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Technical Service Information
THM 4T65E
INTERNAL MODE SWITCH ADDED IN SOME MODELS
AND "CORRECT" ASSEMBLY IN CASE
CHANGE: Beginning at the start of production for 1999, some models of the THM 4T65E were produced
with an "Internal Mode Switch" (IMS). The transaxle Internal Mode Switch (IMS) is a sliding
contact switch attached to the selector detent inside the transmission side cover, as shown in
Figure 1. The four inputs to the PCM from the IMS indicate which position is selected by the
transmission selector lever. This information is used for ignition timing, EVAP canister purge,
EGR and IAC valve operation, as well as for starting functions when the selector lever is in P or N
and proper ground is made. The state of each input is available for display on the scan tool. The
four input parameters represented are Mode P, Mode A, Mode B and Mode C (Refer to Figure 2).
REASON: Mounted internally for increased protection from the elements and engine compartment heat, for
increased durability and reliability. This also eliminates the need for adjustments at the vehicle
assembly plants.
PARTS AFFECTED:
(1) MODE SWITCH - Now mounted internally instead of externally on the transaxle case, and
applies to only some models (See Figure 1).
(2) INTERNAL WIRE HARNESS - Five wires added to the internal harness to accommodate the
new mode switch that now run through the transaxle case connector (See Figure 2).
DIAGNOSIS PROCEDURES:
(1) The new Internal Mode Switch fault can generate the following Diagnostic Trouble Codes:
P1819 - Internal Mode Switch, No Start/W
rong Range
P1820 - Internal Mode Switch, Circuit "A" Low
P1822 - Internal Mode Switch, Circuit "B" High
P1825 - Internal Mode Switch, Invalid Range
P1826 - Internal Mode Switch, Circuit "C" High
Note: None of the above DTC's will illuminate the Malfunction Indicator Lamp (MIL).
(2) Refer to Figure 2 for Internal Mode Switch (IMS) connector terminal identification, wire
colors and circuit functions.
(3) Refer to Figure 3 for a complete wiring schematic from the transaxle through the transaxle
case connector and on to the Powertrain Control Module (PCM). This includes wire colors
both inside and outside and terminal identification of transaxle components.
Continued on next Page.
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Technical Service Information
(4) Refer to Figure 4 for identification of the transaxle case connector terminals that were added to
accommodate the new IMS, and the wire colors and functions. We have also included a
resistance chart for the internal transaxle components.
(5) Refer to Figure 5 for identification of the PCM connector terminals, both Blue and the Clear
connectors for the transaxle related components.
(6) Refer to Figure 6 for an Internal Mode Switch Logic chart that will provide you with the proper
readings for all four input parameters for the IMS. These can be viewed from the appropriate
scan tool.
(7) Figure 7 provides you with the information to bench check the Internal Mode Switch for the
proper continuity at the Internal Mode Switch connector, and Figure 8 provides you the same
information to check the switch at the transaxle case connector terminals.
INSTALLATION PROCEDURES:
The new Internal Mode Switch also allows you to make an assembly error on the installation.
Refer to Figure 9 for the most common "Incorrect" assembly and the "Correct" assembly of
the Internal Mode Switch.
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Technical Service Information
THM 4T65E
INTERNAL MODE SWITCH LOCATION
5 6 7 8
G
A
B
C
P
4
1
3 2
1. OUTPUT SPEED SENSOR 5. PRESSURE CONTROL SOLENOID
