6T30/6T40/6T45 - Automatic Transmission

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 (w/body and TCM) valve assembly which has no serviceable parts. The TCM monitors the TCM sensor for over temperature protection.

Conditions for Running the DTC

* The TCM temperature is between 0°C (32°F) and 240°C (464°F) for 0.25 seconds or greater.
* DTC P0634 has not set.

Conditions for Setting the DTC

Condition 1

The TCM has detected an internal temperature condition greater than 144°C (291°F) for 5 seconds or greater.

Condition 2

Ignition voltage is 18 volts or greater 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 defaults the transmission to 5th gear and reverse.
* The TCM inhibits Tap Up/Down function.
* The TCM enables torque management.
* The TCM shuts down.

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, and then stabilize.

Reference Information
Description and Operation

Electronic Component Description Electronic Component Description for control solenoid (w/body and TCM) valve assembly information.
DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference

Control Module References Programming and Relearning for scan tool information

Circuit/System Verification

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

1. Ignition ON, review the Failure Records when the DTC set. Verify the scan tool ECT Sensor parameter was less than 125°C (257°F).

• If greater than the specified range, refer to Engine Overheating Engine Overheating.

2. Perform the Transmission Fluid Level and Condition Check Transmission Fluid Level and Condition Check to verify correct fluid level and condition.
3. Perform the Transmission Fluid Cooler Flushing and Flow Test Transmission Fluid Cooler Flushing and Flow Test to verify proper transmission oil cooler flow.
4. Operate the vehicle within the conditions for running and setting the DTC until normal engine temperature is reached. Verify the scan tool TCM Temperature parameter is less than 146°C (295°F).

• If greater than the specified range, inspect the transmission cooling system. Obstructions to the airflow of the radiator or transmission due to debris, kinked or damaged transmission fluid lines, or damage to the transmission cooler. If all the items test normal, replace the control solenoid (w/body and TCM) 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.

* Refer to Control Module References Programming and Relearning for control solenoid (w/body and TCM) valve assembly replacement, setup, and programming.
* Perform the Service Fast Learn Adapts 6T30/6T40/6T45 - Automatic Transmission following all transmission related repairs.
* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection Control Solenoid Valve and Transmission Control Module Assembly Inspection.