P0634

DTC P0634

Diagnostic Instructions

* Perform theDiagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* ReviewStrategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



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




Circuit/System Description

A thermistor is imbedded in the transmission control module (TCM). There are no external circuits. The TCM monitors the temperature and will take action to prevent damage to the TCM.


Conditions for Running the DTC

* Engine speed is greater than 200 RPM for 5 seconds.
* Ignition and battery voltage is between 9-18 V.



Conditions for Setting the DTC

This DTC sets when the TCM internal temperature is greater than 140°C (284°F) for 10 seconds.


Action Taken When the DTC Sets

* The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).
* DTC P0634 is stored in TCM history.
* The TCM shuts down and all power is removed from the solenoids.
* The transmission goes to a hydraulic default mode and will operate in reverse, neutral, and first, third, or fifth range.



Conditions for Clearing the DTC

DTC P0634 is a Type C DTC.


Diagnostic Aids

* Inspect the mounting of the TCM and damage or missing heat shields.
* You may have to drive the vehicle in order to experience a condition.



Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
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 (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

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

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Prior to cold start, Ignition ON, observe the TCM Temperature parameter with a scan tool. The TCM Temperature parameter should be approximately the same as the ambient temperature.
2. Perform a road test while observing the TCM Temperature parameter with a scan tool. The TCM Temperature parameter should rise and then stabilize.
3. 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 on the Freeze Frame/Failure Records data.



Circuit/System Testing



Note

You must perform the Circuit/System Verification first.

1. Replace the TCM. Refer to Control Module References (Programming and Relearning) for TCM replacement, setup, and programming.
2. Perform fast learn procedure. Refer to FastLearn Procedure (Programming and Relearning) .



Repair Instructions

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

* Control Module References (Programming and Relearning) for TCM replacement, setup, and programming
* FastLearn Procedure (Programming and Relearning)



Repair Verification

If another DTC is present, refer toDiagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) and perform the appropriate diagnostic procedure.