2. TRANSMISSION FLUID PRESSURE SWITCH ASSEMBLY 6. 1-2/3-4 SHIFT SOLENOID
3. TRANSMISSION FLUID TEMPERATURE SENSOR 7. INPUT SPEED SENSOR
4. TCC PWM SOLENOID 8. 2-3 SHIFT SOLENOID
9. INTERNAL MODE SWITCH
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Figure 1
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INTERNAL MODE SWITCH CONNECTOR
TERMINAL IDENTIFICATION
Internal Mode
Switch
Black/White
F K
P
R
INTERNAL MODE SWITCH (IMS)
N
Red/Black
F
D
E CONNECTOR
3
PIN WIRE COLOR CIRCUIT NO. FUNCTION
2
1
P
A NOT USED
R
N
Dk Green/White
G B GRAY/WHT 776 IMS MODE P
D
D
3
C YEL/BLK 773 IMS MODE C
2
D DK GRN/WHT 772 IMS MODE B
P
R
N
Yellow/Black E RED/BLK 771 IMS MODE A
H
D
C
F BLK/WHT 1050 GROUND
3
2
1
P
R
N
Gray/White
J
D
B
3
2
View Looking At Wire
Side Of IMS Connector
A B C D E F
Black/White
Red/Black
Dk Green/White
Yellow/Black
Gray/White
G
A
B
C
P
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Figure 2
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TRANSAXLE WIRE SCHEMATIC
1-2 Shift
Solenoid Lt. Green Lt. Green
A
Lt. Green
C1-04
Yellow/Blk C1 = Blue
2-3 Shift C1-44 Connector
Solenoid Yellow Yellow/Blk Red/Blk
B C2-45 C2 = Clear
Blue/Wht Connector
C2-46
Brown
C2-78
EPC
Solenoid Purple Red/Blk
C
Lt. Blue Blue/Wht Battery
D Feed
TCC/PWM
Solenoid Brown Brown
T OXY SENSOR
FUSE 20A
Red Pink HOT IN ON Red
E OR START C1-20
Black/White Black/White
F K SPLICE
108
P
R
N
Red/Blk Black/White
F
D
E Ground
3
101 Powertrain
2
Control
P
R
Black/White
N
Dk Grn/Wht Yellow Module
G
D
Internal Mode D
(PCM)
3
Switch
2
1
P
R
Blk/Wht
N
Yel/Blk Gray C1-56
H
D
C PCM Blk/Wht
C1-57
3
Grounds
2
Blk/Wht
1
C1-60
P
R
N
Gry/Wht White
J
D
B
3
2
Black/White
C2-18
Black Red/Blk Yellow
Input Shaft S Gray
C1-68
Speed Sensor C2-56
Dk. Green Blue/Wht White
V C2-16
Red/Blk
C1-63
Pressure Switch Assembly Blue/Wht
C1-62 C1 = Blue
(Manual Valve)
Pink Connector
Reverse C1-22
Switch
Pink Pink Yellow
N C2-63 C2 = Clear
TCC Release
Switch Dk. Blue Connector
White Yellow C2-57
U Red
C2-17
P,R,N,D4,D3 P,R,N,D4
Yellow/Blk
Switch Switch
Dk. Blue Dk. Blue C2-68
R Black
C2-35
D4, D3
Switch
Orange Red
P
Transaxle Fluid
Temp Sensor Brown Yellow/Blk
L
Gray Black
M
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Figure 3 04-31
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TRANSAXLE CASE CONNECTOR PIN IDENTIFICATION
AND RESISTANCE CHART
Ohms Resistance Chart
Resistance Resistance
Cavities Component @ 68°F @ 190°F
A B C D D C B A
A-E 1-2 Shift Solenoid 19-24Ω 24-31Ω
E F G H J K B-E 2-3 Shift Solenoid 19-24Ω 24-31Ω K J H G F E
L M N P R S T-E TCC/PWM Solenoid 10-12Ω13-15Ω S R P N M L
C-D EPC Solenoid 3-5Ω 5-6Ω
S-V Input Speed Sensor 893-1127Ω
1132-1428Ω
T U V V U T
M-L TFT Sensor 3164-3867Ω225-285Ω
Output Speed Sensor 981-1864Ω
View Looking Into View Looking Into
Transaxle Case Connector Vehicle Harness Connector
Copyright © 2004 ATSG
CASE CONNECTOR PIN FUNCTION
Pin External Wire Color Function
A Light Green Ground signal from PCM for the 1-2 Shift Solenoid (A)
B Yellow/Black Ground signal from PCM for the 2-3 Shift Solenoid (B)
C Red/Black Electronic Pressure Control Solenoid, HIGH Control
D Blue/White Electronic Pressure Control Solenoid, LOW Control
E Pink Transaxle Solenoid 12V Power In
F Black/White Internal Mode Switch Range Signal "A"
G Yellow Internal Mode Switch Range Signal "B"
H Gray Internal Mode Switch Range Signal "C"
J White Internal Mode Switch Range Signal "P"
K Black/White Internal Mode Switch ground
L Yellow/Black Transaxle Fluid Temperature (TFT) Sensor HIGH
M Black Transaxle Fluid Temperature (TFT) Sensor LOW
N Pink Pressure Switch Assembly, Range Signal "A"
P Red Pressure Switch Assembly, Range Signal "C"
R Dark Blue Pressure Switch Assembly, Range Signal "B"
