Service Information

Cruze

DTC P0634

Diagnostic Instructions

•	Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

•	Review Strategy Based Diagnosis for an overview of the diagnostic approach.

•	Diagnostic Procedure Instructions provides an overview of each diagnostic category.

The transmission control module (TCM) temperature sensor is located inside of the control solenoid valve assembly which has no serviceable components. 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 second or greater.

•	DTC P0634 is not set.

•	The ignition voltage is greater than 9.0 volts.

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 limits the transmission to 5th gear and reverse.

•	The TCM inhibits Tap Up/Down function.

•	The TCM enables torque management.

•	The TCM commands maximum line pressure.

•	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 stabilise.

Reference Information

Description and Operation

Electronic Component Description for control solenoid valve assembly information.

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

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

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 .

Perform the Transmission Fluid Level and Condition Check to verify correct fluid level and condition.
Perform the Transmission Fluid Cooler Flushing and Flow Test to verify proper transmission oil cooler flow.
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 valve assembly.

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 after completing the diagnostic procedure.

•	Refer to Control Module References for control solenoid valve assembly replacement, set-up, and programming.

•	Perform the Transmission Adaptive Values Learn following all transmission related repairs.

•	Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection .