off Remove and check fuse F8-A. <1 ohm. Go to next Locate cause of
F8-A for open condition. step. overload condition,
then repair. Replace
fuse.
5. Off Re-install fuse F8-A. At F8-A, 12 ±1.5 Go to next Locate cause of low
F8-A measure voltage from 14D to volts. step. or no voltage in circuit
circuit 14D to ground. gnd. 14H or 14D from
battery stud (B2),
then repair.
6. Off Remove conn. (465) from (465), 50 12 ±1.5 Go to next Locate cause of low
headlight switch. At circuit to gnd. volts. step. or no voltage in circuit
50 measure voltage to 50, then repair.
ground.
7. Off Check circuit breaker F3-D F3-D. <1 ohm. Go to next Locate cause of
for open condition. step. overload condition,
then repair. Replace
fuse.
8. Off At F3-D measure voltage F3-D, 12 ±1.5 Go to next Locate cause of low
from circuit 14B to ground. 14B to volts. step. or no voltage in circuit
gnd. 14H or 14B from
battery stud (B2),
then repair.
9. Off At circuit 50A of connector (465), 12 ±1.5 Go to next Locate cause of low
(465) measure voltage to 50A to volts. step. or no voltage in circuit
ground. gnd. 50A, then repair.
10. Off With headlight and cab and (465), 12 ±1.5 Go to next Locate cause of
trailer lights switches in on 62AS to volts step. low or no voltage in
position, at conn. (465) gnd. circuit 62A, 62S, or
measure voltage from 62AS from panel light
circuit 62AS to ground. switch, then repair.
Re-install headlight
switch.
11. Off With switches still on , (465), 12 ±1.5 Go to next Locate open or poor
at conn. (465) measure 62AS to volts. step. connection in circuit
voltage from circuit 62AS 62- GAS. 62-GAS, 11-GK, or
to 62-GAS. 11-GD to ground stud
at left dash panel,
then repair. Re-install
headlight switch.
12. Off With headlight switch in Headlight <1 ohm. Go to next Replace defective
the on position, measure switch, 2 step. switch, reconnect
resistance across terminals to 3. connector (465).
2 and 3.

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460 12 LIGHT SYSTEMS

Table 146 Headlight Switch and Dimmer Switch Wiring (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
13. Off With headlight switch in Headlight <1 ohm. Go to next Replace defective
the on position, measure switch, 5 step. switch, reconnect
resistance across terminals to 6. connector (465).
5 and 6.
14. Off With headlight switch in Headlight <1 ohm. Go to next Replace defective
the park light position, switch, 1 step. switch, reconnect
measure resistance across to 2. connector (465).
terminals 1 and 2.
15. Off Was headlight switch panel Go to Step Go to next step.
lamp functional prior to 17.
removal?
16. Off Use diode test function on Headlight .7V diode Go to next Replace defective
Fluke meter to test. Does switch, 7 drop. step. switch, reconnect
panel lamp check good? to 8. connector (465).
17. Off Reconnect headlight switch Go to next
(465). step.
18. Off With headlight relay (462 -R4), 12 ±1.5 Go to next Locate cause of low
removed and headlight 50B to volts. step. or no voltage in circuit
switch in the on position, at gnd. 50B, then repair.
(462-R4) measure voltage Re-install headlight
from circuit 50B to gnd. relay.
19. Off With headlight switch still (462 -R4), 12 ±1.5 Go to next Locate open or poor
on, measure voltage at 50B to volts. step. conn. in circuit
connector (462-R4) for 50-GB. 50-GB, or 11-G to
circuit 50B to 50-GB. ground stud at right
dash panel, then
repair. Re-install
headlight relay.
20. Off Turn headlight switch off, (42), 51A 12 ±1.5 Go to next Locate cause of low
and install a test jumper to gnd. volts. step. or no voltage in circuit
at relay socket (462-R4) 51A, then repair.
from circuit 51 to 51A. Re-install headlight
Disconnect conn. (42), turn relay.
on the headlight switch,
and measure voltage from
circuit 51A to gnd.
21. Off Turn off headlight switch (42), 51A 12 ±1.5 Go to next Replace defective
and re-install headlight to gnd volts. step. headlight relay, and
relay at (462-R4). Then reconnect (42).
turn on headlight switch
and at (42) measure
voltage from circuit 51A to
ground.

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 12 LIGHT SYSTEMS 461

Table 146 Headlight Switch and Dimmer Switch Wiring (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
22. Off With dimmer switch in Dimmer <1 ohm. Go to next Replace defective
the low position, measure sw., red to step. switch, reconnect
resistance between red blue wire. connector (42).
wire and blue wire.
23. Off With dimmer switch in the Dimmer <1 ohm. Go to next Replace defective
high position, measure sw., red step. switch, reconnect
resistance between red to brown connector (42).
wire and brown wire. wire.
24. Off Reconnect conn. (42). Go to step Go to next step.
With headlight switch 29.
turned on and dimmer
switch in high beam
position, does the high
beam indicator illuminate?
25. Off With headlight switch off (421) , 12 ±1.5 Go to next Locate cause of low
disconnect conn. (421). 52J to volts. step. or no voltage in circuit
Turn headlight and high gnd. 52B or 52J, then
beam switches on and repair.
measure voltage at conn.
(421) circuit 52J to ground.
26. Off With switches still on (421), 12 ±1.5 Go to next Locate open or poor
measure voltage at (421) 52J to volts. step. connection in circuit
for circuits 52J to 62-GD. 62-GD. 62-GD or 11-GF, then
repair.
27. Off Replace defective high Go to next
beam indicator lamp or step.
socket assembly.
28. Off With headlight switch off , (1), 52F 12 ±1.5 Go to next Locate cause of low
disconnect conn. (1). Then to gnd. volts. step. or no voltage in circuit
turn headlight switch on 52F, then repair.
and place dimmer switch in
high beam position, and at
(1) measure voltage from
circuit 52F to ground.
29. Off With headlight switch on (1), 53B 12 ±1.5 Go to next Locate cause of low
and dimmer switch in to gnd. volts. step. or no voltage in circuit
low beam position. At 53B, then repair.
(1) measure voltage from
circuit 53B to gnd.
30. Off With headlight switch off, (1), <1 ohm. Headlight Locate open or poor
at (1) measure resistance 52-GE to and connection in circuit
from circuit 52-GE to gnd. dimmer 52-GE, 52-GF, or
ground. switch 11-GF to ground stud
circuits

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462 12 LIGHT SYSTEMS

Table 146 Headlight Switch and Dimmer Switch Wiring (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
check at left dash panel,
good. then repair.

3.8. HEADLIGHTS
Table 147 Headlights
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off With headlight switch off, (1), 52F 12 ±1.5 Go to next Locate cause of low
disconnect conn. (1). Then to gnd. volts. step. or no voltage in circuit
turn headlight switch on 52F, then repair.
and place dimmer switch in
high beam position, and at
(1) measure voltage from
circuit 52F to ground.
2. Off With headlight switch on (1), 53B 12 ±1.5 Go to next Locate cause of low
and dimmer switch in to gnd. volts. step. or no voltage in circuit
low beam position. At 53B, then repair.
(1) measure voltage from
circuit 53B to gnd.
3. Off With headlight switch off (1), <1 ohm. Switch Locate open or poor
at (1) measure resistance 52-GE to circuits connection in circuit
from circuit 52-GE to gnd. check 52-GE, 52-GF, or
ground. good. Go 11-GF to ground stud
to next at left dash panel,
step. then repair.
4. Off Turn off headlight switch. (296), 12 ±1.5 Go to next Locate cause of low
Reconnect connector (1), 53D to volts. step. or no voltage in circuit
and disconnect connector gnd. 53B or 53D, then
(296). Turn headlight repair.
switch on and place
dimmer switch in low beam
position. Measure voltage
at (296) from circuit 53D to
gnd.
5. Off With headlight switch still (296), 12 ±1.5 Go to next Locate cause of low
on, place dimmer switch 52D to volts. step. or no voltage in circuit
in high beam position. gnd. 52F or 52D, then
Measure voltage at (296) repair.
from circuit 52D to gnd.
6. Off With headlight switch still (296), 12 ± 1.5 Go to next Locate open or poor
on and dimmer sw. in high 52D to volts. step. conn. in circuit
beam position, measure 52-GE. 52-GE, then repair.
voltage at (296) from circuit
52D to 52-GE.

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 12 LIGHT SYSTEMS 463

Table 147 Headlights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
7. Off Turn off headlight switch. (77), 12 ± 1.5 Go to next Locate cause of low
Reconnect conn. (296) yellow 2 volts. step. or no voltage in yellow
and disconnect conn. (77). wire to 2 wire, then repair.
Turn on headlight switch gnd.
and place dimmer switch
in low beam position. At
(77) measure voltage from
yellow 2 wire to ground.
8. Off With headlight switch on, (77), 12 ± 1.5 Go to next Locate cause of low
place dimmer switch in yellow 1 volts. step. or no voltage in yellow
high beam position. At wire to 1 wire, then repair.
(77) measure voltage from gnd.
yellow 1 wire to ground.
9. Off With headlight switch on, (77), 12 ±1.5 Go to next Locate open or poor
and dimmer switch in high yellow 1 volts. step. connection in white 2
beam position, at (77) wire to or yellow 1 wire, then
measure voltage from white 2 repair.
yellow 1 wire to white 2 wire.
wire.
10. Off Turn off headlight switch. (211), 12 ± 1.5 Go to next Locate cause of low
Disconnect conn. (211). 53C to volts. step. or no voltage in circuit
Turn on headlight switch gnd. 53C, then repair.
and place dimmer switch
in low beam position. At
(211) measure voltage
from circuit 53C to gnd.
11. Off With headlight switch on, (211), 12 ±1.5 Go to next Locate cause of low
place dimmer switch in 52E to volts. step. or no voltage in circuit
high beam position. At gnd. 52E, then repair.
(211) measure voltage
from circuit 52E to ground.
12. Off With headlight switch on, (211), 12 ± 1.5 Go to next Locate open or poor
and dimmer switch in high 52E to volts. step. conn. in circuit
beam position, at (211) 52-GA. 52-GA, or circuit
measure voltage from 64-GC to cab ground
circuit 52E to 52-GA. J7, then repair.
13. Off Turn off headlight switch, Go to next
and reconnect connector step.
(211).
14. Off Disconnect conn. (71). (71), 12 ± 1.5 Go to next Locate cause of low
Turn on headlight switch yellow 2 volts. step. or no voltage in yellow
and place dimmer switch wire to 2 wire, then repair.
in low beam position. At gnd.
(71) measure voltage from
yellow 2 wire to ground.

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464 12 LIGHT SYSTEMS

Table 147 Headlights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
15. Off With headlight switch on, (71), 12 ± 1.5 Go to next Locate cause of low
place dimmer switch in yellow 1 volts. step. or no voltage in yellow
high beam position. At wire to 1 wire, then repair.
(71) measure voltage from gnd.
yellow 1 wire to ground.
16. Off With headlight switch on, (71), 12 ± 1.5 Go to next Locate open or poor
and dimmer switch in high yellow 1 volts. step. connection in white 2
beam position, at (71) wire to or yellow 1 wire, then
measure voltage from white 2 repair.
yellow 1 wire to white 2 wire.
wire.
17. Off Headlight circuits check
good.

3.9. PANEL LIGHTS

Table 148 Panel Lights
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off With headlight switch in the F8-C. <1 ohm. Go to next Locate cause of
off position, check fuse F8-C step. overload condition,
for open condition. then repair. Replace
fuse.
2. Off At F8-C measure voltage F8-C, 68D 12 ± 1.5 Go to next Locate cause of low
from circuit 68D to ground. to gnd. volts. step. or no voltage in circuit
68D or 68E from cab
and trailer lights
relay, then repair.
3. Off Disconnect connector (425) (425), 62 12 ± 1.5 Go to next Locate cause of low
from panel light switch. to gnd. volts. step. or no voltage in circuit
Move headlight switch to 68C or 62 from F8-C,
on, and measure voltage at then repair.
(425) circuit 62 to gnd.
4. Off Was panel light switch panel Go to Step Go to next step.
lamp functional prior to 6.
removal?
5. Off Use diode test function on Panel light .6 to .8V Go to next Replace defective
Fluke meter to test. Does switch, F diode step. switch, reconnect
panel lamp check good? to D. drop. connector (425).

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 12 LIGHT SYSTEMS 465

Table 148 Panel Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
6. Off At (425), measure voltage (425), 62 12 ± 1.5 Go to next Locate open or poor
from circuit 62 to 62-GW. to 62-GW. volts. step. connection in circuit
62-GW, 11-GK, or
11-GD to ground stud
at left dash panel,
then repair.
7. Off At (425), measure voltage (425), 62 12 ± 1.5 Go to next Locate open or poor
from circuit 62 to 11-GS. to 11-GS. volts. step. connection in circuit
11-GS, then repair.
8. Off Install test jumper between Go to next
circuits 62 and 62A, then step.
turn on headlight switch.
9. Off Does the cigar lighter panel Go to Step Go to next step.
light illuminate? 11.
10. Off Turn off headlight switch, 62T to 12 ± 1.5 Replace Locate cause of
disconnect wire to cigar gnd. volts. cigar low or no voltage in
lighter panel lamp holder. lighter circuit 62A or 62T,
Turn on headlight switch and lamp. Go then repair.
measure voltage from circuit to next
62T to ground. step.
11. Off Does the heater control Go to Step Go to next step.
panel light illuminate? 14.
12. Off Turn off headlight switch, 62P to 12 ± 1.5 Go to next Locate cause of low
remove bulb from heater gnd. volts. step. or no voltage in circuit
control panel lamp holder. 62S or 62PS, then
Turn on headlight switch and repair.
measure voltage from circuit
62P to gnd.
13. Off Measure voltage from circuit 62P to 12 ± 1.5 Replace Locate open or poor
62P to circuit 62-GP. 62-GP. volts. heater connection in circuit
control 62-GP or 11-G to
lamp. Go ground stud at right
to next dash panel, then
step. repair.
14. Off Do any of the right Go to Step Go to next step.
gauge cluster panel lights 18.
illuminate?
15. Off Turn off headlight switch, (420), 62B 12 ± 1.5 Go to next Locate cause of low
disconnect connector (420), to gnd. volts. step. or no voltage in circuit
turn on headlight switch, and 62B, then repair.
measure voltage from circuit
62B to ground.

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466 12 LIGHT SYSTEMS

Table 148 Panel Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
16. Off Measure voltage from circuit 62B to 12 ± 1.5 Go to next Locate open or poor
62B to circuit 62-GB. 62-GB. volts. step. connection in circuit
62-GB or 11-GF to
ground stud at left
dash panel, then
repair.
17. Off Replace defective lamp(s) or Go to next
lamp holders. step.
18. Off Do any of the left gauge Go to Step Go to next step.
cluster panel lights 22.
illuminate?
19. Off Turn off headlight switch, (423), 62C 12 ± 1.5 Go to next Locate cause of low
disconnect connector (423), to gnd. volts. step. or no voltage in circuit
turn on headlight switch, and 62C, then repair.
measure voltage from circuit
62C to ground.
20. Off Measure voltage from circuit 62C to 12 ± 1.5 Go to next Locate open or poor
62C to circuit 62-GC. 62-GC. volts. step. connection in circuit
62-GC, then repair.
21. Off Replace defective lamp(s) or Go to next
lamp holders. step.
22. Off Do any of the speedo/tach Go to step Go to next step.
module panel lights 26.
illuminate?
23. Off Turn off headlight switch, (421), 62D 12 ± 1.5 Go to next Locate cause of low
disconnect connector (421), to gnd. volts. step. or no voltage in circuit
turn on headlight switch, and 62D, then repair.
measure voltage from circuit
62D to gnd.
24. Off Measure voltage from circuit 62D to 12 ± 1.5 Go to next Locate open or poor
62D to circuit 62-GD. 62-GD. volts. step. connection in circuit
62-GD, then repair.
25. Off Replace defective lamp(s) or Go to next
lamp holders. step.
26. Off Do either the analog clock or Go to Step Go to next step.
air restriction gauge panel 32.
lights illuminate?
27. Off Turn on headlight switch, (503), 12 ± 1.5 Go to next Locate cause of
and measure voltage at 62M to volts. step. low or no voltage in
panel lights feed adapter gnd. circuit 62M or 62S,
(503) circuit 62M to gnd. then repair.

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 12 LIGHT SYSTEMS 467

Table 148 Panel Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
28. Off Turn off headlight switch, (560), 12 ± 1.5 Go to next Locate cause of
and disconnect air restriction 62AB to volts. step. low or no voltage in
gauge connector (560). gnd. circuit 62AB coming
Move headlight switch to on from panel lights feed
and measure voltage from adapter (503), then
circuit 62AB to ground. repair.
29. Off With headlight switch still on, (560), 12 ± 1.5 Replace Locate open or poor
measure voltage between 62AB to volts. defective connection in circuit
circuit 62AB and 62-GAB. 62- GAB. panel 62-GAB going to
lamp. Go panel lights ground
to next adapter (506), then
step. repair.
30. Off Turn off headlight switch, 62AQ to 12 ± 1.5 Go to next Locate cause of
and remove analog clock gnd. volts. step. low or no voltage in
panel lamp. Move headlight circuit 62AQ coming
switch to on and measure from panel lights feed
voltage from circuit 62AQ to adapter (503), then
gnd. repair.
31. Off With headlight switch still on, 62AQ to 12 ± 1.5 Replace Locate open or poor
measure voltage between 62- GAQ. volts. defective connection in circuit
circuit 62AQ and 62-GAQ. panel 62-GAQ or 11-GAV
lamp. Go going to ground
to next adapter (454), then
step. repair.
32. Off Panel light circuits check
good.

3.10. PARK/TURN/MARKER LIGHTS

Table 149 Park/Turn/Marker Lights
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off With headlight switch in F8-C. <1 ohm. Go to Locate cause of
the off position, check fuse next overload condition,
F8-C for open condition. step. replace fuse.
2. Off Move headlight switch to F8-C, 68D 12 ± 1.5 Go to Locate cause of low or
the on position. At F8-C to gnd. volts. next no voltage in circuit 68E
measure voltage from step. or 68D from cab and
circuit 68D to ground. trailer tail lights relay,
then repair.

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468 12 LIGHT SYSTEMS

Table 149 Park/Turn/Marker Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
3. Off Move headlight switch (1), 58H to 12 ± 1.5 Go to Locate cause of low or
to the off position, and gnd. volts. next no voltage in circuit 68C
disconnect connector (1). step. or 58H, then repair.
Turn headlight switch on,
and at circuit 58H measure
voltage to ground.
4. Off Move headlight switch (296), 58T 12 ± 1.5 Go to Locate cause of low or
to the off position, and to gnd. volts. next no voltage in circuit 58H
reconnect connector (1). step. or 58T, then repair.
Disconnect connector
(296), turn headlight
switch on, and at circuit
58T measure voltage to
ground.
5. Off With headlight switch on, at (296), 58T 12 ± 1.5 Go to Locate open or poor
connector (296) measure to 52-GE. volts. next connection in circuit
voltage from 58T to 52-GE. step. 52-GE, conn. (1), circuit
52-GE, 52-GF, or 11-GF
to left dash gnd. stud,
then repair.
6. Off With (296) reconnected, if Go to
left marker lamp does not next
illuminate replace defective step.
bulb or socket.
7. Off Move headlight switch to (211), 58U 12 ± 1.5 Go to Locate cause of low
the off position. Disconnect to gnd. volts. next or no voltage in circuit
connector (211), turn step. 58U, then repair.
headlight switch on, and
at circuit 58U measure
voltage to ground.
8. Off With headlight switch on, at (211), 58U 12 ± 1.5 Go to Locate open or poor
connector (211) measure to 64-GC. volts. next connection in circuit
voltage from 58U to 64-GC. step. 64-GC, then repair.
9. Off With (211) reconnected, if Go to
right marker lamp does not next
illuminate replace defective step.
bulb or socket.
10. Off With the turn signal Go to
switch in the off position, next
disconnect turn signal step.
flasher and install a test
jumper wire.

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 12 LIGHT SYSTEMS 469

Table 149 Park/Turn/Marker Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
11. Off Disconnect connector (170), 56D 12 ± 1.5 Go to Locate cause of low or
(170), move turn signal to gnd. volts. next no voltage in circuit 56D
indicator to left turn step. from turn signal switch,
position, and measure then repair.
voltage from circuit 56D to
ground.
12. Off At connector (170), with (170), 56D 12 ± 1.5 Go to Locate open or poor
turn signal indicator in the to 56-GA. volts. next connection in circuit
left turn position, measure step. 56-GA or 11-GD to left
voltage from circuit 56D to dash panel ground stud.
56-GA.
13. Off With (170) reconnected, if Go to
left side turn light does not next
illuminate replace defective step.
bulb or socket.
14. Off Disconnect connector (171), 57D 12 ± 1.5 Go to Locate cause of low or
(171) and move turn signal to gnd. volts. next no voltage in circuit 57D
indicator to right turn step. from turn signal switch,
position. With test jumper then repair.
(step 10) still installed,
measure voltage from
circuit 57D to gnd.
15. Off At connector (171), with (171), 57D 12 ± 1.5 Go to Locate open or poor
turn signal indicator in the to 57-GA. volts. next connection in circuit
right turn position, measure step. 57-GA or 11-GB to right
voltage from circuit 57D to dash panel ground stud.
57-GA.
16. Off With (171) reconnected, if Go to
right side turn light does not next
illuminate replace defective step.
bulb or socket.
17. Off Disconnect connector (296), 56 12 ± 1.5 Go to Locate cause of low or
(296) and move turn to gnd. volts. next no voltage in circuit 56,
signal indicator to left turn step. connector (1), or circuit
position. With test jumper 56 from turn signal
(step 10) still installed, switch, then repair.
measure voltage from
circuit 56 to gnd.
18. Off With (296) reconnected, if Go to
left side turn light does not next
illuminate replace defective step.
bulb or socket.

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470 12 LIGHT SYSTEMS

Table 149 Park/Turn/Marker Lights (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
19. Off Disconnect connector (211), 57 12 ± 1.5 Go to Locate cause of low or
(211) and move turn signal to gnd. volts. next no voltage in circuit 57,
indicator to right turn step. connector (1), or circuit
position. With test jumper 57 from turn signal
(Step 10) still installed, switch, then repair.
measure voltage from
circuit 57 to gnd.
20. Off With (211) reconnected, if Go to
right side turn light does not next
illuminate replace defective step.
bulb or socket.
21. Off Park, turn, and side marker
light circuits check good.

3.11. SPOTLIGHT
Table 150 Spotlight
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F1-D and F1-D. <1 ohm. Go to Locate cause of
check for open condition. next overload condition
step. and replace fuse.
2. Off At F1-D measure voltage F1-D, 14Y 12±1.5 Go to Locate cause of low
from circuit 14Y to ground. to gnd. volts. next or no voltage in circuit
step. 14H or 14Y from
battery stud (B2), then
repair.
3. Off With fuse re-installed, (428), 63P 12±1.5 Go to Locate cause of low
disconnect connector to gnd. volts. next or no voltage in circuit
(428), and at circuit 63P step. 63P, then repair.
measure voltage to ground.
4. Off Reconnect connector (428) 64H to gnd. 12±1.5 Go to Locate cause of low
and disconnect left spot volts. next or no voltage in circuit
light at circuit 64H. At 64H step. 64P, 64E or 63H then
measure voltage to ground. repair.
5. Off Repair or replace left Go to
spotlight and switch next
assembly. step.
6. Off Disconnect right spot 64F to gnd. 12±1.5 Go to Locate cause of low
light at circuit 64F. At 64F volts. next or no voltage in circuit
measure voltage to ground. step. 63P, 64E, or 63F then
repair.

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 12 LIGHT SYSTEMS 471

Table 150 Spotlight (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
7. Off Repair or replace right Go to
spotlight and switch next
assembly. step.
8. Off Spotlight circuits check
good.