S Red/Black Input Speed Sensor (ISS) signal HIGH
T Brown Ground signal from PCM for the TCC/PWM Converter Clutch Solenoid
U Yellow TCC Release Switch signal to the PCM
V Blue/White Input Speed Sensor (ISS) signal LOW Copyright © 2004 ATSG
Figure 4
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C1 "BLUE" PCM CONNECTOR
41 60 61 80
1 20 21 40
Pin No. Wire Color Circuit Description
4 Lt Green 1222 Shift Solenoid "A" Ground Signal
20 Red 1642 Battery Feed
22 Pink 1224 Transaxle Fluid Pressure Switch "A" Input
44 Yellow/Black 1223 Shift Solenoid "B" Ground Signal
56 Black/White 451 PCM Ground
57 Black/White 451 PCM Ground
60 Black/White 451 PCM Ground
62 Dk Blue/White 1231 Input Shaft Speed Sensor, Low
63 Red/Black 1230 Input Shaft Speed Sensor, High
68 Yellow 772 Internal Mode Switch Signal "B"
C2 "WHITE" PCM CONNECTOR
41 60 61 80
1 20 21 40
Pin No. Wire Color Circuit Description
16 White 776 Internal Mode Switch Signal "P"
17 Red 1225 Transaxle Fluid Pressure Switch "C" Input
18 Black/White 771 Internal Mode Switch Signal "A"
35 Black 808 Transaxle Fluid Temperature Sensor Ground
45 Red/Black 1228 Pressure Control Solenoid, High
46 Lt Blue/White 1229 Pressure Control Solenoid, Low
56 Gray 773 Internal Mode Switch Signal "C"
57 Dk Blue 1225 Transaxle Fluid Pressure Switch "B" Input
63 Yellow 657 TCC Release Switch
68 Yellow/Black 1227 Transaxle Fluid Temperature Sensor
78 Brown 418 TCC PWM Solenoid Control
Copyright © 2004 ATSG
Figure 5
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INTERNAL MODE SWITCH LOGIC
SCAN TOOL IMS RANGE
GEAR SELECTOR POSITION A B C P
PARK LOW HI HI LOW
PARK/REVERSE LOW LOW HI LOW
REVERSE LOW LOW HI HI
REVERSE/NEUTRAL HI LOW HI HI
NEUTRAL HI LOW HI LOW
NEUTRAL/DRIVE 4 HI LOW LOW LOW
DRIVE 4 HI LOW LOW HI
DRIVE 4/DRIVE 3 LOW LOW LOW HI
DRIVE 3 LOW LOW LOW LOW
DRIVE 3/DRIVE 2 LOW HI LOW LOW
DRIVE 2 LOW HI LOW HI
DRIVE 2/DRIVE 1 HI HI LOW HI
DRIVE 1 HI HI LOW LOW
HI HI HI HI
ILLEGAL RANGES LOW HI HI HI
HI HI HI LOW
HI = Ignition Voltage
LOW = 0 Voltage Copyright © 2004 ATSG
Figure 6
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INTERNAL MODE SWITCH CONTINUITY CHECKS AT IMS CONNECTOR
MANUAL SHIFT DETENT LEVER POSITION
IMS TERMINALS
P P/R R R/N N N/D4 D4 D4/D3 D3 D3/D2 D2 D2/D1 D1
F to B C C O O C C O O C C O O C
F to C O O O O O C C C C C C C C
F to D O C C C C C C C C O O O O
F to E C C C O O O O C C C C O O
E to B C C O O O O O O C C O O O
E to C O O O O O O O C C C C O O
E to D O C C O O O O C C O O O O
D to B O C O O C C O O C O O O O
D to C O O O O O C C C C O O O O
C to B O O O O O C O O C C O O C
C = CLOSED CIRCUIT
O = OPEN CIRCUIT SPECIAL NOTE:
Terminals B, C, D, E, and F must indicate an "OPEN" circuit when
checked against the Internal Mode Switch shaft, through all ranges.
Copyright © 2004 ATSG
Figure 7
INTERNAL MODE SWITCH CONTINUITY CHECKS AT CASE CONNECTOR
CASE CONNECTOR MANUAL SHIFT DETENT LEVER POSITION
TERMINALS P P/R R R/N N N/D4 D4 D4/D3 D3 D3/D2 D2 D2/D1 D1
K to J C C O O C C O O C C O O C
K to H O O O O O C C C C C C C C
K to G O C C C C C C C C O O O O
K to F C C C O O O O C C C C O O
F to J C C O O O O O O C C O O O
F to H O O O O O O O C C C C O O
F to G O C C O O O O C C O O O O
G to J O C O O C C O O C O O O O
G to H O O O O O C C C C O O O O
H to J O O O O O C O O C C O O C
C = CLOSED CIRCUIT
O = OPEN CIRCUIT
SPECIAL NOTE:
Terminals B, C, D, E, and F must indicate an "OPEN" circuit when
checked against the Internal Mode Switch shaft, through all ranges.
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Figure 8
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"INCORRECTLY" INSTALLED
G
A
B
C
P
"CORRECTLY" INSTALLED
Copyright © 2004 ATSG
Figure 9
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