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Jeep Grand Cherokee WK. Manual - part 1463
U1406-IMPLAUSIBLE MAXIMUM ENGINE TORQUE SIGNAL RECEIVED (CONTINUED)
For the Transmission circuit diagram (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - NAG1 - SCHE-
MATICS AND DIAGRAMS)
For a complete wiring diagram Refer to Section 8W
Theory of Operation
The messages sent on the CAN bus are distinguished by an identifier (ID). Each CAN ID is defined to contain a
certain number of bytes. The Transmission Control Module (TCM) verifies that it has received the proper number of
bytes for each ID.
•
When Monitored:
Continuously with the ignition on, one valid CAN ID received at least once, and no U0002-CAN Bus Off Per-
formance DTC present.
•
Set Condition:
When the TCM detects an incorrect CAN ID from the ECM/PCM.
Possible Causes
FCM CAN BUS DTC’S PRESENT
ECM/PCM DTC’S PRESENT
TRANSMISSION CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - NAG1 - STANDARD PROCEDURE)
Diagnostic Test
1.
CHECK FOR FCM CAN BUS DTCS
With the scan tool, read FCM DTCs.
Are there any FCM CAN BUS DTC’s present?
Yes
>> Refer to 8-ELECTRICAL - ELECTRONIC CONTROL MODULES - ELECTRICAL DIAGNOSTICS cate-
gory and perform the appropriate symptom.
No
>> Go To 2
2.
CHECK IF ENGINE DTC’S ARE PRESENT
With the scan tool, read engine DTCs.
Are there any engine DTC’s present?
Yes
>> Refer to the 9 - ENGINE ELECTRICAL DIAGNOSTICS and diagnose the appropriate symptom.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No
>> Using the schematics as a guide, check the Transmission Control Module (TCM) pins, terminals, and
connectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground
circuits. If no problems are found, replace the TCM per the Service Information. Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE for the appropriate
service procedure.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
21 - 662
AUTOMATIC TRANSMISSION NAG1 - ELECTRICAL DIAGNOSTICS
WK