6/11/24, 8:29 p.m. SIS 2.
2022/06/17 Engine Speed/Timing Sensor Circuit - Test (SENR9617-06)
SMCS - 1439, 1912 i09548595
System Operation Description:
PIP
-
Use this procedure to troubleshoot any suspect problems with the following sensors:
Primary engine speed/timing sensor 202 1082
01: 4 / 1 9 673
Secondary engine speed/timing sensor
2 1 / 0
SEN :53- 7
9
This procedure covers the following diagnostic codes:
© 2 R961 05:00
190-02 Loss of Engine Speed Signal
024 7
190-11 Engine Speed Sensor mechanical failure
Cat
342-02 Loss of Secondary Engine Speed signal
erp
342-11 Secondary Engine Speed Sensor mechanical failure
illa
rI
The engine uses two engine speed/timing sensors. The primary engine speed/timing sensor and
the secondary engine speed/timing sensor are used to detect the reference for engine speed
nc.
and for engine timing from a unique pattern in the timing reference ring. The timing reference
ring is located on the back of the camshaft gear. To determine rpm, the Electronic Control
Module (ECM) counts the time between pulses that is created by the sensor as the gear rotates.
Under normal operation, the secondary engine speed/timing sensor is used to determine timing
for starting purposes. The secondary engine speed/timing sensor is used to determine when the
piston in the No. 1 cylinder is at the top of the compression stroke. When the timing has been
established, the primary engine speed/timing sensor is then used to monitor engine speed.
When the timing has been established, the ECM triggers each injector in the correct firing order
at the correct time. The actual timing and duration of each injection is based on engine rpm and
on load.
If the engine is running and the signal from one sensor is lost, no change in engine performance
will be noticed. If the engine is running and the signals from both sensors are lost, fuel injection
will be terminated and the engine will be shut down by the ECM.
The engine will start when only one sensor signal is present. The engine will not start if the
signals from both sensors are lost.
Both sensors are magnetic sensors. The two sensors are not interchangeable.
If a replacement of the ECM is required, the ECM parameters and the timing calibration can be
transferred from the suspect ECM to the replacement ECM. This feature requires the Caterpillar
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 1/10
6/11/24, 8:29 p.m. SIS 2.0
Electronic Technician (ET) and this feature is only possible if the existing ECM can communicate
with Cat ET. Use the "Copy Configuration - ECM Replacement" feature on Cat ET.
Complete all of the following tasks when you install a speed/timing sensor:
Ensure that an O-ring is installed on the sensor. If the O-ring is damaged or missing, replace
the O-ring.
Lubricate the O-ring with oil.
Ensure that the sensor is fully seated into the engine before tightening the bracket bolt.
Ensure that the electrical connector is latched.
Ensure that the harness is properly secured, and ensure that each tie-wrap is placed in the
correct location.
Illustration 1 g07486231
Schematic for the engine speed/timing sensors
Test Step 1. CHECK FOR DIAGNOSTIC CODES
A. Connect Cat ET to the service tool connector. Refer to Troubleshooting, "Electronic Service
Tools".
B. Restore electrical power to the engine ECM.
C. Start the engine and run the engine until the engine is at the normal operating temperature.
Note: If the engine will not start, monitor the engine rpm on Cat ET while the engine is being
cranked. Cat ET may need to be powered from another battery while the engine is being
cranked.
D. Wait at least 30 seconds for activation of the diagnostic codes. Look for these codes on Cat
ET:
190-02
190-11
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 2/10
6/11/24, 8:29 p.m. SIS 2.0
342-02
342-11
Expected Result:
One or both of the diagnostic codes that are listed above are logged or active.
Note: If the engine will not start and Cat ET displayed 0 rpm during cranking, select "No Engine
rpm".
Results:
No Engine rpm - Engine rpm is not indicated on Cat ET. Proceed to Test Step 2.
Active or logged code - There is an active diagnostic code or a logged diagnostic code for
an engine speed/timing sensor. Proceed to Test Step 4.
No codes - Neither code is active or logged.
Repair: Refer to the appropriate symptoms in Troubleshooting, "Troubleshooting Without a
Diagnostic Code".
STOP
Test Step 2. CHECK THE INSTALLATION OF THE SENSOR ASSEMBLY
A. Remove electrical power from the engine ECM.
Illustration 2 g01180490
Left side view
(1) Engine
(2) Mounting flange
(3) Bracket
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 3/10
6/11/24, 8:29 p.m. SIS 2.0
B. Visually inspect the sensor assembly without removing the sensor assembly from the
engine. Flanges (2) must be flush against engine (1) in order to ensure proper operation.
Inspect bracket (3). Verify that the bracket securely holds the flanges of the sensors flush
against the engine.
Verify that the bracket is not bent. If the bracket is bent or if an obstruction is preventing the
sensor assembly from being installed correctly, the engine will not start.
Note: The bracket cannot be replaced separately.
C. Remove the sensor assembly from the engine.
Illustration 3 g01180501
Exploded view of the engine speed/timing sensors
(4) O-ring seals
D. Ensure that one O-ring (4) is installed on each sensor. Check the O-rings for damage.
Replace the O-rings, if necessary.
Results:
OK - The sensor assembly's components are OK.
Repair: Perform the following procedure in order to properly install the sensor assembly:
1. Lubricate each O-ring with engine oil.
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 4/10
6/11/24, 8:29 p.m. SIS 2.0
2. Fully seat the sensor assembly in the engine.
Note: If the sensor assembly will not fully seat into the engine, replace the sensor
assembly.
3. Tighten the bracket bolt.
4. Connect the sensor's electrical connectors. Verify that the connectors are latched on
both sides.
