6T30/6T40/6T45/6T50 - 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
- 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 temperature sensor for over temperature protection.

Conditions for Running the DTC

* DTC P0634 is not set.

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

* Ignition voltage is 9-32 V.

Conditions for Setting the DTC

Condition 1

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

Condition 2

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

Action Taken When the DTC Sets

* DTC P0634 is a Type A DTC.

* TCM limits the transmission to 4th gear and reverse.

* TCM inhibits Tap Up/Down function.

* TCM inhibits manual shifting of forward gears.

* 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

Schematic Reference

Automatic Transmission Controls Schematics 6T30/6T40/6T45/6T50 - Automatic Transmission

Connector End View Reference

* Component Connector End Views Sunshade - Left Front

* Inline Harness Connector End Views X110

Description and Operation

* Transmission General Description Transmission General Description

* Transmission Component and System Description Transmission Component and System Description

* Electronic Component Description Electronic Component Description

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

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 transmission fluid level and condition is correct. Refer to Transmission Fluid Level and Condition Check 6T30/6T40/6T45/6T50 - Automatic Transmission.

• If the transmission fluid level and condition is not correct
Repair as necessary.

• If the transmission fluid level and condition is correct

4. Clear the DTCs from the TCM.

5. Operate the vehicle until normal engine temperature is reached.

6. 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

1. Ignition OFF.

2. Verify the conditions listed below do not exist:

* Obstructions to the airflow to the radiator or transmission

* Radiator damage

* Transmission cooler damage

* Transmission cooler pipe kinked or damaged

• If conditions exist, repair or replace as necessary.

• If conditions do not exist, refer to Transmission Fluid Cooler Flushing and Flow Test Transmission Fluid Cooler Flushing and Flow Test.

• If less than 140°C (284°F)

7. Verify DTC P0634 does not set.

• If the DTC sets
Replace the Q8 Control Solenoid Valve Assembly.

• If the DTC does not set

8. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

9. Verify the DTC does not set.

• If the DTC sets
Replace the Q8 Control Solenoid Valve Assembly.

• If the DTC does not set

10. All OK.

Repair Instructions

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

* Perform the Transmission Adaptive Values Learn 6T30/6T40/6T45/6T50 - Automatic Transmission following all transmission repairs.

* Transmission Fluid Cooler Pipe Connector Replacement - Radiator Transmission Fluid Cooler Pipe Connector Replacement - Radiator

* Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection Transmission Fluid Cooler Hose/Pipe Quick-Connect Fitting Disconnection and Connection

* Transmission Fluid Cooler Outlet Pipe Replacement Transmission Rear Mount Bracket Replacement (AWD)

* Transmission Fluid Cooler Inlet Pipe Replacement Transmission Fluid Cooler Outlet Pipe Replacement

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