3.12. STOP, TAIL, TURN AND HAZARD SIGNAL LIGHTS WITH FLASHER
Table 151 Stop, Tail, Turn and Hazard Signal Lights With Flasher
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off Do some or all of the Go to Go to next step.
stop lights illuminate Step 8.
when the brake pedal is
depressed?
2. Off Remove fuse F3-B and F3-B. <1 ohm. Go to Locate cause of
check for open condition. next step. overload condition,
replace fuse.
3. Off At F3-B measure voltage F3-B, 14E 12±1.5 Go to Locate cause of low
from circuit 14E to to gnd. volts. next step. or no voltage in circuit
ground. 14E or 14H from battery
stud (B2), then repair.
4. Off With fuse re-installed, (640), 70 12±1.5 Go to Locate cause of low or
disconnect connector to gnd. volts next step. no voltage in circuit 70,
(640), and at circuit then repair.
70 measure voltage to
ground.
5. Off With stop light switch Across <1 ohm. Go to Replace defective stop
disconnected, measure stop light next step. light switch.
resistance across sw.
switch with brake pedal
depressed.
6. Off With stop light switch Across >100K Go to Replace defective stop
disconnected, measure stop light ohms. next step. light switch.
resistance across sw.
switch with brake pedal
released.
7. Off Disconnect connector (4), 70A 12±1.5 Go to Locate cause of low
(4), and at circuit 70A to gnd. volts. next step. or no voltage in circuit
measure voltage to 70A, then repair.
ground.

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472 12 LIGHT SYSTEMS

Table 151 Stop, Tail, Turn and Hazard Signal Lights With Flasher (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
8. Off Remove stop light (464-R10), 12±1.5 Go to Locate cause of low
relay from relay socket 70D to volts. next step. or no voltage in circuit
(464-R10), and at circuit gnd. 70D, then repair.
70D measure voltage to
ground with brake pedal
depressed.
9. Off At connector (464-R10) (464- 12±1.5 Go to Locate open or poor
measure voltage from R10), volts. next step. connection in circuit
circuit 70D to 70-G with 70D to 70-G, 56-G, 57-G, or
brake pedal depressed. 70-G. 11-G to ground stud at
right dash panel, then
repair.
10. Off Remove fuse F7-D and F7-D. <1 ohm. Go to Locate cause of
check for open condition. next step. overload condition,
replace fuse.
11. Off At F7-D measure voltage F7-D, 14F 12±1.5 Go to Locate cause of low
from circuit 14F to to gnd. volts. next step. or no voltage in circuit
ground. 14F or 14K from battery
stud (B1), then repair.
12. Off With fuse re-installed, at (464- 12±1.5 Go to Locate cause of low
relay socket (464-R10), R10). volts. next step. or no voltage in circuit
measure voltage at circuit 70E to 70E, then repair.
70E to gnd. gnd.
13. Off At relay socket Go to
(464-R10), install a test next step.
lead jumper wire between
circuits 70E and 70C.
14. Off At trailer socket (112), (112), 12±1.5 Go to Locate cause of low
measure voltage at circuit 70C to volts. next step. or no voltage in circuit
70C to ground. gnd. 70C, then repair.
15. Off Remove test jumper and (112), 12±1.5 Go to Replace defective stop
re-install stop light relay. 70C to volts. next step. light relay.
At trailer socket (112), gnd.
measure voltage at circuit
70C to ground with brake
pedal depressed.
16. Off Remove fuse F7-B and F7-B. <1 ohm. Go to Locate cause of
check for open condition. next step. overload condition,
replace fuse.
17. Off Re-install fuse F7-B. At F7-B, 14L 12±1.5 Go to Locate cause of low
F7-B measure voltage to gnd. volts. next step. or no voltage in circuit
from circuit 14L to ground. 14L or 14K from battery
stud (B1), then repair.

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 12 LIGHT SYSTEMS 473

Table 151 Stop, Tail, Turn and Hazard Signal Lights With Flasher (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
18. Off Remove relay (464-R11) (464-R11), 12±1.5 Go to Locate cause of low
and measure voltage to 56H to volts. next step. or no voltage in circuit
circuit 56H to ground. gnd. 56H, then repair.
19. Off At relay socket (464-R11), Go to
install a test lead jumper next step.
wire between circuits 56H
and 56C.
20. Off At trailer socket (112), (112), 12±1.5 Go to Locate cause of low
measure voltage at circuit 56C to volts. next step. or no voltage in circuit
56C to ground. gnd. 56C, then repair.
21. Off With test jumper still in Go to Go to next step.
place does the left turn Step 26.
indicator illuminate?
22. Off With test jumper still (422), 12±1.5 Go to Locate cause of low
in place, disconnect 56R to volts. next step. or no voltage in circuit
connector (422), and gnd. 56R or 56A, then repair.
measure voltage at circuit
56R to gnd.
23. Off With test jumper still (422) 56R 12±1.5 Go to Locate open or poor
in place, disconnect to (421) volts. next step. connection in circuit
connector at (421), and 62-GD. 62-GD or 11-GF, then
measure voltage from repair.
circuit 62-GD to 56R of
(422).
24. Off Reconnect (422) and Go to Replace defective
(421). Does left turn next step. indicator lamp.
indicator illuminate?
25. Off Remove test jumper and Go to
re-install left turn relay. next step.
26. Off Remove fuse F7-C and F7-C. <1 ohm. Go to Locate cause of
check for open condition. next step. overload condition,
replace fuse.
27. Off Re-install fuse F7-C. At F7-C, 14L 12±1.5 Go to Locate cause of low
F7-C measure voltage to gnd. volts. next step. or no voltage in circuit
from circuit 14L to ground. 14L or 14K from battery
stud (B1), then repair.
28. Off Remove relay (464-R12) (464-R12), 12±1.5 Go to Locate cause of low
and measure voltage at 57H to volts. next step. or no voltage in circuit
circuit 57H to ground. gnd. 57H, then repair.
29. Off At relay socket Go to
(464-R12), install a test next step.
lead jumper wire between
circuits 57H and 57C.

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474 12 LIGHT SYSTEMS

Table 151 Stop, Tail, Turn and Hazard Signal Lights With Flasher (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
30. Off At trailer socket (112), (112), 12±1.5 Go to Locate cause of low
measure voltage at circuit 57C to volts. next step. or no voltage in circuit
57C to ground. gnd. 57C, then repair.
31. Off With test jumper still in Go to Go to next step.
place does the right turn Step 36.
indicator illuminate?
32. Off With test jumper still (422), 12±1.5 Go to Locate cause of low
in place, disconnect 57R to volts. next step. or no voltage in circuit
connector (422), and gnd. 57R or 57A, then repair.
measure voltage at circuit
57R to gnd.
33. Off With test jumper still (422), 12±1.5 Go to Locate open or poor
in place, disconnect 57R to volts. next step. connection in circuit
connector at (421), and (421), 62-GD or 11-GF, then
measure voltage from 62-GD. repair.
circuit 62-GD to 57R of
(422).
34. Off Reconnect (422) and Go to Replace defective
(421). Does right turn next step. indicator lamp.
indicator illuminate?
35. Off Remove test jumper and Go to
re-install left turn relay. next step.
36. Off Remove fuse F2-D and F2-D <1 ohm. Go to Locate cause of
check for open condition. next step. overload condition,
replace fuse.
37. Off Re-instal fuse F2-D. At F2-D, 12±1.5 Go to Locate cause of low
F2-D measure voltage 14R to volts. next step. or no voltage in circuit
from circuit 14R to gnd. 14R or 14K from battery
ground. stud (B1), then repair.
38. Off At flasher connector Flasher 12±1.5 Go to Locate cause of low or
measure voltage from conn., 55 volts. next step. no voltage in circuit 55,
circuit 55 to ground. to gnd. then repair.
39. Off Install a test lead jumper Go to
in place of the flasher next step.
unit.
40. Off Disconnect connector (4) (4), 55A 12±1.5 Go to Locate cause of low
at turn signal pigtail, and to gnd. volts. next step. or no voltage in circuit
at circuit 55A measure 55A, then repair.
voltage to ground.

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 12 LIGHT SYSTEMS 475

Table 151 Stop, Tail, Turn and Hazard Signal Lights With Flasher (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
41. Off With connector (4) (4), BK to <1 ohm. Go to Replace defective
disconnected, move OR. next step. switch.
switch to left turn position
and measure resistance
from black wire to orange
wire.
42. Off With switch in left turn (4), BK to <1 ohm. Go to Replace defective
position, measure YL. next step. switch.
resistance from black
wire to yellow wire.
43. Off Move switch to right turn (4), BK to <1 ohm. Go to Replace defective
position and measure GN. next step. switch.
resistance from black
wire to green wire.
44. Off With switch in right (4), BK to <1 ohm. Go to Replace defective
turn position, measure BL. next step. switch.
resistance from black
wire to blue wire.
45. Off Move switch to neutral (4), RD to <1 ohm. Go to Replace defective
position and measure YL. next step. switch.
resistance from red wire
to yellow wire.
46. Off With switch in the (4), RD to <1 ohm. Go to Replace defective
neutral position, measure GN. next step. switch.
resistance from red wire
to green wire.
47. Off Remove left turn relay at (464- 12±1.5 Go to Locate cause of low
(464-R11). Reconnect R11), 56E volts. next step. or no voltage in circuit
connector (4) and move to gnd. 56E, then repair.
turn signal switch to
left turn position. At
(464-R11) measure
voltage from circuit 56E
to ground.
48. Off Re-install left turn relay. Go to Replace defective left
Move turn signal switch next step. turn relay.
to left turn position. Do
left turn lamps illuminate?
49. Off Remove right turn relay (464- 12±1.5 Go to Locate cause of low
at (464-R12). Move turn R12), volts. next step. or no voltage in circuit
signal switch to right turn 57E to 57E, then repair.
position. At (464-R12) gnd.
measure voltage from
circuit 57E to ground.

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476 12 LIGHT SYSTEMS

Table 151 Stop, Tail, Turn and Hazard Signal Lights With Flasher (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
50. Off Re-install right turn relay. Go to Replace defective right
Move turn signal switch next step. turn relay.
to right turn position.
Do right turn lamps
illuminate?
51. Off Disconnect connector (3). (3), 56B 12±1.5 Go to Locate cause of low
Move turn signal switch to gnd. volts. next step. or no voltage in circuit
to left turn position, and at 56B, then repair.
(3) measure voltage from
circuit 56B to ground.
52. Off Move turn signal switch to (3), 57B 12±1.5 Go to Locate cause of low
right turn position, and at to gnd. volts. next step. or no voltage in circuit
(3) measure voltage from 57B, then repair.
circuit 57B to ground.
53. Off Reconnect connector (127), 12±1.5 Go to Locate cause of low
(3), and disconnect 56B to volts. next step. or no voltage in circuit
connector (127). Move gnd. 56B, then repair.
turn signal switch to left
turn position, and at (127)
measure voltage from
circuit 56B to gnd.
54. Off Move turn signal switch (127), 12±1.5 Go to Locate cause of low
to right turn position, and 57B to volts. next step. or no voltage in circuit
at (127) measure voltage gnd. 57B, then repair.
from circuit 57B to gnd.
55. Off With the turn signal switch (127), 12±1.5 Go to Locate open or poor
in the right turn position, 57B to volts. next step. connection in circuit
at (127) measure voltage 11-GV. 11-GV, then repair.
from circuit 57B to 11-GV.
56. Off Reconnect connector Go to Replace defective left
(127). With turn signal next step. turn lamp or socket.
switch in left turn position,
do the left turn lamps
illuminate?
57. Off Disconnect connector (128), 12±1.5 Go to Locate cause of low
(128). Move turn signal 57B to volts. next step. or no voltage in circuit
switch to right turn gnd. 57B, then repair.
position, and at (128)
measure voltage from
circuit 57B to gnd.
58. Off With the turn signal switch (128), 12±1.5 Go to Locate open or poor
in the right turn position, 57B to volts. next step. connection in circuit
at (128) measure voltage 11-GN. 11-GN, then repair.
from circuit 57B to 11-GN.

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 12 LIGHT SYSTEMS 477

Table 151 Stop, Tail, Turn and Hazard Signal Lights With Flasher (cont.)
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
59. Off Reconnect connector Go to Replace defective right
(128). With turn signal next step. turn lamp or socket.
switch in right turn
position, do the right turn
lamps illuminate?
60. Off Remove test jumper Go to Replace defective turn
and re-install turn signal next step. signal flasher.
flasher. Do lamps flash
when turn signal switch is
moved to a turn position?
61. Off Stop, tail, turn, and
hazard signal lights
circuits check good.

3.13. WORK LIGHT WITHOUT SLEEPER

Table 152 Work Light Without Sleeper
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F2-A and F2-A. <1 ohm. Go to next Locate cause of
check for open condition. step. overload condition,
replace fuse.
2. Off Re-install fuse F2-A. At F2-A, 14T 12±1.5 Go to next Locate cause of low
F2-A measure voltage from to gnd. volts. step. or no voltage in circuit
circuit 14T to ground. 14T from battery stud
(B2), then repair.
3. Off Disconnect connector (441), 12±1.5 Go to next Locate cause of low
(441) from work light 65A to volts. step. or no voltage in circuit
switch, and at circuit 65A gnd. 65A, then repair.
measure voltage to ground.
4. Off At connector (441) (441), 12±1.5 Go to next Locate open or poor
measure voltage from 65A to volts. step. connection in circuit
circuit 65A to 65-GC. 65-GC. 65-GC or 11-GAN,
then repair.
5. Off Disconnect connector (314), <1 ohm. Go to next Locate open or poor
(314) and measure 65-GB to step. connection in circuit
resistance from circuit gnd. 65-GB or 11-GAN,
65-GB to ground. then repair.
6. Off With the switch removed Work light <1 ohm. Go to next Replace defective
and in the on position, switch step. work light switch.
measure resistance (441), 4
between terminals 4 and 5. to 5.

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478 12 LIGHT SYSTEMS

Table 152 Work Light Without Sleeper (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
7. Off With the switch removed Work light <1 ohm. Go to next Replace defective
and in the on position, switch step. work light switch.
measure resistance (441), 1
between terminals 1 and 2. to 2.
8. Off Re-install work light switch. Go to next
step.
9. Off At connector (314), with (314), 12±1.5 Go to next Locate cause of low
work light switch turned 65B to volts. step. or no voltage in circuit
on, measure voltage from gnd. 65B, then repair.
circuit 65B to gnd.
10. Off Reconnect connector Go to next Replace defective
(314). With work light step. lamp or lamp socket.
switch on, does work light
illuminate?
11. Off Does work light indicator Work light Go to next step.
lamp function when work circuits
light is switched on? check
good.
12. Off With ignition off, check fuse F4-A. <1 ohm. Go to next Locate cause of
F4-A for open condition. step. overload condition,
replace fuse.
13. On With ignition on, at F4-A F4-A, 13B 12±1.5 Go to next Locate cause of
measure voltage from to gnd. volts step. low or no voltage
circuit 13B to ground. in circuit 13B, or 13
from ignition switch,
then repair.
14. Off/On With ignition switch off, (423), 12±1.5 Go to next Locate cause of
disconnect connector 28A to volts step. low or no voltage in
(423) from work light gnd. circuit 28A, or 13V,
indicator. Turn ignition on then repair.
and measure voltage from
circuit 28A to ground.
15. Off With work light switch in (423), <1 ohm. Go to next Locate open or poor
the on position, measure 65C to step. connection in circuit
resistance at connector gnd. 65C, then repair.
(423) from circuit 65C to
gnd.
16. Off Replace defective work
lamp indicator lamp or
socket.

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 12 LIGHT SYSTEMS 479

3.14. WORK LIGHT WITH PRO SLEEPER

Table 153 Work Light With PRO SLEEPER
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F2-A and F2-A. <1 ohm. Go to next Locate cause of
check for open condition. step. overload condition,
replace fuse.
2. Off Re-install fuse F2-A, and F2-A, 12±1.5 Go to next Locate cause of low
at circuit 14T measure 14T to volts. step. or no voltage in circuit
voltage to ground. gnd. 14T from battery stud
(B2), then repair.
3. Off Disconnect connector (441), 12±1.5 Go to next Locate cause of low
(441) from work light 65A to volts. step. or no voltage in circuit
switch, and at circuit 65A gnd. 65A, then repair.
measure voltage to ground.
4. Off At connector (441) (441), 12±1.5 Go to next Locate open or poor
measure voltage from 65A to volts. step. connection in circuit
circuit 65A to 65-GC. 65-GC. 65-GC, 11-GBD, or
11-GBE, then repair.
5. Off With the switch Work <1 ohm. Go to next Replace defective
disconnected and in the light sw. step. work light switch.
on position, measure (441), 4
resistance between to 5
terminals 4 and 5.
6. Off With the switch Work <1 ohm. Go to next Replace defective
disconnected and in the light sw. step. work light switch.
on position, measure (441), 1
resistance between to 2
terminals 1 and 2.
7. Off Reconnect work light Go to next
switch. step.
8. Off With work light switch (578), 12±1.5 Go to next Locate cause of low
turned off, disconnect 65B to volts. step. or no voltage in circuit
connector (578), turn on gnd. 65B, then repair.
work light switch, and
measure voltage from
circuit 65B to ground.
9. Off With work light switch on, (578), 12±1.5 Go to next Locate open or poor
measure voltage at (578) 65B to volts. step. connection in circuit
from circuit 65B to 65-GB. 65-GB. 65-GB, or 11-GBC to
ground circuit, then
repair.

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480 12 LIGHT SYSTEMS

Table 153 Work Light With PRO SLEEPER (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
10. Off Turn off work light switch, (579), 12±1.5 Go to next Locate cause of low
disconnect connector 65F to volts. step. or no voltage in circuit
(579), turn on work light gnd. 65F, then repair.
switch, and measure
voltage from circuit 65F to
ground.
11. Off With work light switch on, (579), 12±1.5 Go to next Locate open or poor
measure voltage at (579) 65F to volts. step. connection in circuit
from circuit 65F to 65-GF. 65-GF. 65-GF, then repair.
12. Off Reconnect connector Go to next Replace defective
(578). With work light step. lamp or lamp socket.
switch on, does work light
illuminate?
13. Off Reconnect connector Go to next Replace defective
(579). With work light step. lamp or lamp socket.
switch on, does work light
illuminate?
14. Off Does work light indicator Work light Go to next step.
lamp function when work circuits
light is switched on? check
good.
15. Off With ignition off, check fuse F4-A. <1 ohm. Go to next Locate cause of
F4-A for open condition. step. overload condition,
replace fuse.
16. On With ignition on, at F4-A F4-A, 12±1.5 Go to next Locate cause of
measure voltage from 13B to volts. step. low or no voltage in
circuit 13B to ground. gnd. circuit 13B, or 13 from
ignition switch, then
repair.
17. Off/On With ignition switch off, (423), 12±1.5 Go to next Locate cause of low
disconnect connector 28A to volts. step. or no voltage in circuit
(423) from work light gnd. 28A, or 13V, then
indicator. Turn ignition on repair.
and measure voltage from
circuit 28A to ground.
18. Off With work light switch in (423), <1 ohm. Go to next Locate open or poor
the on position, measure 65C to step. connection in circuit
resistance at connector gnd. 65C, then repair.
(423) from circuit 65C to
ground.
19. Off Replace defective work
lamp indicator lamp or
socket.

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 12 LIGHT SYSTEMS 481

4. COMPONENT LOCATIONS
B1 Battery Stud.. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . . . . . Power Distribution Panel
B2 Battery Stud.. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . . . . . Power Distribution Panel
J7 Junction Point. . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . In Dash Panel Left Side
(1) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Left Side of Engine Cowl
(2) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Above Conn. 3
(3) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Below Conn. 2
(4) Turn Signal Connector. . . . .. . . . . . . .. . . . . . . .. . . . . . .. . . . . . On Steering Column
(42) Headlight Dimmer Switch. . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind/Below Lt Instrument Panel
(43) Truck Body/Trailer Feed. .. .. . .. .. .. . .. .. .. . .. .. .. . . . . . Left Back of Cab, "B" Pillar
(65) Left Fog Light. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . . . . . Left Inner Bumper
(66) Right Fog Light.. . . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . . . Right Inner Bumper
(71) Right Headlight. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . . . . . Hood Harness
(76) Horn (Inline). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Front End Harness, At Lower Left of Radiator
(77) Left Headlight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Hood Harness
(84) Left Headlight Upper Unit. . . . . . . . . . . . . . . . . . . . . . .. . . . . . Front End Harness
(85) Left Headlight Lower Unit. . . . . . . . . . . . . . . . . . . . . . .. . . . . . Front End Harness
(86) Right Headlight Upper Unit. . . . . . . . . . . . . . . . . . . . .. . . . . . Front End Harness
(87) Right Headlight Lower Unit. . . . . . . . . . . . . . . . . . . . .. . . . . . Front End Harness
(93) Sleeper Box (Inline). .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . . . . . In Left Luggage Compartment
(94) Back-Up Light Switch. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . . . . . On Transmission
(100) Left & Right Door Courtesy Light. . . . . . . . . . . . .. . . . . . Inside Door
(115) Right Cab Dome Light. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Right Roof Area
(116) Left Cab Dome Light. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Roof Area
(127) Lt Stop, Tail, Turn & Back-Up Lt. . . . . . . . . . . . . .. . . . . . Left Outer Socket
(127A) Lt Stop, Tail, Turn & Back-Up Lt.. .. . .. .. . .. .. . . . . . Left Inner Socket
(128) Rt Stop, Tail, Turn & Back-Up Lt. . . . . . . . . . . . . .. . . . . . Right Inner to Left Light Inner Socket
(148-R19 Fog Light Relay.. . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . Power Distribution Panel
(170) Turn Signal Light Left Side. . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel Left Side
(171) Turn Signal Light Right Side. . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel Right Side
(180) Front Left and Right Turn Lights. . . . . . . . . . . . . .. . . . . . Behind Turn Light Assembly
(211) Right Headlight Connector. . . . . . . . . . . . . . . . . . . .. . . . . . Crossmember Harness to Headlight
(296) Front End/Hood (Inline). . . .. . . . . . .. . . . . . .. . . . . .. . . . . . Base of Hood
(311) Right Reading Light. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Roof Near Light )
(312) Left Reading Light. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . . . Roof Near Light
(314) Work Light Inline. .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . . . . . Rear Center of Cab
(318) W/Stop, Tail & Turn (Inline). . .. . . . . . . . .. . . . . . . .. . . . . . Cab Wiring to Chassis Wiring
(420) Right Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Gauge Cluster
(421) Speedo./Tach. Gauge Cluster . .. . .. . .. . .. . .. .. . . . . . At Speedo Gauge
(422) Speedo./Tach. Module. .. . . .. . . .. . . .. . . .. . . .. . .. . . . . . Behind Speedo./Tach. Gauge
(423) Left Gauge Cluster. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Left Gauge Cluster
(425) Panel Lights Switch . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(427) Speakers. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Rear of Cab, “B” Pillar
(428) Roof Connector #2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Rt Instr. Panel/Roof Conn. to Cab Harn.
(429) Roof Connector #1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Rt Instr. Panel/Roof Conn. to Cab Harn.
(431) Windshield Wiper Motor Switch. . .. . . . . .. . . . . .. . . . . . At Switch Cluster
(432) Windshield Washer/Delay Switch. . .. .. . .. . .. .. . . . . . At Switch Cluster
(440) Fog Lights Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(441) Work Light Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(442) Dome Light Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(450) Lt Mirror Light. . . . . .. . . . . . . . . .. . . . . . . . . .. . . . . . . . .. . . . . . At Switch Cluster
(451) Rt Mirror Light.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . . . . . At Switch Cluster

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482 12 LIGHT SYSTEMS

(453) G1 Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Center of Dash Behind Wing Panel

