P0634

P0634-PCM/ECM/TCM INTERNAL TEMPERATURE TOO HIGH

For a complete wiring diagram Refer to the Wiring Information.

Theory of Operation

The purpose of the diagnostic is to detect an over temperature shutdown of the Transmission Control Module (TCM) to protect the TCM hardware. The TCM has built in temperature sensor circuitry and they are located on the substrate of the TCM, therefore there is no possibility for electrical monitoring (circuit continuity), but out-of-range monitoring (transmitted temperature too low or too high) and a check of all TCM monitoring capabilities.

- When Monitored:
When the ignition switch is turned to the run position.

- Set Condition:
The failure is detected if one of the chip temperature sensors is greater than a calibrated threshold or if there is any failure detected on both chip temperature sensors.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. 8HP45 Pre-Diagnostic Troubleshooting Procedure

1. CHECK FOR RELATED TRANSMISSION TEMPERATURE DTCS
1. With the scan tool, read TCM DTCs.

Are any Transmission Fluid Temperature DTCs present?

Yes

- Testing and Inspection Perform the appropriate repair for those DTCs first.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.

No

- Go To 2

2. TRANSMISSION CONTROL MODULE ASSEMBLY (TCMA)

If there are no possible causes remaining, view repair.

Repair

- Using the schematics as a guide, check the TCMA terminals for corrosion, damage or terminal push out. Pay particular attention to power and ground circuits. Check Service Information Tune-ups or Service Bulletins for possible causes that may apply. If the DTC returns, replace and program the TCMA. Valve Body - Removal.
- Perform the TRANSMISSION VERIFICATION TEST. Verification Tests.