Circuit Description
The internal fault detection is handled inside the transmission control module (TCM). No external circuits are involved.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC P0601 Transmission Control Module (TCM) Read Only Memory (ROM) |
| • | DTC P0602 Transmission Control Module (TCM) Not Programmed |
| • | DTC P0603 Transmission Control Module (TCM) Long Term Memory Reset |
| • | DTC P0604 Transmission Control Module (TCM) Random Access Memory (RAM) |
Conditions for Running the DTC
The TCM runs the program to detect an internal fault when the engine is running. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.
Conditions for Setting the DTC
The TCM has detected an internal malfunction.
Action Taken When the DTC Sets
| • | The TCM requests the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL). |
| • | The TCM commands a soft landing to second gear, P0601, P0603 and P0604. |
| • | The TCM commands an immediate landing to second gear, P0602. |
| • | The TCM commands maximum line pressure. |
| • | The TCM forces the torque converter clutch (TCC) OFF. |
| • | The TCM inhibits TCC engagement. |
| • | The TCM freezes transmission adaptive functions. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record. |
| • | The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame. |
Conditions for Clearing the DTC
| • | The ECM turns off the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | A scan tool can clear the DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
Is DTC P0602 set? | Go to Step 3 | Go to Step 4 | |
3 | Program the TCM. Refer to Control Module References for replacement, setup and programming. Does DTC P0602 reset? | Go to Step 4 | Go to Step 5 |
4 | Replace the TCM. Refer to Control Module References for replacement, setup and programming. Did you complete the replacement? | Go to Step 5 | -- |
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 |
