Jeep Grand Cherokee WK. Manual — part 1440

P1633-TCM INTERNAL - TEST EXTERNAL WATCHDOG PERFORMANCE

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AUTOMATIC TRANSMISSION NAG1 - ELECTRICAL DIAGNOSTICS

WK

P1633-TCM INTERNAL - TEST EXTERNAL WATCHDOG PERFORMANCE (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 Transmission Control Module (TCM) performs various internal tests to verify proper controller operation. This
DTC indicates that there is an issue with the TCM’s external watchdog. If the TCM detects an error with the con-
trollers external watchdog failed the power up test, the controller will enter Limp-in mode and illuminate the MIL.

•

When Monitored:
Continuously with the ignition on.

•

Set Condition:
If the TCM detects an error with the controllers external watchdog failed the power up test.

Possible Causes

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.

TRANSMISSION CONTROL MODULE

View repair

Repair

Using the schematics as a guide, check the Transmission Control Module (TCM) terminals 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 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/TRANSMISSION CONTROL MODULE for the appropriate service procedures.

Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

WK

AUTOMATIC TRANSMISSION NAG1 - ELECTRICAL DIAGNOSTICS

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P1634-TCM INTERNAL- INTERNAL WATCHDOG PERFORMANCE

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AUTOMATIC TRANSMISSION NAG1 - ELECTRICAL DIAGNOSTICS

WK

P1634-TCM INTERNAL- INTERNAL WATCHDOG PERFORMANCE (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 Transmission Control Module (TCM) performs various internal tests to verify proper controller operation. This
DTC indicates that the controller’s microprocessor internal watchdog has detected an error. If the TCM micropro-
cessor detects an internal watchdog error, the controller will enter Limp-in mode and illuminate the MIL.

•

When Monitored:
Continuously with the ignition on.

•

Set Condition:
If the TCM microprocessor internal watchdog detects an error.

Possible Causes

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.

TRANSMISSION CONTROL MODULE

View repair

Repair

Using the schematics as a guide, check the Transmission Control Module (TCM) terminals 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 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/TRANSMISSION CONTROL MODULE for the appropriate service procedures.

Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.

WK

AUTOMATIC TRANSMISSION NAG1 - ELECTRICAL DIAGNOSTICS

21 - 573