(454) G2 Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(455) G3 Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(462) F1 Fuseblock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Fuse Panel
(462) F2 Fuseblock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Fuse Panel
(462) F3 Fuseblock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Fuse Panel
(462) F4 Fuseblock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Fuse Panel
(462–R4) Headlight Relay. . . .. . . . .. . . .. . . .. . . . .. . . .. .. . . . . . Power Distribution Panel
(463–F8) Fuseblock.. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . ... . . . . . At Fuse Panel
(463–R8) Trailer Marker Relay.. .. . .. .. .. . .. .. .. . .. ... . . . . . Power Distribution Panel
(464) F10 Fuseblock Pool. . . . . .. . . . . . . . . . . . . .. . . . . . . .. . . . . . Power Distribution Panel
(464–R9) Trailer Tail Light Relay. . . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(464–R10) Trailer Stop Light Relay . . . . .. . . . .. . . . .. .. . . . . . Power Distribution Panel
(464–R11) Left Turn Relay. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(464–R12) Right Turn Relay. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(465) Headlight Switch.. .. . .. .. .. . .. .. .. . .. .. .. . .. .. ... . . . . . At Switch Cluster
(466) Trailer Light Switch. . . . .. . . . . . . . .. . . . . . . . . .. . . . .. . . . . . At Switch Cluster
(468) DRL Park Brake Switch (USA). . . .. . . . . . . .. . . .. . . . . . Inside Center of Dash at Air Manifold
(480) Flasher-Dualtec. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. ... . . . . . Right Side of Power Distrib. Center/Fuse Panel
(494) I1 Ignition Adapter. .. . . . .. . . . .. . . . .. . . . .. . . . .. . .. . . . . . Behind Fuse Panel
(495) I2 Ignition Adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel
(497) (B1) Battery Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel
(498) (B2) Battery Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel
(499) A1 Accessory Adapter. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel Right Side
(501) A3 Accessory Adapter. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel Right Side, Overlay
(503) L1 Panel Light Feed Adapter. .. . .. . .. . .. . .. . ... . . . . . Behind Instrument Panel
(506) L4 Panel Lights Ground Adapter. . . . . . . . . . . . .. . . . . . Behind Instrument Panel/Switch Breakout
(513) DRL Module - USA. .. . . . .. . . . .. . . . .. . . . .. . . . .. .. . . . . . Inside Center of Dash Strapped to Cab Harness
(520) Clearance Light. .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. .. . . . . . At Clearance Light Pigtail (Inline)
(521) Clearance Light. .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. .. . . . . . At Clearance Light Pigtail (Inline)
(522) Clearance Light. .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. .. . . . . . At Clearance Light Pigtail (Inline)
(523) Clearance Light. .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. .. . . . . . At Clearance Light Pigtail (Inline)
(524) Clearance Light. .. . . .. . .. . . .. . . .. . .. . . .. . . .. . .. .. . . . . . At Clearance Light Pigtail (Inline)
(560) Gauge Panel Light. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Instrument Cluster
(578) Left Work Light W/PRO SLEEPER. . . . . . . . . . .. . . . . . At Light Pigtail (Inline)
(579) Right Work Light W/PRO SLEEPER. . . . . . . . .. . . . . . At Light Pigtail (Inline)
(640) Stop Light Switch. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . .. . . . . . Dash Panel, Left Side, Engine Compartment
(922) Trailer Socket Connector #1. . . . . . . . . . . . . . . . . .. . . . . . Left Back of Cab, “B” Pillar
(923) Trailer Socket Connector #2. . . . . . . . . . . . . . . . . .. . . . . . Left Back of Cab, “B” Pillar
(925) Trailer Socket Connector #1. . . . . . . . . . . . . . . . . .. . . . . . Left Back of Cab, “B” Pillar
(926) Trailer Socket Connector #2. . . . . . . . . . . . . . . . . .. . . . . . Left Back of Cab, “B” Pillar
(935) Work Light Connector. .. . . .. . . . .. . . .. . . .. . . . .. .. . . . . . Left Rear of Cab, “B” Pillar

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Figure 137 Stop, Tail And Turn Light Wiring 9100i, 9200i, 9400i And 9900i
NOTE: CONNECTOR NUMBERS SHOWN IN PARENTHESES
1. 22-WAY DASH CONNECTOR (3)
2. CHASSIS HARNESS
3. WIRING TO REAR OF VEHICLE

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Figure 138 Stop, Tail And Turn Light Wiring 9400i And 9900i, No Chassis Skirts
1. WIRING TO REAR OF VEHICLE
2. WIRING TO FRONT OF VEHICLE

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Figure 139 Stop, Tail And Turn Light Wiring 9100i, 9200i, 9400i And 9900i
1. WIRING TO FRONT OF VEHICLE
2. WIRING TO REAR OF VEHICLE

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486 12 LIGHT SYSTEMS

Figure 140 Stop, Tail And Turn Light Wiring 9100i, 9200i, 9400i, And 9900i
1. STOP AND TAIL LIGHT HARNESS
2. RIGHT TAIL LIGHT (128)
3. LEFT TAIL LIGHT (127), (127A) INSIDE
4. CHASSIS HARNESS—STOP, TAIL AND TURN LIGHT WIRING HARNESS

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 12 LIGHT SYSTEMS 487

Figure 141 Relays, Fuses And Circuit Breakers 9100, 9200, 9400 And 9900
1. (B1) BATTERY STUD
2. (B2) BATTERY STUD
3. (148) FOG LIGHT RELAY
4. TURN SIGNAL FLASHER
5. OPTIONAL ALARM

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Figure 142 Fixed Steering Column Wiring 9100i, 9200i, 9400i And 9900i
1. HORN BUTTON ASSEMBLY
2. TURN SIGNAL SWITCH
3. GROUND
4. CONDUIT, CONVULATED TUBING
5. GROUND
6. TURN SIGNAL 6-WAY CONNECTOR (4)
7. MAIN CAB HARNESS

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Figure 143 Tilt-Telescope Steering Column Wiring 9100i, 9200i, 9400i and 9900i
1. TURN SIGNAL SWITCH
2. CIRCUIT 85C
3. TURN SIGNAL 6-WAY CONNECTOR (4)
4. MAIN CAB HARNESS
5. HORN CIRCUIT 85C

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Figure 144 Switch Panel Wiring

1. PANEL LIGHT DIMMER SWITCH (425)
2. HEADLIGHT SWITCH (465)
3. CAB AND TRAILER LIGHTS SWITCH (466)
4. MAIN CAB HARNESS

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Figure 145 Cab Wiring, Non-PRO SLEEPER

1. VAN BODY CONNECTOR (43)
2. WORK LIGHT CONNECTOR (935)
3. TRAILER SOCKET CONNECTORS (922) & (923)
4. TRAILER SOCKET GROUND CONNECTOR
5. RADIO SPEAKER CONNECTOR (427)
6. HEADLIGHT DIMMER SWITCH (42)
7. DASH CONNECTOR (1)
8. TO GROUND STUD
9. MAIN CAB HARNESS

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Figure 146 Cab, Roof Harness Wiring

1. CAB ROOF HARNESS TO ROOF WIRING
2. MAIN CAB HARNESS

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Figure 147 Cab, Clearance, Identification, Dome And Reading Lights (Day Cab without Sun Shade)
1. ROOF CONNECTOR (429)
2. RIGHT READING LAMP (311)
3. DOME LIGHT LEFT (116) & RIGHT (115)
4. LEFT READING LAMP (312)
5. IDENTIFICATION AND CLEARANCE LAMPS
6. CAB ROOF HARNESS

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Figure 148 Cab, Clearance, Identification, Dome And Reading Lights (Day Cab with Sun Shade)
1. RIGHT READING LAMP (311)
2. DOME LIGHT LEFT (116) & RIGHT (115)
3. LEFT READING LAMP (312)
4. CLEARANCE LIGHT CONNECTOR (345)
5. CAB ROOF HARNESS
6. IDENTIFICATION AND CLEARANCE LAMPS

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Figure 149 Cab, Clearance, Identification, Dome And Reading Lights (With Low And High Roof Pro
Sleepers)
1. ROOF CONNECTOR (429)
2. RIGHT READING LAMP (311)
3. DOME LIGHT LEFT (116) & RIGHT (115)
4. LEFT READING LAMP (312)
5. CLEARANCE LIGHT CONNECTOR (345)
6. CAB ROOF HARNESS
7. IDENTIFICATION AND CLEARANCE LAMPS

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496 12 LIGHT SYSTEMS

Figure 150 Cab, Clearance, Identification, Dome And Reading Lights (With Sky Rise Pro Sleepers)
1. RIGHT READING LAMP (311)
2. DOME LIGHT RIGHT (115)
3. LEFT READING LAMP (312)
4. DOME LIGHT LEFT (116)
5. CAB ROOF HARNESS
6. IDENTIFICATION AND CLEARANCE LAMPS

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Figure 151 Door Courtesy Light Wiring

1. RIGHT DOOR WIRING HARNESS
2. LEFT DOOR WIRING HARNESS
3. COURTESY LIGHT AND MIRROR CONNECTOR (1050)
4. COURTESY LIGHT AND MIRROR CONNECTOR (1054)

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Figure 152 Door Courtesy Light Wiring (Left Door Shown)

1. COURTESY LIGHT AND MIRROR CONNECTOR (1050), (1054) FOR RIGHT SIDE
2. COURTESY LIGHT
3. COURTESY LIGHT CONNECTOR (1125), (1126) FOR RIGHT SIDE
4. DOOR SWITCH (1052), (1051) FOR RIGHT SIDE

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Figure 153 Daytime Running Light (DRL) Cab Wiring

1. AIR LINE
2. PARKING BRAKE SWITCH (468)
3. INSTRUMENT/CAB HARNESS
4. ELECTRONIC DRL MODULE (513)

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500 12 LIGHT SYSTEMS

Figure 154 Headlight Wiring

1. BRAKE SWITCH (141)
2. STOP LIGHT SWITCH (640)
3. J7 GROUND STUD
4. CONNECTOR (1)
5. FRONT END HARNESS

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Figure 155 Headlight Wiring

1. FRONT END HARNESS
2. TO DASH PANEL
3. TO HEADLIGHTS

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502 12 LIGHT SYSTEMS

Figure 156 Headlight Wiring

1. FRONT END HARNESS TO RIGHT HEADLIGHT
2. HORN CONNECTOR (76)
3. FRONT END HARNESS TO DASH PANEL
4. CIRCUIT 11-GR TO RADIATOR GROUND
5. TO LEFT HEADLIGHT

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Figure 157 Headlight Wiring

1. LEFT HEADLIGHT
2. FRONT CROSSMEMBER
3. HOOD HARNESS
4. RIGHT HEADLIGHT
5. CONNECTOR (211)
6. FOGLIGHT CONNECTOR (66)
7. FOGLIGHT CONNECTOR (65)
8. CONNECTOR (296)

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504 12 LIGHT SYSTEMS

Figure 158 Foglight Wiring (Typical)

1. BUMPER RE-INFORCEMENT
2. CIRCUITS 64C & 64-GA
3. FRONT END HARNESS
4. CIRCUITS 64D & 64-GB

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Figure 159 Spotlight Wiring (Typical)

1. CIRCUIT 64F TO RIGHT SPOTLIGHT
2. CIRCUIT 64F TO 64D
3. CIRCUIT 64F TO 64E
4. LEFT SPOTLIGHT
5. CIRCUIT 64H

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Figure 160 Work Lights, Without Sleeper

1. WORK LIGHT SWITCH
2. CAB HARNESS
3. CIRCUITS 65A & 65C (935)
4.CIRCUIT 11-GAN
5. WORK LIGHT HARNESS
6. WORK LIGHT CONNECTOR (314)
7. WORK LIGHT

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Figure 161 Work Lights, Pro Sleeper

1. RIGHT WORK LIGHT
2. RIGHT WORK LIGHT CONNECTOR (579)
3. LEFT WORK LIGHT CONNECTOR (578)
4. LEFT WORK LIGHT
5. SLEEPER GROUND STUD
6. WORK LIGHT CONNECTOR (935)
7. WORK LIGHT SWITCH (441)

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508 12 LIGHT SYSTEMS

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 13 SLEEPER LIGHTING AND ACCESSORIES 509

Table of Contents

1. DESCRIPTION. . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . ..511
1.1. AUXILIARY CIRCULATION FAN (LOW ROOF, HIGH ROOF & SKYRISE). . . . . . . . . . . . . . . . . . . . . .511
1.2. AUXILIARY RADIO CONTROLS.. .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. .. . .. .. .. .. ..511
1.3. BUNK FLUORESCENT AND READING LIGHTS . .. . .. . . . . . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . . .. . ..511
1.4. BUNK SPEAKERS .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .. . .. . .. . .. . .. . ..511
1.5. LUGGAGE COMPARTMENT LIGHTS .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. .. . .. .. .. . .. .. .. .. . .. .. .. . .. .. ..511
1.6. POWER SALEM VENT . . . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. . . .. . .. . . .. . .. . . .. . . ..511
1.7. POWER SOURCE (SLEEPER) . . . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . . ..511
1.8. REFRIGERATOR WIRING . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . .. . . . . .. . . . . . .. . . . . .. . .511
1.9. TV/VCR WIRING . .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. ..511
1.10. OVERHEAD CABINETS, ACCENT LIGHTS WIRING . . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. .. . .. ..511

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .512
2.1. AUXILIARY CIRCULATION FAN (LOW ROOF, HIGH ROOF & SKYRISE) . .. .. .. . .. .. .. . .. .. .. .512
2.2. AUXILIARY RADIO CONTROLS .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .512
2.3. BUNK FLUORESCENT AND READING LIGHTS .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .512
2.4. BUNK SPEAKERS. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .512
2.5. LUGGAGE COMPARTMENT LIGHTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .512
2.6. POWER SALEM VENT . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .513
2.7. POWER SOURCE (SLEEPER) . . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .513
2.8. REFRIGERATOR WIRING . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . .513
2.9. TV/VCR WIRING. . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .513
2.10. OVERHEAD CABINETS, ACCENT LIGHTS. .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .513

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .513
3.1. AUXILIARY CIRCULATION FAN (LOW ROOF, HIGH ROOF & SKYRISE). . . . . . . . . . . . . . . . . . . . . .514
3.2. AUXILIARY RADIO CONTROLS .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .515
3.3. BUNK FLUORESCENT AND READING LIGHTS .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .516
3.4. BUNK SPEAKERS . . .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .520
3.5. LUGGAGE COMPARTMENT LIGHTS. . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . .522
3.6. POWER SALEM VENT . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .524
3.7. POWER SOURCE (SLEEPER). .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .525
3.8. REFRIGERATOR WIRING.. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . . .. . .. . .. . .. . .. . .. . .. . .. . .. . .526
3.9. TV/VCR WIRING. . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .. . . .. . . .. . . .. . .528
3.10. OVERHEAD CABINETS, ACCENT LIGHTS WIRING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .529

4. COMPONENT LOCATIONS. .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .531

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 13 SLEEPER LIGHTING AND ACCESSORIES 511

1. DESCRIPTION
1.1. AUXILIARY CIRCULATION FAN (LOW ROOF, HIGH ROOF & SKYRISE)
The auxiliary circulation fan is a small fan that is located in the PRO SLEEPER (LOW ROOF, HIGH ROOF &
SKYRISE) to provide a means of circulating the air. It has two speeds of operation.

1.2. AUXILIARY RADIO CONTROLS

The auxiliary radio controls are a set of switches that allow the radio band (AM/FM) and station to be changed
from the PRO SLEEPER bunk.

1.3. BUNK FLUORESCENT AND READING LIGHTS

The bunk fluorescent light assembly is designed to provide the main source of illumination in the sleeper. Two
additional switches are provided, one in the bunk control panel and one in the dash panel. A reading light is
located in each of the two sleeper bunks to provide illumination for reading when the fluorescent lamp is turned
off, or when additional light is needed.

1.4. BUNK SPEAKERS

A standard volume/balance control for the radio provides control of the bunk speakers in the PRO SLEEPER.

1.5. LUGGAGE COMPARTMENT LIGHTS

Two luggage compartment lights are available on sleeper models, one on the left side and one on the right
side. A switch is provided on each light.

1.6. POWER SALEM VENT

A power Salem vent is provided to draw air out of the PRO SLEEPER, thus allowing fresh air to enter the
sleeper.

1.7. POWER SOURCE (SLEEPER)

A power source (power socket) is provided to enable 12 volt accessories to be plugged in. The socket is
located near the base of the bunk coming out of the right luggage compartment behind the passenger seat.

1.8. REFRIGERATOR WIRING

A power socket and on/off switch is provided to power a refrigerator with the PRO SLEEPER. This power
feed is connected to the (B2) battery stud.

1.9. TV/VCR WIRING

A power socket is provided to enable a 12 volt TV, 12 volt VCR or “Y” adapter to be plugged in. An on/off
switch is provided for the power socket.

1.10. OVERHEAD CABINETS, ACCENT LIGHTS WIRING

The overhead cabinets right, center and left accent lights are controlled by the accent lights on/off switch in the
High Roof and EAGLE PRO SLEEPERS.

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512 13 SLEEPER LIGHTING AND ACCESSORIES

2. OPERATION
Refer to the SLEEPER LIGHTING AND ACCESSORIES circuit diagrams in CTS-5298 or S08225.

2.1. AUXILIARY CIRCULATION FAN (LOW ROOF, HIGH ROOF & SKYRISE)
When the auxiliary circulation fan is switched to high or low position, power flows from the (B2) battery stud
through circuits 14AK, 14AV, 30A fuse F10–D, and circuit 14AX to 5A fuse 582–B. From there power flows
through circuits 76L and 76K to the fan switch and fan motor. The ground path consists of circuits 76–GK,
76–GL, 11–GAC, 11–GAD, 11–GAG, 11–GBC, 11–GBD to ground adapter (454).

2.2. AUXILIARY RADIO CONTROLS

The radio station is changed in the up direction when the seek switch is closed and current flows through circuit
86H, seek switch, and circuit 86J. The radio station selection is changed in the down direction when the seek
switch is closed and current flows through circuit 86K, seek switch and circuit 86J. The radio band is changed
when the band switch is closed and current flows through circuit 86L, the band switch, and circuit 86M.

2.3. BUNK FLUORESCENT AND READING LIGHTS

When the bunk dome light switch is moved at either of the two locations or the sleeper dome light switch is
moved, current will flow from battery stud (B2), through circuits 14AK, 14AP, 20A fuse F8 – D, circuits 63AA,
and 63AP to the bunk fluorescent light. The ground circuit is 63–GJ or 63–GK between the two bunk dome
light switches, and circuit 63–GE or 63–GF going to the sleeper dome light switch, and circuits 63–GA, 62–GE,
11–GAB, and 11–GB to ground stud at right dash panel.

When the lower bunk reading light switch is turned on, current will flow from battery stud (B2), through circuit
14AK, 14AP, fuse F8 – D, circuits 63AA, and 63AP, 63AS and 63W to the reading light switch and lamp. The
ground circuit is 63–GW, 11–GAD and 11–GBD to ground adapter (454).

When the upper bunk reading light switch is turned on, current will flow from battery stud (B2), through
circuits 14AK, 14AP, fuse F8–D, circuits 63AA, 63AP, 63AS and 63U to the reading light switch and lamp.
The ground circuit is 63–GU, (switch [220] and circuit 63GX with the Sky-Rise) 11–GAD and 11–GBD to
ground adapter (454).

In the Sky-Rise model switch (220) is opened when the upper bunk is raised. This will inhibit the upper bunk
reading light from illuminating.

When the under cabinet light switch is turned on, current will flow from battery stud (B2) through circuits 14AK,
14AP, fuse F8 – D, circuit 63AA, 63AP, 63AS and 63AR to the under cabinet light switch and lamp. The ground
circuit is 63–GR, 11–GAD and 11–GBD to ground adapter (454).

2.4. BUNK SPEAKERS

Audio power is fed to the left bunk speaker volume/balance control on circuits 86AR and 86AS. Audio power is
fed to the right bunk speaker volume/balance control on circuits 86AU and 86AT. Audio power is then fed to
the left bunk speaker on circuits 86AW and 86AX. Audio power is fed to the right bunk speaker on circuits
86AY and 86AZ.

2.5. LUGGAGE COMPARTMENT LIGHTS

When the left luggage compartment switch is closed, power flows from battery stud (B2) through circuits
14AK, 14AP, fuse F8 – D, circuits 63AA, 63AB, and 63AJ to the left luggage compartment light switch. Then

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 13 SLEEPER LIGHTING AND ACCESSORIES 513

power flows through circuits 63AK, and 63AL to the left lamp. If the right luggage compartment light switch is
closed, power will also flow through 63AB, but additionally it will flow through circuit 63AD to the right luggage
compartment light switch. Then power flows through circuit 63AE to the right lamp. The ground path for the left
light is circuits 63–GAK, 11–GAF, 11–GBC, 11–GBD and 11–GBE to ground adapter (454). The ground path
for the right light is circuits 63–GD, 11–GAG, 11–GBC, 11–GBD and 11–GBE to ground adapter (454).

2.6. POWER SALEM VENT

With the vent switch in the low or high position, power flows from battery stud (B2) through circuit 14AK, 14AV,
fuse F10–B, circuit 14AX, fuse 582 – B, circuit 76K and 76M to the Power Salem Vent. The ground path is
circuit 76–GM, 11–GAF, 11–GBC, 11–GBD, and 11–GBE to ground adapter (454).

2.7. POWER SOURCE (SLEEPER)

If an accessory is plugged into the right auxiliary power source sockets power will flow from battery stud (B2)
through circuits 14AK, 14AW, fuse F10–C and circuit 14AY to right auxiliary power source socket. The ground
path is circuits 11-GAG, 11-GBC, and 11-GBD and 11-GBC to ground adapter (454).

2.8. REFRIGERATOR WIRING

With the refrigerator on/off switch in the on position, power flows from battery stud (B2) through circuits 14AK,
14AV, fuse F10–B, circuit 14AX, fuse 582–C, circuit 86AV, refrigerator on/off switch, and circuit 86AG to the
refrigerator power source. The ground path is circuits 86–GR, 11–GBD and 11–GBC to ground adapter (454).
When the ignition is turned on, power energizes the auxiliary bunk blower relay which makes available power
to circuits 62BP and 62X going to refrigerator on/off switch. This illuminates the panel lamp LED through
ground path 62–GX, 86–GK, 11–GAF, 11–GBC, 11–GBD, and 11–GBC to ground adapter (454). When the
refrigerator on/off switch is turned on, the on indicator LED will illuminate through ground path 62–GX, 86–GK,
11–GAF, 11–GBC, 11–GBD and 11–GBC to ground adapter (454).

2.9. TV/VCR WIRING

With the TV/VCR on/off switch in the on position, power flows from battery stud (B2) through circuits 14AK,
14AV, fuse F10–D, circuit 14AX, fuse 582–A, circuit 86X and TV/VCR on/off switch. From the switch power
flows through circuits 86Y and 86AR to the TV power source socket. The ground path is circuits 86–GP,
11–GAC, 11–GAD, 11–GBD and 11–GBC to ground adapter (454). When the ignition is turned on, power
energizes the auxiliary bunk blower relay which makes available power to circuits 62BP and 62Y going to
TV/VCR on/off switch. This illuminates the panel lamp LED through ground path 62–GY, 11–GAF, 11–GBC,
11–GBD and 11–GBC to ground adapter (454).

2.10. OVERHEAD CABINETS, ACCENT LIGHTS

With the TV/VCR on/off switch in the on position, power flows from battery stud (B2) through circuits 14AK,
14AV, fuse F10–D, circuit 14AX, fuse 582–A, circuit 86X and TV/VCR on/off switch. From the switch power
flows through circuits 86Y and 86AR to the TV power source socket. The ground path is circuits 86–GP,
11–GAC, 11–GAD, 11–GBD and 11–GBC to ground adapter (454). When the ignition is turned on, power
energizes the auxiliary bunk blower relay which makes available power to circuits 62BP and 62Y going to
TV/VCR on/off switch. This illuminates the panel lamp LED through ground path 62–GY, 11–GAF, 11–GBC,
11–GBD and 11–GBC to ground adapter (454).

3. TROUBLESHOOTING
Refer to the SLEEPER LIGHTING AND ACCESSORIES circuit diagrams in CTS-5298 or S08225.

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A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 12.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 –
ELECTRICAL in the CTS – 5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not
covered in detail. It is assumed that the technician knows to check for a malfunctioning switch,
relay, or solenoid.

3.1. AUXILIARY CIRCULATION FAN (LOW ROOF, HIGH ROOF & SKYRISE)
Table 154 Auxiliary Circulation Fan (LOW ROOF, HIGH ROOF & SKYRISE)
STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F10–D and F10–D. <1 ohm. Go to Locate cause of
check for open condition. next step. overload condition,
then repair. Replace
fuse.
2. Off Re-install fuse F10-D and F10 – D, 12 ± 1.5 Go to Locate cause of low
measure voltage at circuit 14AV to volts. next step. or no voltage in circuit
14AV to ground. gnd. 14AK or 14AV from
battery stud (B2), then
repair.
3. Off Remove fuse 582-B and 582-B. <1 ohm. Go to Locate cause of
check for open condition. next step. overload condition,
then repair. Replace
fuse.
4. Off Re-install fuse 582-B and 582-B, 12 ± 1.5 Go to Locate cause of low
measure voltage at circuit 14AX to volts. next step. or no voltage in circuit
14AX to ground. gnd. 14AX from fuse F10 –
D, then repair.
5. Off Disconnect connector (611) (611) or 12 ± 1.5 Go to Locate cause of low
or (1305) and measure (1305), volts. next step. or no voltage in circuit
voltage from circuit 76K or 76K to 76K or 76L from fuse
76L to ground. gnd. 582-B, then repair.

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Table 154 Auxiliary Circulation Fan (LOW ROOF, HIGH ROOF & SKYRISE) (cont.)
STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
6. Off At connector (611) or (611) or 12 ± 1.5 Go to Locate open or
(1305), measure voltage (1305), volts. next step. poor connection in
from circuit 76K or 76L to 76K to circuit 76-GK or 76L,
76 – GK or 76 – GL. 76-GK or 11-GAG, 11-GAD,
76 – GL. 11-GBC or 11-GBD to
gnd. adapter (454),
then repair.
7. Off Circuits to fan check good. Fan and Repair or replace
Reconnect connector (611) circuits defective fan
or (1305). Does fan run in check assembly.
low and high position? good.

