The control solenoid (w/body and TCM) valve assembly has a built-in TCM temperature sensor to detect possible overtemperature conditions of the TCM. This fault indicates the TCM is in an overtemperature condition and the TCM has shut down to protect from possible heat damage to the TCM. The TCM will remain off until the over temperature condition no longer exists.

DTC P0634 is a Type A DTC.

Inspect the transmission cooler, transmission fluid lines, engine cooling system, and transmission fluid level, and inspect for any obstructions in the cooling system airflow which may cause an overheat condition. Inquire about customer towing or extreme driving conditions. An engine cooling system or transmission cooling system malfunction may cause this diagnostic to set. Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection before replacing the control solenoid (w/body and TCM) valve assembly.

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

DTC Type Reference

Electrical Information Reference

Start the engine and check for DTC P0634.

1. Start the engine.
2. Observe the transmission fluid temperature (TFT) and the engine coolant temperature (ECT). Ensure there are no current overheat conditions present in these systems.

⇒	If an overheating concern is found, diagnose and repair that system first.

3. Operate the vehicle under the same conditions as found in Failure Records and observe the TCM Temperature parameter on the scan tool.
4. Recheck for DTCs.

⇒	If the DTC resets, and the TCM power-up temperature sensor is not over 130°C (266°F), and the TFT is less than 120°C (248°F), replace the control solenoid (w/body and TCM) valve assembly.

⇒	If the TCM power-up temperature sensor is over 130°C (266°F), inspect and repair the transmission cooler, transmission cooler fluid lines, engine cooling system, and transmission fluid level, and inspect for any obstructions in the cooling system airflow which may cause an overheat condition.

5. Inquire about customer towing or extreme driving conditions.

Perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. Control solenoid (w/body and TCM) valve assembly replacement. Refer to Control Module References for replacement, setup, and programming.
2. Perform the Service Fast Learn Adapts .