P0634

DTC P0634

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC P0634
- Transmission Control Module (TCM) Overtemperature

Circuit/System Description

The transmission control module (TCM) temperature sensor is located inside of the control solenoid valve assembly which has no serviceable parts. The TCM monitors the TCM sensor for over temperature protection.

Conditions for Running the DTC

* Ignition voltage is between 8.6 volts or greater.
* The TCM temperature is between 0°C (32°F) and 170°C (338°F) for 0.25 seconds.
* DTC P0634 and has not set this ignition.

Conditions for Setting the DTC

Condition 1

The TCM has detected an internal temperature condition greater than 142°C (288°F) for 5 seconds.

Condition 2

Ignition voltage is equal to or greater than 18 volts and the TCM temperature is greater than 50°C (122°F) for 2 seconds.

Action Taken When the DTC Sets

* DTC P0634 is a Type A DTC.
* The TCM shifts to a default gear, shuts down, and turns OFF.
* The TCM disables TAP shift operation.
* The TCM enables torque management.

Conditions for Clearing the DTC

DTC P0634 is a Type A DTC.

Diagnostic Aids

During a road test, the TCM temperature should steadily increase to a normal operating temperature, then stabilize.

Reference Information
Description and Operation

Electronic Component Description (Electronic Component Description)
DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)

Circuit/System Verification

Note: If DTC P0218 is set, diagnose that DTC first.

1. Perform the Transmission Fluid Level and Condition Check (Transmission Fluid Level and Condition Check) to verify correct fluid level and condition.
2. Operate the vehicle to normal engine temperature is reached. Verify with a scan tool the engine coolant temperature (ECT) sensor parameter is less than 125°C (257°F).

• If greater than the specified value, refer to Symptoms - Engine Cooling (Symptoms - Engine Cooling).

3. Operate the vehicle till normal engine temperature is reached. Verify with a scan tool, the TCM temperature parameter is less than 142°C (287°F).

• If greater than the specified value, inspect the transmission fluid lines for being misrouted, kinked, or damage.

4. If all items test normal, replace the Q8 control solenoid valve assembly.
5. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Control solenoid valve assembly replacement. Refer to Control Module References (Programming and Relearning) for replacement, setup, and programming.
* Perform the Service Fast Learn Adapts (Programming and Relearning) following all transmission related repairs.