3.2. AUXILIARY RADIO CONTROLS

Table 155 Auxiliary Radio Controls
STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
1. Off Disconnect connector (483), > 100K Go to next Replace defective
(483). With station seek 86H to ohms. step. station seek up –
up – down switch in 86J. down switch.
neutral position, measure
resistance from circuit 86H
to 86J.
2. Off With station seek up – (483), <1 ohm. Go to next Locate open or poor
down switch in up position, 86H to step. connection in circuit
measure resistance from 86J. 86H, 86J or station
circuit 86H to 86J. seek up-down switch.
Repair circuit or
replace defective
station seek up-down
switch.
3. Off With station seek up – (483), > 100K Go to next Replace defective
down switch in neutral 86K to ohms. step. station seek up –
position, measure 86J. down switch.
resistance from circuit
86K to 86J.
4. Off With station seek up – (483), <1 ohm. Go to next Locate open or poor
down switch in down 86K to step. connection in circuit
position, measure 86J. 86J, 86K or station
resistance from circuit seek up-down switch.
86K to 86J. Repair circuit or
replace defective
station seek up-down
switch.

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Table 155 Auxiliary Radio Controls (cont.)

STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
5. Off Disconnect connector (474), > 100K Go to next Replace defective
(474). Measure resistance 86L to ohms. step. station seek up –
from circuit 86L to 86M. 86M. down switch.
6. Off With band switch in the (474), <1 ohm. Go to next Locate open or poor
closed position, measure 86L to step. connection in circuit
resistance from circuit 86L 86M 86L, 86M or band
to 86M. select switch. Repair
circuit or replace
defective band switch.
7. Off Auxiliary radio control
circuits check good.

3.3. BUNK FLUORESCENT AND READING LIGHTS

Table 156 Bunk Fluorescent and Reading Lights
STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F8-D and F8-D. <1 ohm. Go to next Locate cause of
check for open position. step. overload condition,
then repair. Replace
fuse.
2. Off Re-install fuse F8-D and F8-D 12 ± 1.5 Go to next Locate cause of low
measure voltage at circuit 14AP to volts. step. or no voltage in circuit
14AP to ground. gnd. 14AP from battery stud
(B2), then repair.
3. Off Does the bunk Go to Step Go to next step.
fluorescent light 24.
illuminate?
4. Off Disconnect connector (603), 12 ± 1.5 Go to next Locate cause of low
(603) and measure 63AP to volts. step. or no voltage in circuit
voltage from circuit 63AP gnd. 63AP or 63AA from
to ground. fuse F8-D, then repair.
5. Off Disconnect connector (502), <1 ohm. Go to next Locate open or
(502) from sleeper dome 63-GA to step. poor connection in
light switch, and measure gnd. circuit 62-GE, 63-GA,
resistance from 63-GA to 11-GAB, or 11-GB to
gnd. gnd., then repair.
6. Off Measure resistance of Sleeper <1 ohm Go to next Replace defective
sleeper dome light switch dome in one step. switch.
from terminal 2 to 1 in light position,
both positions. switch, 2 >100K
to 1. ohms in
other.

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Table 156 Bunk Fluorescent and Reading Lights (cont.)

STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
7. Off Measure resistance of Sleeper <1 ohm Go to next Replace defective
sleeper dome light switch dome in one step. switch.
from terminal 2 to 3 in light position,
both positions. switch, 2 >100K
to 3. ohms in
other.
8. Off Does the sleeper dome Go to Step Go to next step.
light switch panel lamp 13.
illuminate when the
headlights are turned on?
9. Off With headlights turned (502), 12 ± 1.5 Go to next Locate cause of low or
on, at connector (502) 62E to volts. step. no voltage in circuits
measure voltage from gnd. 62E, 62AP or 62M
circuit 62E to ground. coming from panel light
switch, then repair.
10. Off With headlights still on, (502), 12 ± 1.5 Go to next Locate open or poor
at (502) measure voltage 62E to volts. step. connection in circuit
from circuit 62E to 62-GE. 62-GE. 62-GE, then repair.
11. Off Circuit for panel lamp Go to next
checks good, replace step.
sleeper dome light switch.
12. Off Re-install connector (594), <1 ohm Go to next Locate open or poor
(502), and disconnect 63-GE to in one step. connection in circuit
connector (594) from gnd. position, 63-GE, then repair.
bunk dome light switch. >100K
Measure resistance from ohms in
63-GE to gnd. with other.
sleeper dome light switch
in both positions.
13. Off Measure resistance from (594). <1 ohm Go to next Locate open or poor
63-GF to gnd. with 63-GF to in one step. connection in circuit
sleeper dome light switch gnd. position, 63-GF, then repair.
in both positions. >100K
ohms in
other.
14. Off Measure resistance of Switch <1 ohm Go to next Replace defective
bunk dome light switch (594), 1 in one step. switch.
(594) from terminal 1 to 2 and 4 position,
to 2, and 4 to 5 in both to 5. >100K
positions. ohms in
other.

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Table 156 Bunk Fluorescent and Reading Lights (cont.)

STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
15. Off Measure resistance of Switch <1 ohm Go to next Replace defective
bunk dome light switch (594), 3 in one step. switch.
(594) from terminal 3 to 2 and 6 position,
to 2, and 6 to 5 in both to 5. >100K
positions. ohms in
other.
16. Off Does the bunk dome Go to Step Go to next step.
light switch panel 20.
lamp illuminate when
headlights are turned on?
17. Off With headlights turned (594), 12 ± 1.5 Go to next Locate cause of low
on, at connector (594) 62Z to volts. step. or no voltage in circuit
measure voltage from gnd. 62BP or 62Z coming
circuit 62Z to gnd. from auxiliary bunk
blower relay, then
repair.
18. Off With headlights still on, (594), 12 ± 1.5 Go to next Locate open or poor
at (594) measure voltage 62Z to volts. step. connection in circuit
from circuit 62Z to 62-GZ. 62-GZ. 62-GZ, 11-GAE,
11-GAF, 11-GM,
11-GBC or 11-GBD
or to gnd. adapter
(454), then repair.
19. Off Circuit for panel lamp Go to next
checks good; replace step.
bunk dome light switch.
20. Off Reconnect connector (603), <1 ohm Go to next Locate open or poor
(594), and at connector 63-GJ to in one step. connection in circuit
(603) measure resistance gnd. position, 63-GJ, then repair.
to ground at circuit 63-GJ >100K
with bunk dome light ohms in
switch in both positions. other.
21. Off At connector (603) (603), <1 ohm Go to next Locate open or poor
measure resistance to white wire in one step. connection in circuit
ground at white wire with to gnd. position, 63-GK, then repair.
bunk dome light switch in >100K
both positions. ohms in
other.
22. Off At connector (603) (603), <1 ohm Go to next Locate open or poor
measure resistance to black wire in one step. connection in black
ground at black wire with to gnd. position, wire or circuit 63-GJ,
bunk dome light switch in >100K then repair.
both positions. ohms in
other.

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Table 156 Bunk Fluorescent and Reading Lights (cont.)

STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
23. Off Repair or replace Go to next
defective bunk step.
fluorescent light
switch/lamp/socket
assembly.
24. Off Does the under cabinet Go to Step Go to next step.
light illuminate when the 28.
switch is turned on?
25. Off Disconnect connector (605), 12 ± 1.5 Go to next Locate cause of low or
(605) and measure 63AR to volts. step. no voltage in circuits
voltage from circuit 63AR gnd. 63AR, 63AS, then
to gnd. repair.
26. Off At connector (605) (605), 12 ± 1.5 Go to next Locate open or poor
measure voltage from 63AR to volts. step. connection in circuits
circuit 63AR to 63-GR. 63-GR. 63-GR, or 11-GAD,
then repair.
27. Off Repair or replace Go to next
defective under cabinet step.
light switch/ lamp/socket
assembly.
28. Off Does the lower bunk Go to Step Go to next step.
reading light illuminate 32.
when the switch is turned
on?
29. Off Disconnect connector (720), 12 ± 1.5 Go to next Locate cause of low or
(720) and measure 63W to volts. step. no voltage in circuits
voltage from circuit 63W gnd. 63AS, 63W, then repair.
to gnd.
30. Off At connector (720) (720), 12 ± 1.5 Go to next Locate open or poor
measure voltage from 63W to volts. step. connection in circuits
circuit 63W to 63-GW. 63-GW. 63-GW or 11-GAD,
then repair.
31. Off Repair or replace Go to next
defective reading light step.
switch/ lamp/ socket
assembly.
32. Off Does the upper bunk Go to Step Go to next step
reading light illuminate 40.
when the bunk is lowered
and the switch is turned
on?

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Table 156 Bunk Fluorescent and Reading Lights (cont.)

STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
33. Off Disconnect conn. (604) (604), 12 ±1.5 Go to next Locate cause of low or
and measure voltage 63U to volts. step. no voltage in circuits
from circuit 63U to gnd. 63AS, 63U, then repair.
ground.
34. Off At connector (604) (604), 12 ± 1.5 Go to next Locate open or poor
measure voltage from 63U to volts. step. connection in circuit
circuit 63U to 63-GU. 63-GU. 63-GU or 11-GAD, then
repair.
35. Off Does this model Go to next Go to Step 39.
(Sky-Rise) have upper step.
bunk reading light gnd.
switch (220)?
36. Off Disconnect conn. (220) (220), 12 ± 1.5 Go to next Locate cause of low
and measure voltage 63-GU to volts. step or no voltage in circuit
from circuit 63-GU to gnd. 63-GU, then repair.
ground.
37. Off At conn. (220) measure (220), 12 ± 1.5 Go to next Locate open or poor
voltage from circuit 63-GU to volts. step. connection in circuit
63-GU to 63-GX. 63-GX. 63-GX or 11-GAD, then
repair.
38. Off Repair or replace Go to Step
defective switch (220). 40.
39. Off Repair or replace Go to next
defective reading light step.
switch/ lamp/ socket
assembly.
40. Off Bunk fluorescent and
reading light circuits
check good.

3.4. BUNK SPEAKERS

Table 157 Bunk Speakers
STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF
POINTS SPEC. SPEC.
1. Off Disconnect conn. (574) Across left 3.5 to 4.5 Go to Replace defective
and measure resistance of speaker. ohms. next speaker.
left speaker. step.
2. Off Disconnect conn. (117), (117), 86AW 3.5 to 4.5 Go to Locate short
and reconnect conn. to 86AX. ohms. next or open circuit
(574). At (117) measure step. condition in circuit
resistance across circuits 86AW or 86AX,
86AW and 86AX. then repair.

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Table 157 Bunk Speakers (cont.)

STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF
POINTS SPEC. SPEC.
3. Off Disconnect conn. (575) Across right 3.5 to 4.5 Go to Replace defective
and measure resistance of speaker. ohms. next speaker.
right speaker. step.
4. Off Disconnect connector (118), 86AY 3.5 to 4.5 Go to Locate short
(118), and reconnect to 86AZ. ohms. next or open circuit
connector (575). At (118) step. condition in circuit
measure resistance across 86AY or 86AZ,
circuits 86AY and 86AZ. then repair.
5. Off At conn. (117), on the (117), YL to 45 to 55 Go to Repair or replace
volume/balance control GN. ohms. next defective volume
connector half side, step. control.
measure resistance across
yellow wire and green wire
that connects up with the
green wire that runs to
connector (427).
6. Off At conn. (118), on the (118), BN to 45 to 55 Go to Repair or replace
volume/balance control RD. ohms. next defective volume
connector half side, step. control.
measure resistance across
brown wire and red wire
that connects up with the
green wire that runs to
connector (427).
7. Off At connector (117) (117), 86AR >100K Go to Locate short in
measure resistance for to 86AS. ohms. next circuit 86AR or
circuit 86AR to 86AS. step. 86AS, then repair.
8. Off At connector (427) install (117), 86AR <2 ohms. Go to Locate short in
jumper wire between to 86AS. next circuit 86AR or
circuits 86N and 86P. At step. 86AS, then repair.
connector (117) measure
resistance for circuit 86AR
to 86AS.
9. Off At connector (118) (118), 86AT >100K Go to Locate short in
measure resistance for to 86AU. ohms. next circuit 86AT or
circuit 86AT to 86AU. step. 86AU, then repair.
10. Off At connector (427) install (118), 86AT <2 ohms. Go to Locate short in
jumper wire between to 86AU. next circuit 86AT or
circuits 86V and 86W. At step. 86AU, then repair.
connector (118) measure
resistance for circuit 86AT
to 86AU.
11. Off Bunk speaker circuits
check good.

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3.5. LUGGAGE COMPARTMENT LIGHTS

Table 158 Luggage Compartment Lights
STEP KEY ACTION TEST SPEC. YES NO – OUT OF SPEC.
POINTS – IN
SPEC.
1. Off Remove fuse F8-D and F8-D. <1 ohm. Go to Locate cause of
check. next overload condition,
step. then repair. Replace
fuse.
2. Off Re-install fuse F8-D and F8-D, 14AP 12 ±1.5 Go to Locate cause of low
measure voltage at circuit to gnd. volts. next or no voltage in circuit
14AP to ground. step. 14AP from battery
stud (B2), then repair.
3. Off Disconnect conn. (906) (906), 63AA 12 ±1.5 Go to Locate cause of low
and at circuit 63AA to gnd. volts. next or no voltage in circuit
measure voltage to gnd. step. 63AA, then repair.
4. Off Reconnect (906) and (583), black 12 ± 1.5 Go to Locate cause of low
disconnect conn. (583). wire to gnd. volts. next or no voltage in circuit
At black wire, measure page. 63AJ or black wire,
voltage to ground. then repair.
5. Off Does the left compartment Go to Go to next step.
light illuminate? Step 10.
6. Off With luggage door (583), gray <2 Go to Replace defective
tipped up, measure wire to gray ohms. next left compartment light
resistance across the left wire. step. switch.
compartment light switch
at connector (583).
7. Off Disconnect connector (1287), 12 ± 1.5 Go to Locate cause of low
(1287) and reconnect 63AK to gnd. volts. next or no voltage in white
connector (583). With step. wire or circuit 63AK,
compartment door open, then repair.
measure voltage at conn.
(1287) circuit 63AK to
ground.
8. Off At conn. (1287) with (1287), 12 ± 1.5 Go to Locate open or poor
compartment door open, 63AK to volt.s next conn. in circuit
measure voltage from 63-GAK. page. 63-GAK, 11-GAF,
circuit 63AK to 63-GAK. 11-GBC, 11-GBD, or
11-GBE to ground
adapter (454), then
repair.
9. Off Repair or replace defective Go to
lamp or socket. next
step.
10. Off Does the right Go to Go to next step.
compartment light Step 15.
illuminate?

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Table 158 Luggage Compartment Lights (cont.)

STEP KEY ACTION TEST SPEC. YES NO – OUT OF SPEC.
POINTS – IN
SPEC.
11. Off With luggage door (587), gray <2 Go to Replace defective
tipped up, measure wire to gray ohms. next right compartment
resistance across the right wire. step. light switch.
compartment light switch
at conn. (587).
12. Off Disconnect conn. (1286) (1286), 12 ±1.5 Go to Locate cause of low
and reconnect conn. 63AE to gnd. volts. next or no voltage in white
(587). With compartment step. wire or circuit 63AE,
door open, measure then repair.
voltage at conn. (1286)
circuit 63AE to ground.
13. Off At conn. (1286) with (1286), 12 ±1.5 Go to Locate open or poor
compartment door open, 63AE to volts. next connection in circuit
measure voltage from 63-GD. step. 63-GD or 11-GAG,
circuit 63AE to 63-GD. then repair.
14. Off Repair or replace defective Go to
lamp or socket. next
step.
15. Off Does the lift—up bunk Go to Go to next step.
light illuminate? Step 20.
16. Off With lift—up bunk tipped (1304), dark <2 Go to Replace defective
up, measure resistance blue wire to ohms. next lift—up bunk light
across the lift—up bunk gray wire. step. switch.
light switch at conn.
(1304).
17. Off Disconnect conn. (1288) (1288), 12 ±1.5 Go to Locate cause of low
and reconnect conn. 63AM to gnd. volts. next or no voltage in white
(1304). With lift—up bunk step. wire or circuit 63AM,
open, measure voltage at then repair.
conn. (1288) circuit 63AM
to ground.
18. Off At conn. (1286) with (1286), 12 ±1.5 Go to Locate open or poor
lift—up bunk open, 63AM to volts. next connection in circuit
measure voltage from 63-GN. step. 63-GN or 11-GBC,
circuit 63AM to 63-GN. then repair.
19. Off Repair or replace defective Go to
lamp or socket. next
step.
20. Off Luggage compartment
and lift—up bunk lights
and circuits check good.

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3.6. POWER SALEM VENT

Table 159 Power Salem Vent
STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F10-B and F10-B. <1 ohm. Go to Locate cause of
check for open condition. next overload condition,
step. then repair. Replace
fuse.
2. Off Re-install fuse F10-B F10-B, 12 ± 1.5 Go to Locate cause of low
and measure voltage at 14AV to volts. next or no voltage in circuit
circuit 14AV to ground. gnd. step. 14AV, or 14AK from
battery stud (B2), then
repair.
3. Off Remove fuse 582-B and 582-B. <1 ohm. Go to Locate cause of
check for open condition. next overload condition,
step. then repair. Replace
fuse.
4. Off Re-install fuse 582-B 582-B, 12 ± 1.5 Go to Locate cause of low
and measure voltage at 14AX to volts. next or no voltage in circuit
circuit 14AX to gnd. gnd. step. 14AX, then repair.
5. Off Disconnect connector (595), 76M 12 ± 1.5 Go to Locate cause of low
(595), and at circuit 76M to gnd. volts. next or no voltage in circuit
measure voltage to gnd. step. 76M or 76K, then
repair.
6. Off At connector (595) (595), 76M 12 ± 1.5 Go to Locate open or poor
measure voltage from to 76-GM. volts. next connection in circuit
circuit 76M to 76-GM. step. 76-GM, 11-GAF,
11-GBC, 11-GBD,
or 11-GBE to gnd.
adapter (454), then
repair.
7. Off The power salem vent
circuits check good. If
power vent does not
function, replace it or
have it repaired.

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3.7. POWER SOURCE (SLEEPER)

Table 160 Power Source (Sleeper)
STEP KEY ACTION TEST SPEC. YES NO – OUT OF SPEC.
POINTS – IN
SPEC.
1. Off Remove fuse F10-C and F10 – C. <1 ohm. Go to Locate cause of
check for open condition. next overload condition,
step. then repair. Replace
fuse.
2. Off Re- install fuse F10-C and F10-C, 12 ± 1.5 Go to Locate cause of low
measure voltage at circuit 14AW to volts. next or no voltage in circuit
14AW to ground. gnd. step. 14AK or 14AW from
battery stud (B2), then
repair.
3. Off Does the right bulkhead Go to Go to next step.
auxiliary power source Step 7.
outlet good?
4. Off At right bulkhead auxiliary (789), 12 ± 1.5 Go to Locate cause of low
power source (789), black wire volts. next or no voltage in circuit
measure voltage from or 14AY to step. 14AY or black wire
black wire or circuit 14AY gnd. (with 57 inch bunk),
to ground. then repair.
5. Off At right bulkhead auxiliary (789), 12 ± 1.5 Go to Locate open or poor
power source, measure 86-GH or volts. next connection in white
voltage from circuit 86-GH black to step. wire (with 57 inch
or from black wire to white white wire. bunk), circuit 86-GH,
wire. 11-GAG, 11-GBC,
11-GBD, or 11-GBC
to gnd. adapter (454),
then repair.
6. Off Right bulkhead auxiliary Go to
power source circuits next
check good. If power step.
source will not function
properly, replace faulty or
corroded socket.
7. Off At control panel auxiliary (1306), 12 ± 1.5 Go to Locate cause of low
power source (1306), black wire volts. next or no voltage in circuit
measure voltage from or 14AZ to step. 14AZ or black wire
black wire or circuit 14AZ gnd. (with 57 inch bunk),
to ground. then repair.

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Table 160 Power Source (Sleeper) (cont.)

STEP KEY ACTION TEST SPEC. YES NO – OUT OF SPEC.
POINTS – IN
SPEC.
8. Off At control panel auxiliary (1306), 12 ± 1.5 Go to Locate open or poor
power source, measure 86-GN or volts. next connection in white
voltage from circuit 86-GN black to step. wire (with 57 inch
or from black wire to white white wire. bunk), circuit 86-GN,
wire. 11-GAE, 11-GN,
11-GAF, 11-GBC,
11-GBD, or 11-GBC
to gnd. adapter (454),
then repair.
9. Off control panel auxiliary
power source circuits
check good. If power
source will not function
properly, replace faulty or
corroded socket.

3.8. REFRIGERATOR WIRING

Table 161 Refrigerator Wiring
STEP KEY ACTION TEST SPEC. YES- NO-OUT OF SPEC.
POINTS INSPEC.
1. Off Remove fuse F10-A and F10-A. <1 ohm. Go to Locate cause of
check for open condition. next overload condition,
step. then repair. Replace
fuse.
2. Off Re-install fuse F10-A and F10-B, 12 ± 1.5 Go to Locate cause of low
measure voltage at circuit 14AV to volts. next or no voltage in circuit
14AV to ground. gnd. step. 14AV or 14AK from
battery stud (B2), then
repair.
3. Off Remove connector (613) Go to
from refrigerator On/Off next
switch. step.
4. Off Does the panel lamp Go to Go to next step.
illuminate on the Step 8.
refrigerator On/Off switch
when the ignition switch is
in the on or accessories
position?
5. Off At connector (613), with (613), 62X 12 ± 1.5 Go to Locate cause of low
the ignition switch on or to gnd. volts. next or no voltage in circuit
in accessories position, step. 62X from junction at
measure voltage from bunk blower relay,
circuit 62X to gnd. then repair.

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Table 161 Refrigerator Wiring (cont.)

STEP KEY ACTION TEST SPEC. YES- NO-OUT OF SPEC.
POINTS INSPEC.
6. Off At connector (613), with (613), 62X 12 ± 1.5 Go to Locate open or poor
the ignition switch on or to 62-GX. volts. next connection in circuits
in accessories position, step. 62-GX and 86-GK
measure voltage from to gnd adapter (506)
circuit 62X to 62-GX. and 11-GAF, 11-GBC,
11-GBD, or 11-GBE to
gnd adapter (454).
7. Off Replace faulty refrigerator Go to
On/Off switch. next
step.
8. Off Does the on indicator Go to Go to next step.
lamp illuminate on the Step 10.
refrigerator On/Off switch
when the switch is moved
to the on position?
9. Off Use the diode test function .6 to .8 Go to Replace defective
on the Fluke 88 VOM to volt diode next switch.
test the indicator. LED drop. step.
OK?
10. Off Measure resistance Refrig. <1 ohm. Go to Replace defective
across terminals 5 and 6 of On/Off next switch.
refrigerator On/Off switch switch, step.
when the switch is in the terminal 5
on position. to 6.
11. Off Re-install refrigerator (612), 12 ± 1.5 Go to Locate cause of low
On/Off switch. At 86AG to volts. next or no voltage in circuit
connector (612), with gnd. step. 86AG, then repair.
refrigerator switch in the
on position, measure
voltage from circuit 86AG
to gnd.
12. Off At connector (612), with (612), 12 ± 1.5 Go to Locate open or poor
refrigerator switch in the 86AG to volts. next connection in circuit
on position, measure 86-GR. step. 86-GR, then repair.
voltage from circuit 86AG
to 86-GR.
13. Off Refrigerator power source
circuits check good. If
power source will not
function properly, replace
faulty or corroded socket.

