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
- Control Module Overtemperature

Circuit/System Description

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

* TCM temperature is between 0°C (32°F) and 240°C (464°F) for 0.25 seconds or greater.

* DTC P0634 is not set.

* Ignition voltage is 9.0 volts or greater.

Conditions for Setting the DTC

Condition 1

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.

* TCM limits the transmission to 5th gear and reverse.

* TCM inhibits Tap Up/Down function.

* TCM enables torque management.

* TCM shuts down.

* TCM commands maximum line pressure.

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 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 Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify the scan tool Engine Coolant Temperature parameter was less than 125°C (257°F) when DTC set by reviewing the scan tool Freeze Frame/Failure Records.

• If 125°C (257°F) or greater
Refer to Engine Overheating Engine Overheating.

• If less than 125°C (257°F)

3. Verify the scan tool TCM Temperature parameter is less than 146°C (295°F).

• If 146°C (295°F) or greater
Replace the Q8 control solenoid valve assembly.

• If less than 146°C (295°F)

4. Verify correct fluid level and condition. Refer to Transmission Fluid Level and Condition Check Testing and Inspection.

5. Clear the DTCs from the TCM using a scan tool.

6. Operate the vehicle within the conditions for running and setting the DTC until normal engine temperature is reached.

7. Verify the scan tool Transmission Fluid Temperature parameter is less than 140°C (284°F) and DTC P0634 did not set.

• If 140°C (284°F) or greater
Inspect the transmission cooling system for 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 problems with cooling system are found, repair or replace as necessary.

• If no problems are found, refer to Refer to Transmission Fluid Cooler Flushing and Flow Test Transmission Fluid Cooler Flushing and Flow Test.

• If less than 140°C (284°F) and DTC P0634 set
Replace the Q8 control solenoid valve assembly.

• If less than 140°C (284°F) and DTC P0634 did not set

8. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions you observe from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Refer to Control Module References Control Module References for control solenoid valve assembly replacement, programming and setup.

* Perform the Transmission Adaptive Values Learn Programming and Relearning following all transmission related repairs.

* Before replacing the TCM, perform the Control Solenoid Valve and Transmission Control Module Assembly Inspection (Gen 1 with 1.4L - LCU, 1.6L - LDE or LFJ, 1.8L - LUW) Control Solenoid Valve and Transmission Control Module Assembly Inspection (Gen 1 with 1.4L - LCU, 1.6L - LDE or LFJ, 1.8L - LUControl Solenoid Valve and Transmission Control Module Assembly Inspection (Gen 2 with 1.4L - LUV) Control Solenoid Valve and Transmission Control Module Assembly Inspection (Gen 2 with 1.4L - LUV).