Circuit Description
The transmission control module (TCM) is equipped with an internal temperature sensor mounted directly to the TCM circuit board. The TCM will take action to protect against damage from overheating.
DTC P0634 is a type B DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0634 Transmission Control Module (TCM) Internal Temperature Too High
Conditions for Running the DTC
| • | The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts. |
| • | Engine speed is greater than 200 RPM and less than 7,500 RPM for greater than 10 seconds. |
Conditions for Setting the DTC
DTC P0634 sets if the TCM internal temperature is greater than or equal to 140°C (284°F) for 10 seconds with the engine running.
Action Taken When the DTC Sets
| • | The TCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met. |
| • | When DTC P0613 is active, the TCM commands all transmission solenoids to OFF. |
| • | DTC P0634 is stored in TCM history. |
| • | The TCM inhibits torque converter clutch (TCC) engagement. |
Conditions for Clearing the MIL/DTC
A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.
Diagnostic Aids
Clean the TCM if necessary. Excessive road debris will reduce the effectiveness of the heat sink on the TCM and could cause the internal temperature to rise.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Automatic Transmission Controls Schematics | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data. Did DTC P0634 return? | Go to Step 3 | Go to Diagnostic Aids |
3 |
Do you find and correct the condition? | Go to Step 5 | Go to Step 4 |
4 |
Important: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM. Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | -- |
5 | Perform the following procedure in order to verify the repair:
Has the test run and passed? | Go to Step 6 | Go to Step 2 |
6 | With the scan tool, observe the stored information, capture info, and DTC Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | |