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3.9. TV/VCR WIRING

Table 162 TV/VCR Wiring
STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F10-D and F10-D. <1 ohm. Go to next Locate cause of
check for open condition. step. overload condition,
then repair. Replace
fuse.
2. Off Re-install fuse F10-D and F10-D, 12 ± 1.5 Go to next Locate cause of low
measure voltage at circuit 14AV to volts. step. or no voltage in circuit
14AV to ground. gnd. 14AV or 14AK from
battery stud (B2), then
repair.
3. Off Remove fuse 582-A and 582-A. <1 ohm. Go to next Locate cause of
check for open condition. step. overload condition,
then repair. Replace
fuse.
4. Off Re-install fuse 582-A and 582-A, 12 ± 1.5 Go to next Locate cause of low
measure voltage at circuit 14AX to volts. step. or no voltage in circuit
14AX to ground. gnd. 14AX, then repair.
5. Off At TV power source, circuit TV Power 12 ± 1.5 Go to next Locate cause of low
86AP, measure voltage source, volts. step. or no voltage in circuit
from black wire to ground. 86AP 86AP, or black wire,
black wire then repair
to gnd.
6. Off At TV power source, circuit TV Power 12 ± 1.5 Go to next Locate open or poor
86AP, measure voltage source, volts. step. connection in white
from black wire to white 86AP, wire circuit 86-GP,
wire. black wire 11-GAC, 11-GAD,
to white 11-GBD, or 11-GBE to
wire. ground adapter (454),
then repair.
7. Off TV power source circuits
check good. If power
source will not function
properly, replace faulty or
corroded socket.

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3.10. OVERHEAD CABINETS, ACCENT LIGHTS WIRING

Table 163 Overhead Cabinets, Accent Lights Wiring
STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
1. Off Remove fuse F10-D and F10-D. <1 ohm. Go to next Locate cause of
check for open condition. step. overload condition,
then repair. Replace
fuse.
2. Off Re-install fuse F10-D and F10-D, 12 ± 1.5 Go to next Locate cause of low
measure voltage at circuit 14AV to volts. step. or no voltage in circuit
14AV to ground. gnd. 14AV or 14AK from
battery stud (B2), then
repair.
3. Off Remove fuse 582-C and 582-C. <1 ohm. Go to next Locate cause of
check for open condition. step. overload condition,
then repair. Replace
fuse.
4. Off Re-install fuse 582-C and 582-C, 12 ± 1.5 Go to next Locate cause of low
measure voltage at circuit 14AX to volts. step. or no voltage in circuit
14AX to ground. gnd. 14AX, then repair.
5. Off Remove connector (1289) Go to next
from Accent Lights On/Off step.
switch.
6. Off Does the panel lamp Go to Step Go to next step.
illuminate on the Accent 9.
Lights On/Off switch when
the ignition switch is in
the on or accessories
position?
7. On At connector (1289), with (1289), 12 ± 1.5 Go to next Locate cause of low
the ignition switch on or 62Y to volts. step. or no voltage in circuit
in accessories position, gnd. 62Y from junction at
measure voltage from bunk blower relay,
circuit 62Y to gnd. then repair.
8. On At connector (1289), with (1289), 12 ± 1.5 Go to next Locate open or poor
the ignition switch on or 62Y to volts. step. connection in circuit
in accessories position, 62-GY. 62-GY, 11-GAF,
measure voltage from 11-GBC, 11-GBD,
circuit 62Y to 62-GY. or 11-GBE to gnd
adapter (454), then
repair.
9. Off Measure resistance Accent <1 ohm. Go to next Replace defective
across terminals 5 and 6 Lights step. switch.
of Accent Lights On/Off On/Off
switch when the switch is Sw.,
in on the position. terminal 5
to 6.

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Table 163 Overhead Cabinets, Accent Lights Wiring (cont.)

STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
10. Off Re-install (1289) Accent Go to Step Go to next step.
Lights On/Off switch. 22.
Does the Accent Lights
function OK?
11. Off Disconnect connector (1313), 12 ± 1.5 Go to next Locate cause of low
(1313), with Accent 63BD, volts. step. or no voltage in circuit
Lights switch in the on black wire 63BD or black wire,
position, measure voltage to gnd. then repair
at connector (1313) circuit
63BD, black wire to
ground.
12. Off At connector (1313), with (1313), 12 ± 1.5 Go to next Locate open or poor
Accent Lights switch in the 63–GBD, volts. step. connection in white
on position, measure black wire wire circuit 63-GBD, to
voltage from circuit to white ground adapter (454),
63-GBD, black wire to wire. then repair.
white wire.
13. Off Repair or replace defective Go to next
right accent lamp or step.
socket.
14. Off Disconnect connector (1312), 12 ± 1.5 Go to next Locate cause of low
(1312) and reconnector 63BC, volts. step. or no voltage in circuit
connector (1313), with black wire 63BC, or black wire,
Accent Lights switch in to gnd. then repair
the on position, measure
voltage at connector
(1312) circuit 63BC, black
wire to ground.
15. Off At connector (1312), with (1312), 12 ± 1.5 Go to next Locate open or poor
Accent Lights switch in the 63–GBC, volts. step. connection in white
on position, measure black wire wire circuit 63-GBC, to
voltage from circuit to white ground adapter (454),
63-GBC, black wire to wire. then repair.
white wire.
16. Off Repair or replace defective Go to next
center accent lamp or step.
socket.
17. Off Disconnect connector (1311), 12 ± 1.5 Go to next Locate cause of low
(1311) and reconnector 63BB, volts. step. or no voltage in circuit
connector (1312), with black wire 63BB, or black wire,
Accent Lights switch in to gnd. then repair
the on position, measure
voltage at connector
(1311) circuit 63BB, black
wire to ground.

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Table 163 Overhead Cabinets, Accent Lights Wiring (cont.)

STEP KEY ACTION TEST SPEC. YES – IN NO – OUT OF SPEC.
POINTS SPEC.
18. Off At connector (1311), with (1311), 12 ± 1.5 Go to next Locate open or poor
Accent Lights switch in the 63–GBB, volts. step. connection in white
on position, measure black wire wire circuit 63-GBB, to
voltage from circuit to white ground adapter (454),
63-GBB, black wire to wire. then repair.
white wire.
19. Off Repair or replace defective Go to next
left accent lamp or socket. step.
20. Off Disconnect connector (1310), 12 ± 1.5 Go to next Locate cause of low
(1310) and reconnector 63BB, volts. step. or no voltage in circuit
connector (1311), with black wire 63BB, or black wire,
Accent Lights switch in to gnd. then repair
the on position, measure
voltage at connector
(1310) circuit 63BB, black
wire to ground.
21. Off At connector (1310), with (1310), 12 ± 1.5 Go to next Locate open or poor
Accent Lights switch in the 63–GBB, volts. step. connection in white
on position, measure black wire wire circuit 63-GBB,
voltage from circuit to white 11-GAD, 11-GBD, or
63-GBB, black wire to wire. 11-GBC to ground
white wire. adapter (454), then
repair.
22. Off Reconnector connector
(1310), overhead cabinets
accent lights and circuits
check good.

4. COMPONENT LOCATIONS
B2 Battery Stud.. . .. .. . .. . .. .. . .. . .. .. . .. .. . .. . .. .. . .. .. . . . . . Power Distribution Panel
(43) Truck Body/Trailer Feed. .. .. . .. .. .. . .. .. .. . .. .. .. . . . . . Left Back of Cab, "B" Pillar
(117) Sleeper Box Control Panel. . . . . . . . . . . . . . . . . . . .. . . . . . Behind Sleeper Control Panel (Volume Control)
(118) Sleeper Box Control Panel. . . . . . . . . . . . . . . . . . . .. . . . . . Behind Sleeper Control Panel (Volume Control)
(220) Reading Light Ground Switch. . . . . . . . . . . . . . . . .. . . . . . Upper Bunk, Driver Side, Stop
(322) Left Bunk Jumper.. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. . . . . . Left Bunk
(323) Right Bunk Jumper.. . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . . . Right Bunk
(426) Radio Connector #1. . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . . . Radio Pigtail to Cab Harness
(427) Radio Connector #2. . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . . . . Radio Pigtail to Cab Harness
(428) Roof Connector #2. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Right Instrument Panel/Roof Connector to Cab
Harness
(429) Roof Connector #1. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Right Instrument Panel/Roof Connector to Cab
Harness
(441) Work Light Switch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Switch Cluster
(454) G2 Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(463) F8 Fuseblock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Fuse Panel

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(464) F10 Fuseblock. . . .. . . . . . . . .. . . . . . . .. . . . . . . . .. . . .. . . . . . At Fuse Panel

(474) Radio Remote Band Sel. . . . . . . . . . . . . . . . . . . . . . .. . . . . . (Inline) Pigtail At Rear of Radio
(483) Radio Remote Scan/Sel. . . . . . . . . . . . . . . . . . . . . . .. . . . . . (Inline) Pigtail At Rear of Radio
(498) Battery Adapter. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . .. . . . . . Power Distribution Panel
(504) Panel Light Feed Adapter. . . . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(502) Sleeper Dome Light Switch W/PRO
SLEEPER. . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . .. . . . . . At Roof, Center of Header Panel
(506) Panel Light Ground Adapter. . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(528) Right Rear Speaker. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Speaker Pigtail (Inline)
(529) Right Front Speaker.. . .. . .. .. . .. .. . .. .. . .. .. . ... . . . . . At Speaker Pigtail (Inline)
(530) Left Front Speaker .. .. . .. . .. . .. .. . .. . .. .. . .. . ... . . . . . At Speaker Pigtail (Inline)
(531) Left Rear Speaker.. . . . .. . . . . .. . . . .. . . . .. . . . .. . .. . . . . . At Speaker Pigtail (Inline)
(574) Left Slpr Speaker W/PRO SLPR. . . . . . . . . . . . .. . . . . . At Speaker Pigtail (Inline)
(575) Right Slpr Speaker W/PRO SLPR . . . . . . . . . . .. . . . . . At Speaker Pigtail (Inline)
(576) AM/FM Band Select W/PRO SLPR. . . . . . . . . .. . . . . . At Switch of Sleeper Box Control Panel
(582) Sleeper Fuse Block W/PRO SLPR . . . . . . . . . .. . . . . . In Left Luggage Compartment
(587) Rt Bunk Mercury Switch. . . . . . . . . . . . . . . . . . . . . . .. . . . . . Inside Right Luggage Compartment
(583) Lt Bunk Mercury Switch. . . . . . . . . . . . . . . . . . . . . . .. . . . . . Inside Left Luggage Compartment a
(594) Dome Light SW W/PRO SLPR. . . . . . . . . . . . . . .. . . . . . At Temperature Control Panel
(603) Fluorescent Bunk Light (Inline) W/PRO
SLPR. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . . . . Left Front Corner Near Top of Sleeper Box
(604) Reading Light W/PRO SLEEPER. . . . . . . . . . . .. . . . . . Center Left Side of Sleeper Box
(605) Under Cabinet Light W/PRO SLPR . . . . . . . . . .. . . . . . At Under Cabinet Light
(606) Auxiliary Fan (Inline) W/PRO SLPR. . . . . . . . . .. . . . . . Upper Right Front of Sleeper Box
(607) TV/VCR Conn. (Inline) W/PRO SLPR. . . . . . .. . . . . . Upper Right Rear of Sleeper Box
(608) TV Conn. (Inline) W/PRO SLPR. . . . . . . . .. . . . .. . . . . . Upper Right Rear of Sleeper Box
(610) Fluorescent Bunk Light W/PRO SLEEPER. ... . . . . . Upper Center Of Sleeper Box
(611) Auxiliary Fan W/PRO SLEEPER.. . .. .. .. . .. ... . . . . . Upper Right Front of Sleeper Box
(612) Refrig. (Inline) W/PRO SLEEPER. . . . . . . . . . . .. . . . . . Floor of Sleeper Between Cab & Left Luggage Comp.
(613) Refrigerator Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . At Switch of Sleeper Box Control Panel
(615) Fluorescent Bunk Light (Inline) W/Box
Sleeper. . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . .. . . . . . At Light Pigtail (Inline)
(616) Fluorescent Bunk Light W/Box Sleeper. . . . . .. . . . . . At Light Pigtail (Inline)
(617) Bunk Dome Light Switch . . . .. . . . . .. . . . .. . . . .. .. . . . . . At Light Pigtail (Inline)
(618) Reading Light W/Box Sleeper. . .. .. . .. . .. .. . ... . . . . . At Light Pigtail (Inline)
(624) Left Luggage Compartment Light W/Box
Sleeper. . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . .. . . . . . In Left Luggage Compartment
(625) Right Luggage Compartment Light W/Box
Sleeper. . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . .. . . . . . In Right Luggage Compartment
(629) Front Sleeper Speaker W/Box Sleeper. . . . . .. . . . . . At Speaker Pigtail
(630) Rear Sleeper Speaker W/Box Sleeper. . . . . . .. . . . . . At Speaker Pigtail
(634) Heater Blower & Power Source.. . . . . .. . . . .. . .. . . . . . Near Switch at Control Panel
(642) Sleeper to Roof Connector W/PRO
SLEEPER. . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . .. . . . . . At Lower Left Front Corner of Sleeper Box
(643) Sleeper to Roof Connector W/PRO
SLEEPER. . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . .. . . . . . At Lower Left Front Corner of Sleeper Box
(668) K Fuse Block W/Box Sleeper. . . . . . . . . . . . . . . . .. . . . . . In Left Luggage Compartment
(669) L Fuse Block W/Box Sleeper. .. . .. . .. . .. . .. . ... . . . . . In Left Luggage Compartment
(720) Lower Bunk Reading Light. . . . . . . . . . . . . . . . . . . .. . . . . . At Lower Bunk
(789) Right Auxiliary Power Source. . . . . . . . . . . . . . . . .. . . . . . Behind Passenger Seat at Front of Sleeper Bunk
(790) Auxiliary Power Source. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Jumper Harness Inline Connector With 57 Inch Bunk
Only
(906) PRO SLEEPER Lights/Speaker. . . . . . . . . . . . . .. . . . . . Left Rear of Cab, “B” Pillar

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(922) Trailer Socket #1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Rear of Cab, “B” Pillar

(923) Trailer Socket #2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Rear of Cab, “B” Pillar
(925) Trailer Socket #1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Rear of Cab, “B” Pillar
(926) Trailer Socket #2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Left Rear of Cab, “B” Pillar
(935) Work Light Connector. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . . . Left Rear of Cab, “B” Pillar
(942) PRO SLEEPER Connector.. . . .. . . .. . . .. . . .. . .. . . . . . Left Rear of Cab, “B” Pillar
(1286) Rt Luggage Light . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . Inside Right Luggage Compartment
(1287) Lt Luggage Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Inside Left Luggage Compartment a
(1288) Center Luggage Light .. . .. . .. . .. . .. . .. . .. . .. .. . . . . . Inside Center Luggage Compartment
(1289) Accent Lights ON/OFF Switch . . . . . . . . . . . . . .. . . . . . At Switch of Sleeper Box Control Panel
(1304) Lift—up Bunk Mercury Switch. . . . . . . . . . . . . . .. . . . . . Inside Center Luggage Compartment
(1305) Auxiliary Fan W/High Roof.. . . . . . . . . . . . . . . . . .. . . . . . Upper Right Front of Sleeper Box
(1306) Control Panel Auxiliary Power Source. . . . . .. . . . . . Jumper Harness Inline Connector With 57 Inch Bunk
Only
(1310) Overhead Cabinets Accent Lights. . . . . . . . . .. . . . . . Overhead Cabinets Control Panel
(1311) Left Accent Lights. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Overhead Cabinets
(1312) Center Accent Lights. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Overhead Cabinets
(1313) Right Accent Lights. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Overhead Cabinets
(1315) TV/VCR Conn. (Inline) W/PRO SLPR. . . . . .. . . . . . Upper Right Rear of Sleeper Box

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Figure 162 Auxiliary Fan Wiring With 51” Low Roof PRO SLEEPER
1. (611) SLEEPER ROOF HARNESS CIRCUITS 76L AND 76-GL TO CONNECTOR
2. SEE THE NEXT FIGURE FOR VIEW OF ARROW C

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Figure 163 Auxiliary Fan Wiring With 51” Low Roof PRO SLEEPER
1. AUXILIARY CIRCULATION FAN
2. (611) CONNECTOR AUXILIARY FAN HARNESS
3. LEFT “B” PILLAR TRIM PANEL

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Figure 164 Auxiliary Fan Wiring With 72” PRO SLEEPER & HIGH ROOF
1. CIRCUITS 76K AND 76-GK
2. (611) CONNECTOR
3. AUXILIARY CIRCULATION FAN

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Figure 165 Auxiliary Fan Wiring With PRO SLEEPER & SKYRISE
1. AUXILIARY CIRCULATION FAN
2. (611) RIGHT SIDE JUMPER HARNESS CIRCUITS 76K AND 76-GK CONNECTOR
3. SKYRISE ROOF JUMPER HARNESS
4. (323) CONNECTOR RIGHT SIDE ROOF JUMPER HARNESS TO SLEEPER ROOF
HARNESS
5. SLEEPER WIRING FOR PRO SLEEPER

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Figure 166 Radio Wiring With Low Roof and High Roof Bunk Speakers PRO SLEEPER
1. AM/FM CASSETTE RADIO
2. (529) RADIO SPEAKER
3. (575) AND (574) BUNK SPEAKERS
4. SLEEPER CONTROL PANEL (SEE FIGURES 169 & 170)
5. SLEEPER WIRING HARNESS
6. (642) ROOF HARNESS CONNECTOR
7. (531) RADIO SPEAKER
8. (906) CAB HARNESS TO SLEEPER HARNESS CONNECTOR
9. (530) RADIO SPEAKER
10. (528) RADIO SPEAKER
11. ANTENNA MULTIPLEXER
12. CAB BASE HARNESS

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Figure 167 Radio Wiring With High Roof And Upper Bunk Speakers PRO SLEEPER
1. (575) BUNK RIGHT SPEAKER CIRCUITS 86AY, 86AZ
2. ROOF HARNESS
3. (574) BUNK LEFT SPEAKER CIRCUITS 86AW, 86AX

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Figure 168 Radio Wiring With SKYRISE Bunk Speakers PRO SLEEPER
1. AM/FM CASSETTE RADIO
2. (529) RADIO SPEAKER
3. (575) AND (574) BUNK SPEAKERS
4. SLEEPER CONTROL PANEL (SEE FIGURES 169 & 170)
5. SLEEPER WIRING HARNESS
6. (642) ROOF HARNESS CONNECTOR
7. (531) RADIO SPEAKER
8. CAB HARNESS TO SLEEPER HARNESS CONNECTOR (906)
9. (530) RADIO SPEAKER
10. (528) RADIO SPEAKER
11. ANTENNA MULTIPLEXER
12. CAB BASE HARNESS

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Figure 169 Radio Wiring With PRO SLEEPER (With Headset Jack)
1. HEADSET ADAPTER
2. SLEEPER CONTROL PANEL
3. SLEEPER CONTROL PANEL
4. (118) CONNECTOR CIRCUITS 86AT, 86AU, 86AY, 86AZ
5. (117) CONNECTOR CIRCUITS 86AR, 86AS, 86AW, 86AX
6. (577) CONNECTOR
7. SLEEPER WIRING HARNESS
8. (576) CONNECTOR

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Figure 170 Radio Wiring With PRO SLEEPER (Without Headset Jack)
1. SLEEPER CONTROL PANEL
2. SLEEPER CONTROL PANEL
3. (118) CONNECTOR CIRCUITS 86AT, 86AU, 86AY, 86AZ
4. (117) CONNECTOR CIRCUITS 86AR, 86AS, 86AW, 86AX
5. SLEEPER WIRING HARNESS

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Figure 171 Fluorescent Light And Reading Light High Roof and Low Roof PRO SLEEPER
1. (603) FLUORESCENT LIGHT
2. (607) TV/VCR CONNECTOR
3. (606) TO AUXILIARY FAN
4. (720) READING LIGHT
5. (604) READING LGHT (HIGH ROOF ONLY)
6. UNDER CABINET LIGHT
7. SLEEPER ROOF HARNESS

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Figure 172 Fluorescent Light and Reading Light Wiring with High Roof PRO SLEEPER and Upper
Bunk
1. TO FLUORESCENT LIGHT
2. TO TV/VCR AND AUXILIARY FAN
3. (720) UPPER READING LIGHT
4. (604) LOWER READING LIGHT
5. (605) UNDER CABINET LIGHT
6. SLEEPER BOX ROOF HARNESS

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Figure 173 Fluorescent Light And Reading Light SKYRISE PRO SLEEPER
1. TO TV/VCR AND AUXILIARY FAN
2. (603) FLUORESCENT LIGHT
3. (604) READING LGHT
4. (322) SLEEPER ROOF JUMPER
5. (220) READING LIGHT GND SWITCH
6. (720) READING LIGHT
7. (605) UNDER CABINET LIGHT CIRCUIT 63–AR, 63–GR
8. SLEEPER ROOF HARNESS

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Figure 174 Wiring and Luggage Compartment Lights PRO SLEEPER With High Roof, Low Roof
and SKYRISE

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1. SLEEPER HARNESS TO RIGHT SIDE OF SLEEPER

2. WORK LIGHTS
3. POWER SALEM VENT
4. BREAKOUT TO POWER VENT
5. SLEEPER CONTROL PANEL
6. SLEEPER GROUND STUD
7. LUGGAGE COMPARTMENT LIGHT
8. LUGGAGE COMPARTMENT LIGHT, DOOR SWITCH
9. TO REFRIGERATOR
10. TO ROOF HARNESS
11. TO ROOF HARNESS
12. (906) SLEEPER CONNECTOR #1
13. (942) SLEEPER CONNECTOR #2

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Figure 175 Wiring, Luggage Compartment Lights And Right Aux. Power Source PRO SLEEPER With
High Roof, Low Roof and SKYRISE
1. SLEEPER HARNESS (DRIVER SIDE WIRING)
2. SLEEPER HARNESS (PASSENGER SIDE WIRING)
3. CONNECTOR (609)
4. LUGGAGE COMPARTMENT SWITCH (MERCURY)
5. SLEEPER HARNESS
6. (588) LUGGAGE COMPARTMENT LIGHT
7. TO SLEEPER HARNESS ON LEFT SIDE OF SLEEPER
8. (789) RIGHT AUXILIARY POWER SOURCE

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Figure 176 Fuse and Relay Wiring PRO SLEEPER With High Roof, Low Roof and SKYRISE
1. 5 AMP REFRIGERATOR FUSE
2. 10 AMP AUXILIARY BLOWER FUSE
3. 20 AMP TV FUSE
4. MAIN SLEEPER HARNESS
5. MEDIUM SPEED RELAY
6. HIGH SPEED RELAY
7. LABEL

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Figure 177 Bunk Light Wiring PRO SLEEPER With High Roof, Low Roof and SKYRISE
1. CONTROL PANEL
2. BUNK LIGHT SWITCH
3. (594) CONNECTOR CIRCUITS 63-GE, 63-GF, 63-GJ, 63-GK, 63–GZ AND 62Z
4. SLEEPER HARNESS

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Figure 178 Refrigerator Wiring PRO SLEEPER With High Roof Or Low Roof W/118” Sleeper Only
1. CONTROL PANEL
2. SLEEPER WIRING HARNESS
3. (612) REFRIGERATOR POWER SOURCE

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Figure 179 Refrigerator Wiring PRO SLEEPER With High Roof Or Low Roof W/118” Sleeper Only
1. SLEEPER CONTROL PANEL
2. (613) REFRIGERATOR ON/OFF SWITCH
3. SLEEPER WIRING HARNESS CIRCUITS 62X, 62–GX, 86–GK, 86AV AND 86AG

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Figure 180 TV and Antenna Installation PRO SLEEPER With 72” High Roof W/Upper Bunk
1. (607) TV/VCR POWER SOURCE CIRCUITS 86AP, 86–GP
2. TV ANTENNA
3. SLEEPER TV/VCR WIRING HARNESS
4. SEE FIGURE 184 FOR VIEW OF ARROW D
5. SEE FIGURE 184 FOR VIEW OF CIRCLE C

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Figure 181 TV/VCR Power Switch Wiring

1. SLEEPER CONTROL PANEL
2. (590) TV/VCR POWER SWITCH
3. (590) TV/VCR POWER SWITCH
4. SLEEPER WIRING HARNESS

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Figure 182 TV And Antenna Installation Sky—Rise PRO SLEEPER No Upper Bunk
1. (607) TV/VCR POWER SOURCE CIRCUITS 86AP, 86-GP
2. TV ANTENNA
3. SLEEPER CONTROL PANEL SEE FIGURE 181
4. SLEEPER HARNESS

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Figure 183 TV And Antenna Installation Sky-Rise PRO SLEEPER With Upper Bunk
1. (607) TV/VCR POWER SOURCE CIRCUITS 86AP, 86–GP
2. TV ANTENNA
3. SLEEPER TV/VCR WIRING HARNESS
4. SEE FIGURE 184 FOR VIEW OF ARROW D
5. SEE FIGURE 184 FOR VIEW OF CIRCLE C

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Figure 184 TV And Antenna Installation 72 Inch High Roof, Sky-Rise PRO SLEEPER With Upper Bunk
1. (607) TV/VCR POWER SOURCE CIRCUITS 86AP, 86-GP
2. SLEEPER TV/VCR HARNESS

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Figure 185 Overhead Cabinets, Accent Lights Installation High Roof And EAGLE PRO SLEEPER
1. (1313) RIGHT ACCENT LIGHTS
2. (1312) CENTER ACCENT LIGHTS
3. (1311) LEFT ACCENT LIGHTS
4. (310) CONNECTOR ACCENT LIGHTS CIRCUITS 62BB, 62–GBB
5. SLEEPER HARNESS TO ACCENT LIGHTS ON/OFF SWITCH (1289)

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Table of Contents

1. DESCRIPTION. .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .. . . .. . .. . .. . .561
1.1. HVAC CONTROL-CAB. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. .. . .. .. . .. .. .561
1.2. HEATER-BUNK WITH STANDARD TEMPERATURE CONTROL. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . .561
1.3. HEATER-BUNK WITH THERMOSTAT TEMPERATURE CONTROL. .. .. .. . .. .. .. .. .. . .. .. .. .. .. .561

2. OPERATION.. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. . .. .. .. .. .561
2.1. AIR CONDITIONER-CAB . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .561
2.2. BLOWER-CAB . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .562
2.3. AIR DISTRIBUTION-CAB.. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .. . .. .. . .. .. . .. .. . .. .. . .. .. . .. .. .563
Temperature Control.. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .563
Air Distribution Selection. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .563
Recirculation. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .563
2.4. HEATER-BUNK WITH STANDARD TEMPERATURE CONTROL. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . .564
2.5. HEATER-BUNK WITH THERMOSTAT TEMPERATURE CONTROL. .. .. .. . .. .. .. .. .. . .. .. .. .. .. .565

3. TROUBLESHOOTING. .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .566
3.1. AIR CONDITIONER-CAB . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .567
3.2. BLOWER-CAB . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . . .. . . .572
3.3. TEMPERATURE CONTROL-CAB . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . . .. . . . . . . .. . . . . . . . .578
3.4. AIR DISTRIBUTION MOTOR-CAB . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .579
3.5. RECIRCULATION MOTOR-CAB . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .579
3.6. HEATER-BUNK AUXILIARY BLOWER . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . .. . . . .. . . . .580
3.7. HEATER-BUNK WITH STANDARD TEMPERATURE CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .585
3.8. HEATER-BUNK WITH THERMOSTAT TEMPERATURE CONTROL .. . . . . .. . . . .. . . . . .. . . . . .. . . . .587

4. COMPONENT LOCATIONS. .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. . .. .. . .. . .. . .. .589

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1. DESCRIPTION
Refer to Truck Service Manual S16023 AIR CONDITIONER – HEATER SYSTEM: 9100i, 9200i, 9400i, 9900i
MODELS for information on removal and installation of components.

