A normal function of the transmission control module (TCM) is to perform an internal test that verifies the integrity of the non-volatile random access memory (NVRAM) allocation. This diagnostic detects faults in the allocation of NVRAM that contain the transmission adaptive pressure memory cells by comparing a calculated checksum with a stored checksum. When the TCM detects that the calculated checksum is different from the stored checksum, DTC P0603 sets. DTC P0603 is a type A DTC.
This diagnostic procedure supports the following DTC:
DTC P0603 Transmission Control Module (TCM) Long Term Memory Reset
The ignition is ON.
The TCM NVRAM checksums do not match.
• | The TCM requests the ECM to illuminate the malfunction indicator lamp (MIL). |
• | The TCM commands maximum line pressure. |
• | The TCM freezes transmission adaptive functions. |
• | The TCM commands High Side Driver 1 OFF. |
• | The ECM records the operating conditions when the Conditions for Setting the DTC are met. The ECM stores this information as a Freeze Frame. |
• | The TCM stores DTC P0603 in TCM history. |
• | The ECM turns OFF the MIL after the sixth consecutive drive trip in which the TCM does not send a MIL illumination request. |
• | A scan tool can clear the MIL/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 default actions when the ignition is OFF long enough in order to power down the TCM. |
DTC P0603 may set as result of TCM reprogramming.
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||
---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | ||||
2 |
Important:
Did DTC P0603 reset? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||
Perform the Transmission Control Module Reprogramming Procedure. Refer to Control Module References in Computer/Integrating Systems for replacement, set-up and programming. Is the action complete? | -- | Go to Step 5 | Go to Step 4 | |||||
4 | Replace the TCM. Refer to Control Module References in Computer/Integrating Systems for replacement, set-up and programming. Is the action complete? | -- | 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? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information | System OK |