5. Ensure that the harness is properly secured, and that the tie-wraps are placed in the
correct location.
Proceed to Test Step 3.
Not OK - At least one of the sensor assembly's components is not OK.
Repair: Obtain a new sensor assembly. Perform the following procedure in order to properly
install the sensor assembly:
1. Lubricate each O-ring with engine oil.
2. Fully seat the sensor assembly in the engine.
Note: If the sensor assembly will not fully seat into the engine, replace the sensor
assembly.
3. Tighten the bracket bolt.
4. Connect the sensor's electrical connectors. Verify that the connectors are latched on
both sides.
5. Ensure that the harness is properly secured, and that the tie-wraps are placed in the
correct location.
Verify that the problem is resolved.
STOP
Test Step 3. INSPECT THE ELECTRICAL CONNECTORS AND THE WIRING
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 5/10
6/11/24, 8:29 p.m. SIS 2.0
Illustration 4 g01181799
Left side engine view (typical example)
(5) J401/P401 connector for the primary engine speed/timing sensor
(6) J402/P402 connector for the secondary engine speed/timing sensor
(7) J2/P2 ECM connector
A. Thoroughly inspect connectors (5), (6), and (7). Refer to Troubleshooting, "Electrical
Connectors - Inspect".
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 6/10
6/11/24, 8:29 p.m. SIS 2.0
Illustration 5 g01181800
Left side view
(P2-48) Primary engine speed/timing sensor +
(P2-49) Primary engine speed/timing sensor -
(P2-58) Secondary engine speed/timing sensor +
(P2-59) Secondary engine speed/timing sensor -
B. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the engine
speed/timing sensors.
C. Check the allen head screw on each ECM connector for the proper torque. Refer to
Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 7/10
6/11/24, 8:29 p.m. SIS 2.0
D. Check the harness and the wiring for abrasion and for pinch points from each sensor back
to the ECM.
Expected Result:
All of the connectors, pins and sockets are completely coupled and/or inserted and the harness
and wiring are free of corrosion, of abrasion and of pinch points.
Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 4.
Not OK - The connectors and/or wiring are not OK.
Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Ensure that all
of the seals are properly in place and ensure that the connectors are completely coupled.
Verify that the repair eliminates the problem.
STOP
Test Step 4. MEASURE THE SENSOR RESISTANCE THROUGH THE ENGINE HARNESS
A. Disconnect the J2/P2 ECM connector.
B. If you are troubleshooting a problem with the primary engine speed/timing sensor, perform
the following procedure:
a. Measure the sensor's resistance between P2-48 (primary engine speed/timing +) and
P2-49 (primary engine speed/timing -).
b. Check for an intermittent open circuit or for a short circuit by moving the harness while
you take the resistance measurement. Pull the wires that are directly behind the sensor
or shake the wires that are directly behind the sensor.
Resistance ... 75 to 230 Ohms
C. If you are troubleshooting a problem with the secondary engine speed/timing sensor,
perform the following procedure:
a. Measure the sensor's resistance between P2-58 (secondary engine speed/timing +)
and P2-59 (secondary engine speed/timing -).
b. Check for an intermittent open circuit or for a short circuit by moving the harness while
you take the resistance measurement. Pull the wires that are directly behind the sensor
or shake the wires that are directly behind the sensor.
Resistance ... 600 to 1800 Ohms
Expected Result:
The resistance measurement is within the specifications.
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 8/10
6/11/24, 8:29 p.m. SIS 2.0
Results:
OK - The resistance measurement is within the specifications.
Repair: The sensors and the harness are OK. Replace the ECM. Refer to Troubleshooting,
"Replacing the ECM" for detailed instructions.
STOP
Not OK - The readings are not within the specifications. The sensor resistance is not within
the acceptable range when the sensor resistance is measured through the engine harness.
Proceed to Test Step 5.
Test Step 5. MEASURE THE RESISTANCE OF THE SENSOR
A. Disconnect the harness connector for the suspect sensor.
B. Thoroughly inspect the sensor's connectors. Refer to Troubleshooting, "Electrical
Connectors - Inspect".
C. Measure the sensor's resistance between terminals A and B.
Expected Result:
For the primary engine speed/timing sensor, the resistance measurement is between 75 and 230
Ohms. For the secondary engine speed/timing sensor, the resistance measurement is between
600 and 1800 Ohms.
Results:
OK - The reading is within the specification. There is a problem with the wiring between the
engine speed/timing sensor and the ECM. There may be a problem with a connector.
Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Verify that the
problem is resolved.
STOP
Not OK - The reading is not within the specification. There is an electrical problem with the
engine speed/timing sensor.
Repair: Perform the following procedure in order to check and install the new sensor
assembly:
1. Before you install the new sensor assembly, measure the resistance of the new
sensors.
If the resistance measurements of the new sensors are within the specifications, install
the new sensor assembly in the engine according to the following procedure:
a. Loosen the bolt and remove the bolt that holds the sensor to the engine.
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 9/10
6/11/24, 8:29 p.m. SIS 2.0
b. Ensure that an O-ring is installed on the new sensor assembly. Verify that the O-
ring is free of damage.
c. Seat the sensor and tighten the bolt.
If the sensor will not seat, replace the sensor.
d. Ensure that the harness is secured in the proper location.
2. Verify that the repair eliminates the problem.
STOP
PIP-10829673
2024/11/07
01:29:16-05:00
i01506570
© 2024 Caterpillar Inc.
https://sis2.cat.com/#/print-preview/service/50a38977-430d-4180-adc3-700d1a761937 10/10