1.1. HVAC CONTROL-CAB

The HVAC control module, on the instrument panel, provides three knobs and two buttons (only one button
is used on models without the sleeper thermostat temperature control) which can be set to activate the AC
compressor, control cab temperature, select cab blower speed and select the desired air distribution.

The blower control knob on the left side of the control allows the operator to select one of four blower speeds.

The temperature control knob in the center of the HVAC control module controls a stepper motor in the heater
box allowing the operator to determine the mixture of hot and cold air available at the air ducts in the cab.

The mode control knob on the right side allows the operator to control air distribution. This is performed by a
stepper motor in the air ducts. The operator may select air flow to the defrost duct (when defrost is selected
the AC compressor will be activated), mixed lower duct and defrost duct, lower heat duct, mixed lower and
upper duct, and upper duct. The MAX position controls a recirculation stepper motor which will recirculate air
to speed up cooling of the cab. Air flow may be turned off by selecting OFF.

The AC button will enable or disable the AC compressor.

The BUNK button will shut off the bunk blower and all sleeper HVAC controls.

1.2. HEATER-BUNK WITH STANDARD TEMPERATURE CONTROL

The bunk heater system provides a blower system in the bunk to circulate heating or cooling air. Off, low,
medium or high speed blower settings are selectable from the bunk. The standard temperature control allows
the occupant of the sleeper to regulate operation of the bunk HVAC damper door in the heater box under the
passenger seat. It is not an automatic system. Note that the A/C must be turned on and off at the cab switch.

1.3. HEATER-BUNK WITH THERMOSTAT TEMPERATURE CONTROL

The bunk heater system provides a blower system in the bunk to circulate heating or cooling air. Off, low,
medium or high speed is selectable from the bunk. The thermostat temperature control allows the occupant of
the sleeper to select a temperature that the thermostat will then automatically maintain by regulating the bunk
HVAC damper door in the heater box under the passenger seat. The system also includes a switch, at the
sleeper control panel, for activating the air conditioning compressor.

2. OPERATION
Refer to the HEATER AND AIR CONDITIONER circuit diagrams in CTS-5298 or S08225.

2.1. AIR CONDITIONER-CAB

When the ignition switch is on, power is applied to circuit 75BR of HVAC control connector (1057). When the
AC button is pushed in or the defrost mode is selected, 12 volts will be applied from connector (1057) on
circuit 77W (and also through a diode and circuit 77S on models with AC control in the sleeper) to energize
A/C control relay (144).

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562 14 HEATER AND AIR CONDITIONER

If the vehicle is equipped with a sleeper A/C On/Off switch, A/C control relay (144) can also be energized when
the bunk heater blower switch (593) is not in the off position and the sleeper A/C switch (905) is on. The switch
will illuminate when it is on. Power flows from switch (593) on circuits 77L, 77AB and 77AC through switch
(905) to circuits 77M and 77K to energize the relay.

Power from fuse F1–B will flow through the relay on circuit 77H to connector (162) of the heater box pigtail.
From (162) it can flow through circuit 77C and 77P to feed the low pressure safety switch, circuits 77C and
77N to feed the high pressure safety switch, and 77B to feed the thermal switch. If the refrigerant pressure is
greater than the low pressure cut off switch, and less than the high pressure cut off switch, circuit 77R will not
have power applied. Thus, A/C relay (463–R6) normally closed (N.C.) contacts remain closed and while the
thermal switch contacts remain closed, power will flow from the thermal switch through circuit 77F, A/C relay
(463–R6) contacts, and circuit 77C to energize the refrigerant compressor clutch.

When the evaporator temperature cools to below 30° ± 2° (-1° ± 1°C), the thermal switch contacts will open
cutting off the flow of power to the compressor clutch. This will keep the evaporator from freezing over. If
either of the safety pressure switches close, the A/C relay will energize and its contacts will open breaking
power to the compressor clutch.

With the air conditioning relay (463–R6) energized, power is interrupted to the refrigerant compressor
clutch. Thus, the compressor is shut down, and will not restart until the refrigerant pressure is back within
operating range.

2.2. BLOWER-CAB
Power is supplied to (B2) battery stud, circuits 14H, 14Z, fuse F1–C and circuit 75A to the main control
relay (463–R5). When the ignition switch is on, power is applied to circuit 62P of HVAC control connector
(1057). When the HVAC control is not in the OFF position, 12 volts is applied to the coil of main control relay
(463–R5). The ground path for the main control relay is circuits 13–GT, 77–G, 58–GA and 11–G to right dash
panel ground stud. This energizes the main control relay (463–R5) and allows power to flow through the relay
contacts and circuit 75B to blower control switch (1056).

When the blower control switch (1056) is moved to the low position, there is no input from the switch to resistor
block (27). Power from main control relay (463–R5) will be applied through circuit 75BL, 75C, connector
(162), 75C to resistor block (27) terminal C. Power from the resistor block will be applied through circuit 75T,
connector (161), circuit 75T, high speed relay (462–R2) N.C. contacts, circuit 75F, connector (161) and circuit
75F to the blower motor. This causes the blower motor to run at low speed. The blower motor ground path
is through circuit 75–G, connector (161), circuits 75–G and 75–GL to connector (1057) of the HVAC control
module. Power flows through these circuits when the blower switch is in any position other than HIGH, as long
as the middle knob of the HVAC control module is not in the OFF position.

When the blower control switch (1056) is moved to the medium low position, power will flow through the
switch, circuit 75BH, connector (161), circuit 75M to resistor block (27) terminal A. Power from the resistor
block, terminal B, will be applied through circuit 75T, connector (161), circuit 75T, high speed relay (462–R2)
N.C. contacts, circuit 75F, connector (161) and circuit 75F to the blower motor. This causes the blower motor
to run at medium low speed. The blower motor ground path is through circuit 75–G, connector (161), circuits
75–G and 75–GL to connector (1057) of the HVAC control module.

When the blower control switch (1056) is moved to the medium high position, power will flow through the
switch on circuit 75N to the coil of medium high speed relay (462-R3). This energizes the medium high
speed relay (462–R3) which is grounded through circuits 75–GC, 50–GB and 11–G to the right dash panel
ground stud. Power from main control relay (462–R2), on circuit 75BL and 75D, will be applied to heater box
pigtail connector (1060) on circuit 75M. Power will be applied to the resistor block from connector (1060) on
circuit75BH. Power from the resistor block will be applied through circuit 75T, connector (161), circuit 75T, high

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speed relay (462–R2) N.C. contacts, circuit 75F, connector (161) and circuit 75F to the blower motor. This
causes the blower motor to run at medium high speed. The blower motor ground path is through circuit 75–G,
connector (161), circuits 75–G and 75–GL to connector (1057) of the HVAC control module.

When the blower control switch (1056) is moved to the high position, power will flow through the switch on
circuit 75H to the high speed relay (462–R2). This energizes the high speed relay (462–R2) which is grounded
through circuits 75–GB, 75–GC, 50–GB and 11–G to the right dash panel ground stud. This allows power to
flow from (B2) battery stud through circuits 14H, 14X, fuse F1–A, circuit 75, high speed relay (462–R2) N.O.
contacts, circuit 75F, connector (161), and circuit 75F to the blower motor. This causes the blower to run at
high speed. The blower motor ground path is through circuit 75–G, connector (161), circuits 75–G and 75–GL
to connector (1057) of the HVAC control module.

2.3. AIR DISTRIBUTION-CAB

Temperature Control

Cab temperature is controlled by a stepper motor in the heater box which controls the mixture of hot and cold air.

12 volts is supplied from fuse F9-D on circuit 75BC, circuit 75BJ, terminal A of connector (162), and 75BJ to
the stepper motor

The stepper motor ground path is through circuit 75–GL, connector (161), circuits 75–G and 75–GL to terminal
12 on connector (1057) of the HVAC control module.

The control voltage from the HVAC control module originates on terminal 3, circuit 75BE and is applied to
heater box connector (1060) and the stepper motor.

Air Distribution Selection

Cab air distribution is controlled by a stepper motor in the cab duct work which directs air flow to the desired
vents. The air distribution motor is located behind the instrument panel in front of the driver.

12 volts are supplied from fuse F9-D on circuit 75BC and circuit 75BK to the stepper motor.

The stepper motor ground path is through circuit 75–GM and circuit 75–GL to terminal 12 on connector (1057)
of the HVAC control module.

The control voltage from the HVAC control module originates on terminal 6 of (1057), circuit 75BF and is
applied to the stepper motor.

Recirculation

Recirculation of cab air is controlled by a stepper motor in the cab duct work which directs air flow between
internal and external air. The recirculation motor is located below the kick panel in front of the passenger seat.

12 volts is supplied from fuse F9-D on circuit 75BC and circuit 75BM to the stepper motor

The stepper motor ground path is through circuit 75–GK and circuit 75–GL to terminal 12 on connector (1057)
of the HVAC control module.

The control voltage from the HVAC control module originates on terminal 7, circuit 75BG and is applied to
the stepper motor.

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2.4. HEATER-BUNK WITH STANDARD TEMPERATURE CONTROL

When key switch (40) is moved to the ignition position, power is applied to I2 ignition adapter (495), circuit
13AT and the coil of auxiliary blower relay (147) through the “BUNK” switch in HVAC control (1057). The
ground path for the auxiliary blower relay is circuits 13–GAT and 11–GBC to ground adapter (454). This
energizes the auxiliary bunk blower relay (147) and allows power to flow from (B2) battery stud through circuits
14AK and 14AU, 15A fuse F10–B (location may vary), circuit 75AX, auxiliary bunk relay (147) N.O. contacts,
circuit 75AS, connector (906), circuits 75AS and 75AR to bunk heater blower switch (593).

When the bunk heater blower switch (593) is moved to the low speed position, power flows through circuit
75AC, connector (49), circuit 75AC, resistor and thermofuse assembly, circuit 75AT, connect (48), circuit
75AT, sleeper high speed relay (584) N.C. contacts, circuit 75AF, connector (48) and circuit 75AF to the
sleeper blower motor (1053).

This causes the blower motor to run at low speed. The blower motor ground path is circuit 75–GA, connector
(48), circuits 75–GA, 11–GBD, and 11–GBC to ground adapter (454).

When the bunk blower switch (593) is moved to the medium speed position, power flows through circuit 75AN
to the sleeper medium speed relay (585). The ground path for the sleeper medium speed relay (585) is circuits
75–GN, 11–GBD, and 11–GBC to ground adapter (454). This energizes the sleeper medium speed relay (585)
and allows power to flow from (B2) battery stud through circuits 14AK, 14AU, fuse F10–A (location may vary),
circuits 75AW, 75AB, sleeper medium speed relay (585) N.O. contacts, circuit 75AM, connector (48), circuit
75AM, resistor and thermofuse assembly (N/L), circuit 75AT, connector (48), circuit 75AT, sleeper high speed
relay (584) N.C. contacts, circuit 75AF, connector (48), and circuit 75AF to sleeper blower motor. This causes
the blower motor to run at medium speed. The blower ground path is circuit 75–GA, connector (48), circuit
75–GA, 11–GBD, and 11–GBC to ground adapter (454).

When the bunk blower switch (593) is moved to the high speed position, power flows through the switch, circuit
75AH to the sleeper high speed relay (584). The ground path for the sleeper high speed relay (584) is circuits
75–GH, 75–GN, 11–GBD, and 11–GBC to ground adapter (454).

This energizes the sleeper high speed relay (584) and allows power to flow from (B2) battery stud through
circuits 14AK and 14AU, 30A fuse F10–A (location may vary), circuit 75AW, connector (942), circuits 75AW,
75AD, sleeper high speed relay (584) N.O. contacts, circuit 75AF, connector (48) and circuit 75AF to sleeper
blower motor. This causes the blower motor to run at high speed.

The blower ground path is circuit 75–GA, connector (48), circuits 75–GA, 11–GBD and 11–GBC to ground
adapter (454).

When the key switch (40) is moved to the ignition position and the blower switch (593) is not off, power is
also made available by the auxiliary bunk relay (147) to circuit 75AS, connector (906), circuit 75AS, switch
(592), and circuit 75AL to sleeper temperature control connector (592). The ground path for the sleeper
temperature control is through connector (592), circuit 75-GS, 11–GAE to sleeper ground stud (746), circuit
11–GAN, connector (942) and circuit 11–GAN to B-pillar ground stud.

When the bunk heater blower switch (593) is moved to the high, medium or low positions, power flows through
circuit 77L, connector (905) and 75AL to sleeper temperature control (592). This allows the voltage from the
sleeper temperature control to control the heater box flat pack.

Power is made available by fuse F-9D to circuits 75BC and 75BJ, connector (162) and circuit 75BJ to the
heater box damper flat pack (stepper motor). The heater box damper flat pack is grounded through circuit
75–GL, connector (161), circuits 75–G and 11–G to right dash panel ground stud. The flat pack receives a
variable voltage from the sleeper temperature control through connector (592), circuit 75K, connector (906),

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circuit 75K, connector (162) and circuit 75K. Thus, the damper blends hot and cold air as selected by the
sleeper temperature control.

When cooling is required in the sleeper and the cab A/C switch is not in the on position, the cab switch must
be moved to the on position by the driver or sleeper occupant. Thus, the A/C compressor will engage (the
compressor will cycle with the thermal switch) and cooling will be available for the sleeper blower.

NOTE – This is the standard manual temperature control. The output of the system does not change
with changes in temperature.

2.5. HEATER-BUNK WITH THERMOSTAT TEMPERATURE CONTROL

When key switch (40) is moved to the ignition position, power is applied to I2 ignition adapter (495), circuit
13AT and the coil of auxiliary blower relay (147) through the “BUNK” switch in HVAC control (1057). The
ground path for the auxiliary blower relay is circuits 13–GAT and 11–GBC to ground adapter (454). This
energizes the auxiliary bunk blower relay (147) and allows power to flow from (B2) battery stud through circuits
14AK and 14AU, 15A fuse F10–B (location may vary), circuit 75AX, auxiliary bunk relay (147) N.O. contacts,
circuit 75AS, connector (906), circuits 75AS and 75AR to bunk heater blower switch (593).

When the bunk heater blower switch (593) is moved to the low speed position, power flows through circuit
75AC, connector (49), circuit 75AC, resistor and thermofuse assembly, circuit 75AT, connect (48), circuit
75AT, sleeper high speed relay (584) N.C. contacts, circuit 75AF, connector (48) and circuit 75AF to the
sleeper blower motor (1053).

This causes the blower motor to run at low speed. The blower motor ground path is circuit 75–GA, connector
(48), circuits 75–GA, 11–GBD, and 11–GBC to ground adapter (454).

When the bunk blower switch (593) is moved to the medium speed position, power flows through circuit 75AN
to the sleeper medium speed relay (585). The ground path for the sleeper medium speed relay (585) is circuits
75–GN, 11–GBD, and 11–GBC to ground adapter (454). This energizes the sleeper medium speed relay (585)
and allows power to flow from (B2) battery stud through circuits 14AK, 14AU, fuse F10–A (location may vary),
circuits 75AW, 75AB, sleeper medium speed relay (585) N.O. contacts, circuit 75AM, connector (48), circuit
75AM, resistor and thermofuse assembly (N/L), circuit 75AT, connector (48), circuit 75AT, sleeper high speed
relay (584) N.C. contacts, circuit 75AF, connector (48), and circuit 75AF to sleeper blower motor. This causes
the blower motor to run at medium speed. The blower ground path is circuit 75–GA, connector (48), circuit
75–GA, 11–GBD, and 11–GBC to ground adapter (454).

When the bunk blower switch (593) is moved to the high speed position, power flows through the switch, circuit
75AH to the sleeper high speed relay (584). The ground path for the sleeper high speed relay (584) is circuits
75–GH, 75–GN, 11–GBD, and 11–GBC to ground adapter (454).

This energizes the sleeper high speed relay (584) and allows power to flow from (B2) battery stud through
circuits 14AK and 14AU, 30A fuse F10–A (location may vary), circuit 75AW, connector (942), circuits 75AW,
75AD, sleeper high speed relay (584) N.O. contacts, circuit 75AF, connector (48) and circuit 75AF to sleeper
blower motor. This causes the blower motor to run at high speed.

The blower ground path is circuit 75–GA, connector (48), circuits 75–GA, 11–GBD and 11–GBC to ground
adapter (454).

When the key switch (40) is moved to the ignition position and the blower switch (593) is not off, power is
also made available by the auxiliary bunk relay (147) to circuit 75AS, connector (906), circuit 75AS, switch
(592), and circuit 75AL to sleeper temperature control connector (592). The ground path for the sleeper

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566 14 HEATER AND AIR CONDITIONER

temperature control is through connector (592), circuit 75-GS, 11–GAE to sleeper ground stud (746), circuit
11–GAN, connector (942) and circuit 11–GAN to B-pillar ground stud.

When the bunk heater blower switch (593) is moved to the high, medium or low positions, power flows through
circuit 75AL to the auto temperature control module (592). This allows the voltage from the auto temperature
control module to control the heater box flat pack (stepper motor).

Power is made available by fuse F-9D to circuits 75BC and 75BJ, connector (162) and circuit 75BJ to the
heater box damper flat pack (stepper motor). The heater box damper flat pack is grounded through circuit
75–GL, connector (161), circuits 75–G and 11–G to right dash panel ground stud. The flat pack receives a
variable voltage from the sleeper temperature control through connector (592), circuit 75K, connector (906),
circuit 75K, connector (162) and circuit 75K. Thus, the damper blends hot and cold air as selected by the
sleeper temperature control.

When the key switch (40) is in ignition position and the bunk heater blower switch (593) is in low, medium or
high position, power is applied to circuit 77L and the sleeper A/C On/Off switch (905). When the switch is
moved to the on position, the switch indicator lamp illuminates. The ground path for the lamp is through circuits
75–GBB, 75–GBA and 77–GL to the sleeper ground stud. When the switch is moved to on position, power is
also supplied to the A/C control relay (144) by way of connector (905), circuit 77M, connector (906) and circuit
77M. Thus, the A/C compressor will engage, if it is not already running (the compressor will cycle with the
thermal switch), and cooling will be available for the sleeper blower.

NOTE – This is the optional thermostat temperature control circuit. The output of the system changes
with changes in temperature to maintain the temperature of the sleeper at the thermostat setting.

3. TROUBLESHOOTING
Refer to the HEATER AND AIR CONDITIONER circuit diagrams in CTS-5298 or S08225.

A. Before beginning these test procedures, make sure the vehicle batteries are at 75% state of
charge (SOC) or higher. This represents an open circuit voltage (OCV) of 13.4 volts. Batteries
with an OCV of 12 volts or less are either completely discharged or have a dead cell.
B. Before beginning these test procedures, check any light or indicator lamp filaments that are
suspected of being open (burned out). This is done to avoid unnecessary extensive circuit checks.
C. Before beginning these test procedures, inspect all connectors for loose or damaged pins,
wires, etc. Refer to TEST EQUIPMENT AND CONNECTOR REPAIR section in GROUP 08 —
ELECTRICAL in the CTS-5000 Master Service Manual.
D. When the technician determines that a fuse is blown, while checking its condition, he is directed
to locate the cause of the overload condition and to repair it. While no further instruction on this
procedure is listed in the diagnostic tables, the common procedure is as follows: isolate sections
of the circuit, by disconnecting connectors, and measure the resistance to ground to find the circuit
that is shorted to ground. Then locate the damaged spot in the wire or connector and repair.
E. Diagnostics for circuits that are malfunctioning by sticking in the on position are generally not
covered in detail. It is assumed that the technician knows to check for a malfunctioning switch,
relay, or solenoid.

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 14 HEATER AND AIR CONDITIONER 567

3.1. AIR CONDITIONER-CAB

Table 164 Air Conditioner-Cab
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. On Remove fuse F1-B and F1-B <1 ohm. Go to next Locate cause of
check for open condition. step. overload condition,
then repair. Replace
fuse.
2. On At circuit 14Z measure F1-B, 14Z 12 ± 1.5 Go to next Locate cause of low
voltage to ground. to ground volts. step. or no voltage in circuit
14Z or 14H from (B2)
battery stud, then
repair.
3. On Re-install fuse F1-B. Circuit 12 ± 1.5 Go to next Locate open or short to
Remove A/C control relay 77T at volts. step. ground in circuit 77T,
(144). Measure voltage the relay then repair.
between circuit 77T at the socket
relay socket and ground. and
ground.
4. On Insure the mode control 77W of 12 ± 1.5 Go to Step Go to next step.
on the HVAC control the main volts. 8.
is not in off position control
and AC button is on relay and
(Leave switches in these ground.
positions throughout this
table). Measure voltage
between circuit 77W at
A/C control relay and
ground.
5. Off Disconnect HVAC (1057), >100K Go to next Locate short to ground
control connector (1057). 77W and ohms. step. in circuit 77W.
Measure the resistance ground.
between circuit 77W or
(77S, isolation diode and
77W with Pro Sleeper)
and ground.
6. Off Measure the resistance (1057), <1 ohm. Go to next Locate short to open
between HVAC control 77W or step. in circuit 77W or (77S,
connector (1057) circuit (77S, isolation diode and
77W or (77S, isolation isolation 77W with Pro Sleeper) .
diode and 77W with Pro diode
Sleeper) and A/C control and 77W
relay (144). with Pro
Sleeper)
and
(144).

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568 14 HEATER AND AIR CONDITIONER

Table 164 Air Conditioner-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
7. Off/On Move key switch to (1057), 12 ± 1.5 Replace Locate cause of
ignition position. At 75BR to volts. defective missing ground at
(1057) measure voltage 75-GL. HVAC 75-GL or low or no
from circuit 75BR to control voltage in circuit 75BR,
75-GL. (1057). 75BC or fuse F9-D,
then repair.
8. Off At A/C control relay (144), <1 ohm. Go to next Locate open or poor
(144) measure resistance 77-GS step. connection in circuit
between circuit 77-GS and 77-GS, 11-GQ or 11-GF
and ground. ground. to left cab ground (56F),
then repair.
9. Off Bench test A/C control (144), pin <1 ohm. Go to next Replace defective A/C
relay (144) by measuring 30 to 87A. step. control relay (144).
resistance from pin 30 to
87A.
10. Off Bench test A/C control Energized <1 ohm. Go to next Replace defective A/C
relay (144) by applying (144), pin step. control relay (144).
+12V to pin 86, and 30 to 87.
ground to pin 85, and
measuring resistance
from pin 30 to 87.
11. Off/ On Re-install A/C control (162), 12 ± 1.5 Go to next Locate cause of low
relay (144) and 77H to volts. step. or no voltage in circuit
disconnect connector ground. 77H, then repair.
(162). Switch ignition to
on position. At connector
(162) circuit 77H, not
going to heater box,
measure voltage to
ground.
12. Off/ On At connector (162), (463-R6), 12 ± 1.5 Go to next Locate open or short to
not going to heater 77F to volts. step. ground in circuit 77F.
box, install a jumper ground.
between circuits 77F
and 77H. Remove
air conditioning relay
(463-R6). Turn ignition
to on. Measure voltage
between (463-R6) circuit
77F and ground.

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 14 HEATER AND AIR CONDITIONER 569

Table 164 Air Conditioner-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
13. Off/ On Remove jumper and (463-R6), 12 ± 1.5 Go to Step Go to next step.
reconnect (162). Turn 77F to volts. 18.
ignition to on. Measure ground.
voltage between
(463-R6) circuit 77F
and ground. Evaporator
temperature must be
greater than 34°F (1.5°C).
14. Off Disconnect thermal Across <1 ohm. Go to next Replace defective
switch (N/L) and measure freeze step. thermal switch (N/L).
resistance from terminal switch
1 to 2. Evaporator (N/L).
temperature must be
greater than 34°F (1.5°C).
15. Off At connector. (N/L), (162), <1 ohm. Go to next Locate open or poor
removed from thermal 77B to step. connection in circuits
switch, Install a jumper 77F. 77B or 77F, then repair.
between circuit 77B and
77F. At connector (162)
circuit 77B measure
resistance between
circuit 77B and 77F.
16. Off At connector (N/L), (162), >100K Go to next Locate short in circuit
removed from thermal 77F to ohms. step. 77B, 77F or the thermal
switch, measure ground. switch, then repair.
resistance from circuit
77F to ground.
17. Off/ On Remove jumper and (463-R6), 12 ± 1.5 Go to next Locate cause of low
reconnect thermal switch 77F to volts. stop. or no voltage in circuit
(N/L) and connector ground. 77F, then repair.
(162). Remove A/C relay
(463-R6). Move key
switch to ignition position.
At (463-R6) circuit 77F,
measure voltage to
ground.
18. On With switches still set, at (463-R6), 12 ± 1.5 Go to next Locate open or poor
relay socket (463-R6), 77F to volts. step. connection in circuit
measure voltage from 77-G 77-G, 58-GA, or 11-G
circuit 77F to 77-G. to right dash panel gnd
stud, then repair.

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570 14 HEATER AND AIR CONDITIONER

Table 164 Air Conditioner-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
19. Off/ On At relay socket (463-R6) Go to next Go to Step 32.
install jumper wire from step.
circuit 77F to 77C. Set
HVAC control (1075) A/C
switch to on, Mode switch
to any position but OFF,
and key switch to ignition
position. Did A/C clutch
engage (click once)?
20. On With switches still set, (N/L), 12 ± 1.5 Go to next Locate cause of low
disconnect low pressure 77P to volts. step. or no voltage in circuit
safety switch (N/L) and ground. 77C or 77P.
measure voltage from
circuit 77P to ground.
21. On With switches still set, (N/L), 12 ± 1.5 Go to next Locate cause of low
disconnect high pressure 77N to volts. step. or no voltage in circuit
safety switch (N/L) and ground. 77N, then repair.
measure voltage from
circuit 77N to ground.
22. On At high pressure safety (N/L), 77J 12 ± 1.5 Go to next Locate cause of low
switch (N/L) circuit 77J, to ground. volts. step. or no voltage in circuit
measure voltage to 77J, then repair.
ground.
23. Off Measure resistance of Across >100K Go to next If refrigerant charge is
low pressure safety low ohms. step. within limits, replace
switch (N/L). Insure pressure defective low pressure
refrigerant charge is safety switch.
within limits. switch.
24. Off Measure resistance of Across >100K Go to next If refrigerant charge is
high pressure safety high ohms. step. within limits, replace
switch (N/L). Insure pressure defective high pressure
refrigerant charge is safety switch.
within limits. switch.
25. Off Measure resistance Circuit <1 ohm. Go to next Locate open in circuits
between circuit 77E of 77E of step. 77 or 77R.
the low pressure safety the low
switch connector and pressure
circuit 77R of the heater safety
box harness connector switch
(162). and 77R
of heater
box
harness
conn.
(162).

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 14 HEATER AND AIR CONDITIONER 571

Table 164 Air Conditioner-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
26. Off Measure resistance from Circuit <1 ohm. Go to next Locate open in circuit
circuit 77J of the high 77J of step. 77J.
pressure safety switch the high
connector to circuit 77R pressure
of the heater box harness safety
connector (162). switch
to circuit
77R of
the heater
box
harness
conn.
(162).
27. Off Measure resistance from Circuit >100K Go to next Locate short to ground
circuit 77R of the heater 77R of ohms. step. on circuit 77R, 77E, or
box harness connector the heater 77J.
(162) to ground. box
harness
connector
(162) to
ground.
28. Off/ On At connector (162), (463-R6), 12 ± 1.5 Go to next Locate open or short to
not going to heater 77R to volts. step. ground in circuit 77R.
box, install a jumper ground.
between circuits 77H
and 77R. Turn ignition
to on. Measure voltage
between (463-R6) circuit
77F and ground.
29. Off Measure resistance (463-R6), <1 ohm. Go to next Locate open in circuit
between (463-R6) circuit 77-G to step. 77-G.
77-GF and ground. ground.
30. Off Bench test A/C relay A/C relay <1 ohm. Go to next Replace defective
(463-R6) by measuring (463-R6), step. relay.
resistance from terminal 30 to 87A.
30 to 87A.
31. Off Bench test A/C relay Energized <1 ohm. Go to next Replace defective
(463-R6) by applying (463-R6), step. relay.
+12V to terminal 85 and 30 to 87.
ground to terminal 86.
Measure resistance from
terminal 30 to 87.

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572 14 HEATER AND AIR CONDITIONER

Table 164 Air Conditioner-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
32. On With switches still set, (2), 77C 12 ± 1.5 Go to next Locate cause of low
disconnect connector (2) to ground. volts. step. or no voltage in circuit
and at circuit 77C [coming 77C, then repair.
from (463-R6)] measure
voltage to ground.
33. On With switches still set, N/L), 77C 12 ± 1.5 Go to next Locate cause of low
reconnect connector to ground. volts. step. or no voltage in circuit
(2) and disconnect 77C, then repair.
compressor connector
(N/L). At (N/L) circuit
77C measure voltage to
ground.
34. On Wth switches still set, Go to next Replace defective A/C
reconnect connector step. compressor clutch.
(N/L) at the A/C
compressor clutch. Does
the clutch engage (click
once)?
35. Off Air conditioner circuits
check good. Remove
test jumper, re-install
relay and reconnect the
separated connectors.

3.2. BLOWER-CAB
Table 165 Blower-Cab
STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
1. On When the ignition is on Go to Step Go to next step.
and the mode select 19.
switch is not off, does the
blower run in low speed
position?
2. Off/ On Remove main control (463-R5), 12 ± 1.5 Go to step Go to next step.
relay (463-R5). Insure 13BH to volts. 4.
the HVAC control mode ground.
switch is not off and turn
ignition on. Measure
voltage between circuit
13BH and ground.

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 14 HEATER AND AIR CONDITIONER 573

Table 165 Blower-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
3. Off/ On Remove connector (1057), 12 ± 1.5 Replace Locate cause of
(1057). Move key switch 75BR to volts. defective missing ground at
to ignition position. At 75-GL. HVAC 75-GL or low or no
(1057) measure voltage control voltage in circuit 75BR,
from circuit 75BR to (1057). 75BC or fuse F9-D,
75-GL. then repair.
4. On At relay socket (463-R5), (463-R5), 12 ± 1.5 Go to next Locate open or poor
measure voltage from 13BH to volts step. connection in circuit
circuit 13BH to 13-GT. 13-GT. 13-GT, 77-G, 58-GA
or 11-G to right dash
panel gnd, then repair.
5. Off Remove fuse F1-C and F1-C <1 ohm. Go to next Locate cause of
check for open condition. step. overload condition,
then repair. Replace
fuse.
6. Off At F1-C circuit 14Z F1-C, 14Z 12 ± 1.5 Go to next Locate cause of low
measure voltage to to ground. volts. step. or no voltage in circuit
ground. 14H or 14Z, then repair.
7. Off Re-install fuse F1-C and Relay 12 ± 1.5 Go to next Locate cause of low
at relay socket (463-R5), (463-R5), volts. step. or no voltage in circuit
measure voltage from 75A to 75A, then repair.
circuit 75A to ground. ground.
8. Off Bench test main control Relay <1 ohm. Go to next Replace defective main
relay (463-R5) by (463-R5), step. control relay.
measuring resistance pin 30 to
from pin 30 to 87A. 87A.
9. Off Bench test main control Energized <1 ohm. Go to next Replace defective main
relay (463-R5) by (463-R5), step. control relay.
applying +12 volts to pin 30 to
pin 86, ground to pin 85 87.
and measuring resistance
from pin 30 to 87.
10. Off/ On Re-install (463-R5). (162), 12 ± 1.5 Go to next Locate cause of low
Disconnect heater circuit volts. step. or no voltage in circuit
connector (162). Turn 75C and 75C, then repair.
igniton on and measure ground.
voltage between (162)
circuit 75C and grround.
11. Off Remove high speed Relay <1 ohm. Go to next Replace defective high
relay (462-R2). Bench (462-R2), step. speed relay (462-R2).
test relay by measuring pin 30
resistance from pin 30 and 87A
and 87A.

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574 14 HEATER AND AIR CONDITIONER

Table 165 Blower-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
12. Off/ On Reconnect heater (27), 12 ± 1.5 Go to next Locate cause of low
connector (162). Inside circuit volts. step. or no voltage in circuit
heater box disconnect 75C and 75C, then repair.
resistor block (27). Turn ground.
igniton on, and measure
the Voltage between
circuit 75C and ground.
13. Off Measure resistance Resistor .97 to Go to next Replace defective
between resistor block block 1.31 step. resistor block.
and thermofuse assembly (27), ohms.
(27), terminal C to B. terminal
C to B.
14. Off Disconnect blower Terminal <1 ohm. Go to next Locate open in circuits
motor connector (209). B of step. 75T or 75F.
Measure resistance connector
between terminal B (27) and
of connector (27) and terminal A
terminal A of (209). of (209).
15. Off Measure resistance Terminal >100K Go to next Locate short to ground
between terminal B B of ohms. step. in circuits 75T or 75F.
of connector (27) and connector
ground. (27) and
ground.
16. Off Reconnect resistor block (27), < 1 ohm. Go to next Locate open in circuit
(27). measure resistance 75-G to step. 75-G, then repair.
between (209), circuit ground.
75-G and ground.
17. Off Reconnect resistor block (27), < 1 ohm. Go to next Locate open in circuit
(27). measure resistance 75-G to step. 75-G, then repair.
between (209), circuit ground.
75-G and ground.
18. Off Bench check blower Blower Low speed Replace defective
motor by applying 12 motor blower blower motor.
volts to terminal A of runs. circuits
the motor connector and check
ground to terminal B. good.
19. Off Test blower control switch (1056), <1 ohm. Go to next Replace defective
(1056) by placing switch terminal step. blower switch.
in medium low position D to E.
and measuring resistance
from switch terminal D to
E.

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 14 HEATER AND AIR CONDITIONER 575

Table 165 Blower-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
20. Off Test blower control switch (1056), <1 ohm. Go to next Replace defective
(1056) by placing switch terminal step. blower switch.
in medium high position A to E.
and measuring resistance
from switch terminal A to
E.
21. Off Test blower control switch (1056), <1 ohm. Go to next Replace defective
(1056) by placing switch terminal step. blower switch.
in high position and E to C.
measuring resistance
from switch terminal E to
C.
22. Off/On Re-install blower switch Go to step Go to next step.
(1056). Move key switch 26.
to on position. Does
blower motor run at
medium low speed when
blower switch is set to
medium low positon?
23. Off/ On Disconnect connector (161), 12 ± 1.5 Go to next Locate cause of low
(161). With key switch 75BH to volts. step. or no voltage in circuit
in ignition position and ground. 75BH, then repair.
blower switch in medium
low speed position,
measure voltage from
circuit 75BH, coming
from (1056), to ground.
24. Off/ On Reconnect connector (27), 75M 12 ± 1.5 Go to next Locate cause of low
(161). Disconnect to ground. volts. step. or no voltage in circuit
resistor and thermofuse 75M, then repair.
assembly (27). With key
switch in ignition position
and blower switch in
medium low position,
measure voltage from
circuit 75M to ground.
25. Off At resistor block and Resistor .85 to Med ium Replace defective
thermofuse assembly block 1.13 low speed resistor block.
(27), measure resistance (27), ohms. blower
from terminal A to B. terminal circuits
A to B. check
good.

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576 14 HEATER AND AIR CONDITIONER

Table 165 Blower-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
26. Off/ On Move key switch to on Go to Step Go to next step.
position. Does blower 34.
motor run at medium
high speed when blower
switch is set to medium
high positon?
27. Off/ On Remove medium high (462-R3), 12±1.5 Go to next Locate cause of
speed relay (462-R3). circuit volts. step. incorrect voltage on
Turn ignition on. Measure 75M to circuit 75M or open in
voltage from circuit 75M 75-GC. circuit 75-GC.
to circuit 75-GC.
28. On At (462-R3) socket, (462-R3), 12±1.5 Go to next Locate cause of
measure voltage from circuit volts. step. incorrect voltage on
circuit 75D to 75-GC. 75D to circuit 75D from the
75-GC. main control relay
(463-R5).
29. Off Bench test medium high (462-R3), <1 ohm. Go to next Replace defective
speed relay (462-R3) by pin 30 to step. medium high speed
measuring resistance 87A. relay (462-R3).
from pin 30 to 87A.
30. Off Bench test medium high Energized <1 ohm. Re-install Replace defective
speed relay (462-R3) by (462-R3), relay. Go medium high speed
applying +12 volts to pin pin 30 to to next relay (462-R3).
86, ground to pin 85, and 87. step.
measuring resistance
from pin 30 to 87.
31. Off/ On Disconnect connector (1060), 12 ± 1.5 Go to next Locate cause of low or
(1060). With key switch 75BH to volts. step. no voltage on circuit
in ignition position and ground. 75BH, then repair.
blower switch in medium
high speed position.
Measure voltage from
circuit 75BH to ground.
32. Off/ On Reconnect (1060). (27), 12 ± 1.5 Go to next Locate cause of low
Disconnect resistor 75BH to volts. step. or no voltage in circuit
block and thermofuse ground. 75BH, then repair.
assembly (27). With key
switch in ignition position
and blower switch in
medium low position,
measure voltage from
circuit 75BH to ground.

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 14 HEATER AND AIR CONDITIONER 577

Table 165 Blower-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES - IN NO - OUT OF SPEC.
POINTS SPEC.
33. Off At resistor block and Resistor .62 to .84 Medium Replace defective
thermofuse assembly block ohm. high resistor block.
(27), measure resistance (27), speed
from the terminal which terminal blower
connects to circuit 75BH which circuits
to terminal B. connects check
to circuit good.
75BH to
terminal
B.
34. On Move key switch to (462-R2), 12 ± 1.5 Go to next Locate cause of low
ignition position, blower 75H to volts. step. or no voltage in circuit
switch to high speed ground. 75H, then repair.
position, and at (462-R2)
circuit 75H, measure
voltage to ground.
35. On With switches still set, (462-R2), 12 ± 1.5 Go to next Locate open or poor
at (462-R2), measure 75H to volts. step. connection in circuit
voltage from circuit 75H 75-GB. 75-GB, 75-GC, 50-GB
to 75-GB. or 11-G to right dash
panel ground, then
repair.
36. On Move key switch to (462-R2), 12 ± 1.5 Go to next Locate cause of low
ignition position, blower 75 to volts. step. or no voltage in circuit
switch to high speed ground. 75H, from fuse F1-A,
position, and at (462-R2) then repair.
circuit 75, measure
voltage to ground.
37. Off Bench test high speed (462)/R2, <1 ohm. Go to next Replace defective high
relay (462-R2) by pin 30 to step. speed relay (462-R2).
measuring resistance 87A.
from pin 30 to 87A.
38. Off Bench test high speed Energized <1 ohm. High Replace defective high
relay (462-R2) by (462)/R2, speed speed relay (462-R2).
applying +12 volts to pin 30 to blower
pin 86, ground to pin 85, 87. circuits
and measuring resistance check
from pin 30 to 87. good.

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578 14 HEATER AND AIR CONDITIONER

3.3. TEMPERATURE CONTROL-CAB

Table 166 Temperature Control-Cab
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off/ Disconnect connector (1060), The Go to Locate cause of
On (1060). Move key switch circuit voltage next incorrect voltage in
to ignition position. 75BE to should step. circuit 75BE, from
Measure voltage ground. vary HVAC control (1057),
from circuit 75BE to as the then repair.
ground while sliding the control is
temperature control from varied.
one extreme to the other.
2. Off/ Reconnect connector Between The Go to Locate cause of
On (1060). Remove the circuit voltage next incorrect voltage in
connector to the cab 75BE and should step. circuit 75BE, then
stepper motor in the ground vary repair.
heater box. Turn ignition as the as the
on. Measure the voltage temperature control is
between circuit 75BE control is varied.
and ground as the varied.
temperature control is
varied.
3. On At cab stepper motor Locate 12 ± 1.5 Go to Locate cause of
connector, measure cause of volts. next incorrect voltage in
voltage from circuit 75BJ incorrect step. circuit 75BJ, then
to ground. voltage repair.
in circuit
75BJ, then
repair.
6. Off Measure resistance Cab <1 ohm. Go to Locate open in circuit
from cab stepper motor stepper next 75-GL, then repair.
connector circuit 75-GL motor step.
to ground. connector
circuit
75-GL to
ground.
7. Off/ Re-install the cab stepper Stepper Cab Replace cab stepper
On motor connector. Turn motor tem- motor.
ignition on. Check if the operates. pera-
stepper motor operates ture
while the temperature controls
control is varied from on check
extreme to the other. good.

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 14 HEATER AND AIR CONDITIONER 579

3.4. AIR DISTRIBUTION MOTOR-CAB

Table 167 Air Distribution Motor-Cab
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off/ Disconnect air distribution (1058), The Go to Locate cause of
On motor connector (1058). circuit 75BF voltage next incorrect voltage in
Move key switch to ground. should step. circuit 75BF, from
to ignition position. change HVAC control (1057),
Measure voltage from as the then repair.
circuit 75BF to ground control is
while selecting different changed.
positions with the mode
selector.
3. On At air distribution motor Voltage 12 ± 1.5 Go to Locate cause of
connector (1058), from circuit volts. next incorrect voltage in
measure voltage from 75BK to step. circuit 75BK, then
circuit 75BK to ground. ground. repair.
6. Off Measure resistance (1058) <1 ohm. Go to Locate open in circuit
air distribution motor circuit next 75-GM, then repair.
connector (1058) circuit 75-GM to step.
75-GM to ground. ground.
7. Off/ Re-install connector Air dis- Cab Replace air distribution
On (1058). Turn ignition on. tribu- tion air dis- motor.
check if the air distribution motor tribu-
motor operates while operates. tion
the mode selector is controls
changed. check
good.

3.5. RECIRCULATION MOTOR-CAB

Table 168 Recirculation Motor-Cab
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off/ Disconnect recirculation (1059), The Go to Locate cause of
On motor connector (1059). circuit voltage next incorrect voltage in
Move key switch 75BG to should step. circuit 75BG, from
to ignition position. ground. change HVAC control (1057),
Measure voltage from as the then repair.
circuit 75BG to ground control is
while changing from MAX changed.
to OFF with the mode
selector.
3. On At recirculation motor Voltage 12 ± 1.5 Go to Locate cause of
connector (1059), from circuit volts. next incorrect voltage in
measure voltage from 75BM to step. circuit 75BM, then
circuit 75BM to ground. ground. repair.

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580 14 HEATER AND AIR CONDITIONER

Table 168 Recirculation Motor-Cab (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
6. Off Measure resistance (1059) <1 ohm. Go to Locate open in circuit
between recirculation circuit next 75-GK, then repair.
motor connector (1059) 75-GK to step.
circuit 75-GK to ground. ground.
7. Off/ Re-install connector Recir- Cab Replace air distribution
On (1059). Turn ignition on. cula- tion recir- recirculation motor.
check if the recirculation motor cula-
motor operates while operates. tion
the mode selector is controls
changed. check
good.

3.6. HEATER-BUNK AUXILIARY BLOWER

Table 169 Heater-Bunk Auxiliary Blower
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. On Does the blower run in Go to Go to the next step.
either the low, medium or Step
high fan position? 10.
2. Off/ Remove auxiliary bunk (147), 13AT 12 ± 1.5 Go to Locate cause of low
On blower relay (147). Move to ground. volts next or no voltage in circuit
key switch to ignition step. 13AT from HVAC
position and turn on bunk control (1057) and
switch (1057), if equipped. ignition adapter (495),
At circuit 13AT measure then repair.
voltage to ground.
3. On At relay socket (147), (147), 13AT 12 ± 1.5 Go to Locate open or poor
measure voltage from to 13-GAT. volts. next connection in circuit
circuit 13AT to 13-GAT. step. 13-GAT or 11-GBC to
ground adapter (454),
then repair.
4. Off At (B2) battery stud (B2) to 12 ± 1.5 Go to Locate cause of low
measure voltage to ground. ground. volts. next or no voltage at (B2)
step. battery stud, then
repair.
5. Off Remove fuse F10-B F10-B <1 ohm. Go to Locate cause of
(location may vary) and next overload condition,
check for open condition. step. then repair, Replace
fuse.
6. Off Re-install F10-B and at F10-B, 12 ± 1.5 Go to Locate cause of low
circuit 14AU measure 14AU to volts. next or no voltage in circuit
voltage to ground. ground. step. 14AK or 14AU, then
repair.

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 14 HEATER AND AIR CONDITIONER 581

Table 169 Heater-Bunk Auxiliary Blower (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
7. Off At relay socket (147), (147), 75AX 12 ± 1.5 Go to Locate cause of low
measure voltage from to ground. volts. next or no voltage in circuit
circuit 75AX to ground. step. 75AX, then repair.
8. Off Bench test auxiliary bunk Relay (147), <1 ohm. Go to Replace defective
blower relay (147) by pin 30 to next auxiliary bunk blower
measuring resistance from 87A. step. relay.
pin 30 to 87A.
9. Off Bench test auxiliary bunk Energized <1 ohm. Go to Replace defective
blower relay (147) by (147), pin next auxiliary bunk blower
applying +12V to pin 86, 30 to 87. step. relay.
ground to pin 85 and
measuring resistance from
pin 30 to 87.
10. Off/ Re-install (147) and (593), 75AR 12 ±1.5 Go to Locate cause of low
On disconnect switch (593). to ground. volts. next or no voltage in circuit
Move key switch to ignition step. 75AS or 75AR, then
position and at (593) circuit repair.
75AR, measure voltage to
ground.
11. Off Test bunk heater blower (593), <1 ohm. Go to Replace defective
switch (593) by placing terminal B next blower switch.
switch in low speed to L, and B step.
position, and measuring to C.
resistance from switch
terminal B to L, and B to C.
12. Off Test bunk heater blower (593), <1 ohm. Go to Replace defective
switch (593) by placing terminal B next blower switch.
switch in medium speed to M, and step.
position and measuring B to C.
resistance from switch
terminal B to M, and B to C.
13. Off Test bunk heater blower (593), <1 ohm. Go to Replace defective
switch (593) by placing terminal B next blower switch.
switch in high speed to H, and step.
position and measuring B to C.
resitance from switch
terminal B to H, and B to C.
14. Off/ Re-install blower switch Go to Go to next step.
On (593). Move key switch to Step
on position. Does blower 22.
motor run at low speed
when blower switch is set
to low position?

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582 14 HEATER AND AIR CONDITIONER

Table 169 Heater-Bunk Auxiliary Blower (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
15. Off/ Disconnect connector (N/L) (N/L), 75AC 12 ± 1.5 Go to Locate cause of low
On and with the key switch to ground. volts. next or no voltage in circuit
in ignition position and step. 75AC, connector
blower switch in low speed (N/L) or circuit 75AC,
position, measure voltage then repair.
from circuit 75AC [coming
from(593)] to ground.
16. Off/ Disconnect resistor and (N/L), 75AC 12 ± 1.5 Go to Locate cause of low
On thermofuse assembly (N/L) to ground. volts. next or no voltage in circuit
and with key switch in step. 75AC, then repair.
ignition position and blower
switch in low position,
measure voltage from
circuit 75AC to ground.
17. Off At blower resistor and Blower 1.1 to 1.3 Go to Replace defective
thermofuse assembly resistor ohms. next blower resistor.
(N/L), measure resistance (N/L), step.
from terminal 1 to 2. terminal 1
to 2.
18. Off At blower resistor and Blower .25 to .45 Go to Replace defective
thermofuse assembly resistor ohm. next blower resistor.
(N/L), measure resistance (N/L), step.
from terminal 2 to 3. terminal 2
to 3.
19. Off/ Reconnect blower resistor (48), 75AT 12 ± 1.5 Go to Locate cause of low
On and disconnect connector to ground. volts. next or no voltage in circuit
(48). With key switch step. 75AT, then repair.
in ignition position and
blower switch in low
speed position, at (48)
circuit 75AT [going to (N/L)]
measure voltage to ground.
20. On Remove sleeper high (584), 75AT 12 ± 1.5 Go to Locate cause of low
speed relay (584) and to ground. volts. next or no voltage in circuit
reconnect connector (48). step. 75AT, then repair.
At circuit 75AT measure
voltage to ground.
21. Off Bench test high speed (584), pin <1 ohm. Go to Replace defective
relay (584) by measuring 30 to 87A. next sleeper high speed
resistance from pin 30 to step. relay (584).
87A.

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 14 HEATER AND AIR CONDITIONER 583

Table 169 Heater-Bunk Auxiliary Blower (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
22. Off Bench test high speed Energized <1 ohm. Go to Replace defective
relay (584) by applying (584), pin next sleeper high speed
+12V to pin 86, ground 30 to 87. step. relay (584).
to pin 85 and measuring
resistance from pin 30 to
87.
23. On Move key switch to ignition (584), 75AH 12 ± 1.5 Go to Locate cause of low
positon, blower switch to ground. volts. next or no voltage in circuit
to high speed position, step. 75AH, then repair.
and at (584) circuit 75AH,
measure voltage to ground.
24. Off At (584) install a test (48), 75AF <1 ohm. Go to Locate open or poor
jumper from circuit 75AF to ground. next connection in circuit
to 75-GH. Disconnect step. 75AF, then repair.
connector (48) and at
circuit 75AF [coming from
(584)], measure resistance
to ground.
25. Off At connector (48) measure (48), 75-GA <1 ohm. Go to Locate open or poor
resistance from circuit to ground. next connection in circuit
75-GA [going to (454)] to step. 75-GA or 11-GBD
ground. 11-GBC to ground
adapter (454), then
repair.
26. Off/ Reconnect connector (48) Sleeper 12 ± 1.5 Go to Locate cause of low
On and disconnect circuit blower volts. next or no voltage in circuit
75AF from sleeper blower motor, 75AF step. 75AF, then repair.
motor. Move key switch to to ground.
ignition position, blower sw.
to low speed position and
at 75AF measure voltage
to ground.
27. On Measure voltage from Sleeper 12 ± 1.5 Go to Locate open or poor
circuit 75AF to 75-GA. blower volts. next connection in circuit
motor, 75AF step. 75-GA, then repair.
to 75-GA.
28. Off/ With ignition key in off Go to Replace defective
On position, reconnect circuit next blower motor.
75AF. Move key switch to step.
ignition position and with
blower switch in low speed
position, does blower run?

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584 14 HEATER AND AIR CONDITIONER

Table 169 Heater-Bunk Auxiliary Blower (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
29. Off/ Remove medium speed (585), 75AN 12 ± 1.5 Go to Locate cause of low
On relay (585), move key to ground. volts. next or no voltage in circuit
switch to ignition position step. 75AN, then repair.
and move blower switch to
medium speed. At circuit
75AN, measure voltage to
ground.
30. Off Remove fuse F10-A F10-A <1 ohm. Go to Locate cause of
(location may vary) and next overload condition,
check for open condition. step. then repair, Replace
fuse.
31. Off Re-install fuse F10-A. At (585), 75AB 12 ± 1.5 Go to Locate cause of low
relay socket (585) and to ground. volts. next or no voltage in circuit
circuit 75AB, measure step. 75AW or 75AB, then
voltage to ground. repair.
32. Off Bench test medium speed (585), pin <1 ohm. Go to Replace defective
relay (585) by measuring 30 to 87A. next medium speed relay
resistance from pin 30 to step. (585).
87A.
33. Off Bench test medium speed Energized <1 ohm. Go to Replace defective
relay (585) by applying (585), pin next medium speed relay
+12V to pin 86, ground 30 to 87. step. (585).
to 85, and measuring
resistance from pin 30 to
87.
34. Off/ Disconnect connector (48), (48), 75AM 12 ± 1.5 Go to Locate cause of low
On re-install medium speed to ground. volts. next or no voltage in circuit
relay (585), move key step. 75AM, then repair.
switch to ignition position
and blower switch to low
speed position. At (48)
circuit 75AM [coming from
(585)], measure voltage to
ground.
35. On Disconnect resistor and (N/L), 75AM 12 ± 1.5 Go to Locate cause of low
thermofuse assembly (N/L) to ground. volts. next or no voltage in circuit
and reconnect connector step. 75AM, then repair.
(48). At (N/L) circuit 75AM,
measure voltage to ground.

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 14 HEATER AND AIR CONDITIONER 585

Table 169 Heater-Bunk Auxiliary Blower (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
36. Off Reconnect resistor and (584), 75AD 12 ± 1.5 Go to Locate cause of low
thermofuse connector to ground. volts. next or no voltage in circuit
(N/L) and remove high step. 75AD, then repair.
speed relay (584). At (584)
cir. 75AD, measure voltage
to ground.
37. Off Re-install high speed relay
(584). Heater blower
circiuts check good.

3.7. HEATER-BUNK WITH STANDARD TEMPERATURE CONTROL

Table 170 Heater-Bunk With Standard Temperature Control
STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off/ Disconnect connector (592), 12 ± 1.5 Go to Locate cause of low
On (592). Move key switch terminal A volts. next or no voltage in circuit
to ignition position and to ground. step. 75AL, then repair.
move bunk heater blower
switch to low. At harness
connector, measure
voltage from terminal A to
ground.
2. On At harness connector (592), 12 ± 1.5 Go to Locate open or poor
(592) measure voltage terminal A volts. next connector in circuit
from terminal A to C. to C. step. 75-GS, 11–GAE to
sleeper ground stud
(746) or 11-GAN to
B-pillar ground stud,
then repair.
3. Off At connector (592), (592), 9K ohms Go to Replace defective
pigtail to sleeper terminal A to 11K next sleeper temperature
temperature control, to C. ohms. step. control.
measure resistance from
terminal A to C.
4. Off At connector (592) (592), 39K Go to Replace defective
and pigtail to sleeper terminal B ohms. next sleeper temperature
temperature control, to C. step. control.
measure resistance from
terminal B to C with
control rotated fully CCW.

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586 14 HEATER AND AIR CONDITIONER

Table 170 Heater-Bunk With Standard Temperature Control (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF SPEC.
POINTS SPEC.
5. Off At connector (592) (592), 39K Go to Replace defective
and pigtail to sleeper terminal A ohms. next sleeper temperature
temperature control, to B step. control.
measure resistance from
terminal A to B with
control rotated fully CW.
6. Off Disconnect connector (592), <1 ohm. Go to Locate open in circuit
(162). Measure terminal next 75K then repair.
resistance from (592) B to (162) step.
terminal B to (162) terminal B.
terminal B.
7. Off/ Re-install connector (162) 12 ± 1.5 Go to Locate cause of low
On (592). Turn key switch terminal A volts. next or no voltage in circuit
to ignition position. to ground. step. 75L, then repair.
Measure voltage from
(162) terminal A to
ground.
8. On Reconnect connector Sleeper Go to next step.
(162). Does heater box control
damper door function circuits
properly? check
good.
9. Off/ Open top of heater box. (N/L), 75L 12 ± 1.5 Go to Locate cause of low
On Disconnect heater box to ground. volts. next or no voltage in circuit
damper connector (N/L) step. 75L, then repair.
and with key switch in
ignition position, measure
voltage from circuit 75L
to ground.
10. On At heater box damper (N/L), 75L 12 ± 1.5 Go to Locate open or poor
connector (N/L) measure to 75-GL. volts. next connection in circuit
voltage from circuit 75L step. 75-GL, connector
to 75-GL. (161), circuit 75-G
or 11-G to right dash
panel ground stud,
then repair.
11. On At heater box damper (N/L), 75K Approx. Go to Locate cause of low
connector (N/L), measure to ground. 2V and next or no voltage in circuit
voltage from circuit 75K 11V. step. 75K, then repair.
to ground while rotating
sleeper temperature
control fully CCW and
CW.

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 14 HEATER AND AIR CONDITIONER 587

Table 170 Heater-Bunk With Standard Temperature Control (cont.)

STEP KEY ACTION TEST SPEC. YES- IN NO-OUT OF SPEC.
POINTS SPEC.
12. Off/ Reconnect heater box Go to Replace defective
On damper connector (N/L), next damper motor
move key switch to step. assembly.
ignition position and note
if damper door closes
completely and opens
completely, when the
sleeper temperature
control is moved fully CW
and CCW.
13. Off Sleeper temperature
control circuits check
good.

3.8. HEATER-BUNK WITH THERMOSTAT TEMPERATURE CONTROL

Table 171 Heater-Bunk With Thermostat Temperature Control
STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
1. Off/ Disconnect connector (592), 12 ± 1.5 Go to Locate cause of low
On (592). Move key switch terminal A volts. next or no voltage in circuit
to ignition position and to ground. step. 75AL, then repair.
move bunk heater blower
switch to low. At harness
connector, measure
voltage from terminal A to
ground.
2. On At harness connector (592), 12 ± 1.5 Go to Locate open or poor
(592) measure voltage terminal A volts. next connection in circuit
from terminal A to C. to C. step. 75-GS, 11–GAE to
sleeper ground stud
(746) or 11-GAN to
B-pillar ground stud,
then repair.
3. Off Disconnect connector (592), <1 ohm. Go to Locate open in circuit
(162). Measure terminal next 75K, then repair.
resistance from (592) B to (162) step.
terminal B to (162) terminal B.
terminal B.
4. Off Reconnect connector (592), Approx. Go to Locate open or short
(162). Measure terminal B 8K ohms. next in circuit 75K or the
resistance from (592) to ground. step. flat pack, then repair.
terminal B to ground.

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588 14 HEATER AND AIR CONDITIONER

Table 171 Heater-Bunk With Thermostat Temperature Control (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
5. On Reconnect connector (905), Full CCW: Go to Replace defective
(592). Disconnect terminal A A higher next automatic temperature
sleeper A/C ON/OFF to C. voltage. step. control module.
switch (905). At harness Full CW:
to connector (905), A lower
measure voltage between voltage.
pins A and C while turning
control knob full CCW,
then fully CW.
6. On Set control knob to center (905), Varying Go to Replace defective
of range. At connector terminal A voltage. next automatic temperature
to switch (905), measure to C. step. control module.
voltage between pins
A and C. Does output
voltage change as warm
or cool air is applied to
the ambient air sensor?
7. Off/ Re-install switch (905). (162) 12 ± 1.5 Go to Locate cause of low
On Move key switch terminal A volts. next or no voltage in circuit
to ignition position. to ground. step. 75L, then repair.
Measure voltage from
(162) terminal A to
ground.
8. On Reconnect connector Sleeper Go to next step.
(162). Does heater box control
damper door function circuits
properly? check
good.
9. Off/ Open top of heater box. (N/L), 75L 12 ± 1.5 Go to Locate cause of low
On Disconnect heater box to ground. volts. next or no voltage in circuit
damper connector (N/L) step. 75L, then repair.
and with key switch in
ignition position, measure
voltage from circuit 75L
to ground.
10. On At heater box damper (N/L), 75L 12 ± 1.5 Go to Locate open or poor
connector (N/L), measure to 75-GL. volts. next connection in circuit
voltage from circuit 75L step. 75-GL, connector
to 75-GL. (161), circuit 75-G
or 11-G to right dash
panel ground stud,
then repair.

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 14 HEATER AND AIR CONDITIONER 589

Table 171 Heater-Bunk With Thermostat Temperature Control (cont.)

STEP KEY ACTION TEST SPEC. YES-IN NO-OUT OF SPEC.
POINTS SPEC.
11. On At heater box damper (N/L), 75K Approx. Go to Locate cause of low
connector (N/L), measure to ground. 2V and next or no voltage in circuit
voltage from circuit 75K 11V. step. 75K, then repair.
to ground while rotating
sleeper temperature
control fully CCW and
CW.
12. Off/ Reconnect heater box Go to Replace defective
On damper connector (N/L), next damper motor
move key switch to step. assembly.
ignition position and note
if damper door closes
completely and opens
completely, when the
sleeper temperature
control is moved fully CW
and CCW.
13. Off Sleeper temperature
control circuits check
good.

4. COMPONENT LOCATIONS
(B1) Battery Stud. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . . Power Distribution Panel
(B2) Battery Stud. . . . . .. . . . .. . . . . .. . . . .. . . . . .. . . . .. . . . .. . . . . . Power Distribution Panel
J7 Junction Point/Ground Stud. . . . . . . . . . . . . . . . . . . . . .. . . . . . At Dash Panel Left Side
(1) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Left Side of Engine Cowl
(2) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Above Connector 3
(3) Dash Panel Connector. . .. .. . .. . .. .. . .. .. . .. .. . .. .. . . . . . Right Side of Engine Cowl, Below Connector 2
(27) Heater Resistor & Thermofuse. . . . . . . . . . . . . . . . .. . . . . . In Heater Box
(28) Heater Resistor & Thermofuse/Box Sleeper
. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . . .. . . . . . .. . . . . . .. . . . . . In Heater Box
(40) Key Switch.. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. . .. .. . .. .. . . . . . Instrument Panel to Left of Steering Column.
(43) Truck Body/Trailer Feed . .. . . . . . . . . . .. . . . . . . . . . .. . . . . . Left Rear of Cab, "B" Pillar
(48) Sleeper Blower Motor Connector/Pro
Sleeper.. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . .. . . . . . At “B”– Pillar, Right Side
(147) Auxiliary Bunk Blower Relay/Pro Sleeper . . . . . . . . . Power Distribution Panel
(147) Heater Control Motor #2/Box Sleeper. . . . . . . .. . . . . . Power Distribution Panel
(161) Heater Box Connector. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Pigtail at Right Front of Cab
(162) Heater Box Connector. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Pigtail at Right Front of Cab
(196) Resistor and Thermofuse Assembly/Pro
Sleeper.. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .. . . . . .. . . . . . Inside Blower Assembly
(227) Fan Solenoid.. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .. .. . . . . . At Front of Engine
(228) A/C High Pressure Switch/Pro Sleeper. . . . . .. . . . . . At A/C Compressor, on Engine
(454) G2 Ground Adapter. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Instrument Panel
(462) R2 High Speed Fan #1 Relay. . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(462) R3 High Speed Fan #2 Relay. . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel

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(462) R5 Heater Control. . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . Power Distribution Panel

(462) R6 Air Conditioning. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Power Distribution Panel
(462) Fuse Block/Relay Socket 1. . .. . . .. . .. . . .. . . .. .. . . . . . At Power Distribution Center Above Engine Tunnel
(462) Fuse Block/Relay Socket 2. . .. . . .. . .. . . .. . . .. .. . . . . . At Power Distribution Center Above Engine Tunnel
(462) Fuse Block/Relay Socket 3. . .. . . .. . .. . . .. . . .. .. . . . . . At Power Distribution Center Above Engine Tunnel
(462) Fuse Block/Relay Socket 5. . .. . . .. . .. . . .. . . .. .. . . . . . At Power Distribution Center Above Engine Tunnel
(462) Fuse Block/Relay Socket 6. . .. . . .. . .. . . .. . . .. .. . . . . . At Power Distribution Center Above Engine Tunnel
(494)Ignition Adapter (I1). . .. . . . .. . . . .. . . .. . . . .. . . . .. .. . . . . . Behind Fuse Panel
(495) Ignition Adapter (I2). . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Located Behind Instrument Panel — Center
(499) A1 Accessory Adapter. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Fuse Panel Right Side
(582) Sleeper Fuse Block/Pro Sleeper. . .. . . .. . . . .. .. . . . . . In Left Luggage Compartment
(583) Sleeper Fuse Block/Pro Sleeper. . .. . . .. . . . .. .. . . . . . In Left Luggage Compartment
(584 )Sleeper High Speed Relay/Pro Sleeper. . . . .. . . . . . At Power Distribution Center, Above Engine Tunnel
(585) Sleeper Medium Speed Relay/Pro
Sleeper. . . .. . . . . . .. . . . . . .. . . . . .. . . . . . .. . . . . . .. . . . . . .. . . .. . . . . . At Power Distribution Center, Above Engine Tunnel
(592) Temperature Switch/Pro Sleeper. . . . . . . . . . . . .. . . . . . At Temperature Control Panel
(593) Heater Blower Control/Pro Sleeper. .. . .. .. . ... . . . . . At Temperature Control Panel
(594) Dome Light Switch/Pro Sleeper.. . .. .. .. .. .. ... . . . . . At Temperature Control Panel
(612) Refrigerator (Inline)/Pro Sleeper. . . . . . . . . . . . . .. . . . . . Floor of Sleeper at Wall Between Cab and Left
Luggage Compartment
(642) Sleeper to Roof Connector/Pro Sleeper. . . . .. . . . . . At Lower Left Front Corner of Sleeper Box
(643) Sleeper to Roof Connector/Pro Sleeper. . . . .. . . . . . At Lower Left Front Corner of Sleeper Box
(904) A/C Switch On/Off/Pro Sleeper. . . . . . . . . . . . . . .. . . . . . Located Behind Bunk Control Panel
(905) Sleeper A/C On/Off Switch/Pro Sleeper. . . . .. . . . . . Behind Sleeper Control Panel
(906) Cab to Sleeper #1. . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . Behind Driver Under Floor (B-Pillar)
(942) Cab to Sleeper #2. . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . Behind Driver Under Floor (B-Pillar)
(1056) Blower Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . In Instrument Panel
(1057) HVAC Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . In Instrument Panel
(1058) Air Distribution Motor. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Behind Gauge Cluster Panel
(1059) Recirculation Motor. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Beneath Passenger Kick Panel
(1060) Heater Connector #3. . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . Pigtail at Right Front of Cab
(N/L) Low Pressure Safety Switch. . . .. . .. . .. . . .. . .. .. . . . . . Under Heater Box
(N/L) High Pressure Safety Switch. . . . . . . . . . . . . . . . . .. . . . . . Under Heater Box
(N/L) A/C Compressor Clutch. . . . . .. . . . . . .. . . . . . .. . . .. . . . . . (Inline) At Black Wire to Clutch
(N/L) Cab Stepper Motor. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . In Heater Box
(N/L) Bunk Stepper Motor. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . In Heater Box
(N/L) Right Dash Panel Ground Stud. . . . . . . . . . . . . . .. . . . . . Under Dash Panel at Right Side of Cab

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 14 HEATER AND AIR CONDITIONER 591

Figure 186 Cab Heater And Air Conditioner Wiring (Dash Panel)
1. WIRING TO REAR OF CAB OR PRO SLEEPER
2. CIRCUIT 11-GB
3. CIRCUIT 11-G
4. NO BUS BAR WITH 3+1 BATTERY SYSTEM
5. TO HEATER
6. (3) ENGINE HARNESS CONNECTOR
7. (2) CHASSIS HARNESS CONNECTOR
8. RIGHT HAND DASH GROUND STUD
9. FUSE BLOCK GROUND STUD
10. (B2) BATTERY STUD
11. (B1) BATTERY STUD
12. KEY SWITCH
13. LEFT HAND DASH GROUND STUD
14. (1) FRONT END HARNESS CONNECTOR

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592 14 HEATER AND AIR CONDITIONER

Figure 187 Cab Heater And Air Conditioner Wiring

1. TO DASH PANEL
2. FRESH AIR INLET
3. HVAC UNIT
4. HVAC HARNESS
5. TREATED AIR DUCT
6. CONNECTORS (161), (162) AND (1060)

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 14 HEATER AND AIR CONDITIONER 593

Figure 188 Cab Heater And Air Conditioner Wiring (Pro Sleeper)
1. TO WIRING AT DASH
2. SLEEPER BOX HARNESS
3. SLEEPER CONNECTOR #1 (906)

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Figure 189 Cab Heater and Air Conditioner Wiring

1. HVAC CONTROL CONNECTOR (1057)
2. BLOWER CONTROL CONNECTOR (1056)
3. HVAC CONTROL
4. MAIN CAB HARNESS

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 14 HEATER AND AIR CONDITIONER 595

Figure 190 Cab Wiring Megafuse

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596 14 HEATER AND AIR CONDITIONER

1. 150A MEGAFUSE
2. CIRCUIT 14A TO (B1), (B2) BATTERY STUDS
3. CIRCUIT 14
4. STARTER MAGNETIC SWITCH
5. CIRCUIT 2
6. CIRCUIT 17C
7. CIRCUIT 17B
8. CIRCUIT 14A

Figure 191 Typical Engine Wiring to Air Conditioner Compressor (Caterpillar 3406E Shown)
1. (190) ELECTRONIC ENGINE CONNECTOR
2. (3) CHASSIS HARNESS CONNECTOR
3. (2) CAB/ENGINE HARNESS CONNECTOR
4. RIGHT HAND DASH PANEL GROUND STUD
5. TO ENGINE HARNESS

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 14 HEATER AND AIR CONDITIONER 597

Figure 192 Typical Engine Wiring to Air Conditioner Compressor (Caterpillar 3406E Shown)
1. AIR CONDITIONING COMPRESSOR
2. ENGINE HARNESS TO DASH WIRING

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598 14 HEATER AND AIR CONDITIONER

Figure 193 Typical Engine Wiring To A/C Compressor (Caterpillar 3406E Shown)
1. CIRCUIT 77C
2. ALTERNATOR
3. ENGINE HARNESS
4. INLINE CONNECTOR
5. AIR CONDITIONER HIGH PRESSURE SWITCH (228)

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 14 HEATER AND AIR CONDITIONER 599

Figure 194 Pro Sleeper and SkyRise Sleeper Wiring

1. SLEEPER WIRING TO LEFT SIDE OF SLEEPER
2. SLEEPER HVAC CONTROL PANEL
3. SLEEPER CONNECTOR #1 (906)
4. SLEEPER CONNECTOR #2 (942)

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600 14 HEATER AND AIR CONDITIONER

Figure 195 Pro Sleeper and SkyRise Sleeper Wiring

1. SLEEPER BLOWER MOTOR
2. SLEEPER WIRING HARNESS TO RIGHT SIDE OF SLEEPER
3. SLEEPER BLOWER MOTOR
4. CIRCUIT 75AC
5. CONNECTOR (48)
6. SLEEPER HARNESS TO BLOWER MOTOR

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 14 HEATER AND AIR CONDITIONER 601

Figure 196 Sleeper Wiring, Fuse and Relay Locations

1. 5 AMP REFRIGERATOR FUSE
2. 10 AMP AUXILIARY BLOWER FUSE
3. 20 AMP TV FUSE
4. MAIN SLEEPER HARNESS
5. MEDIUM SPEED RELAY
6. HIGH SPEED RELAY
7. LABEL

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602 14 HEATER AND AIR CONDITIONER

Figure 197 Pro Sleeper Standard Temperature Control

1. SLEEPER CONTROL PANEL
2. CONNECTOR (593) BUNK HEATER BLOWER SWITCH
3. SLEEPER TEMPERATURE CONTROL
4. CONNECTOR (592)
5. SLEEPER HARNESS

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 14 HEATER AND AIR CONDITIONER 603

Figure 198 Pro Sleeper Thermostat Temperature Control

1. SLEEPER CONTROL PANEL
2. CONNECTOR (593) BUNK HEATER BLOWER SWITCH
3. SLEEPER TEMPERATURE CONTROL
4. CONNECTOR (592)
5. SLEEPER HARNESS

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Printed in the United States of America