GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2004 🢒 CTS 🢒 Transmission/Transaxle 🢒 Automatic Transmission - 5L40-E 🢒 DTC P0603

Circuit Description

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.

Conditions for Running The DTC

The ignition is ON.

Conditions for Setting The DTC

The TCM NVRAM checksums do not match.

Action Taken When the DTC Sets
    • 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 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.

Conditions for Clearing the MIL/DTC
    • 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.

Diagnostic Aids

DTC P0603 may set as result of TCM reprogramming.

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step eliminates the TCM software as a possible cause of the DTC. If the DTC continues to set after reprogramming, the fault is in the TCM hardware.

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check - Automatic Transmission?

--

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2

  1. Install a scan tool.
  2. Turn ON the ignition with the engine OFF.

    3. Important: 

       • Before clearing the DTC, use the scan tool in order to record the ECM Freeze Frame and the TCM Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the ECM and the TCM.
       • Using the Clear Info function erases stored DTCs in both the ECM and TCM.

  3. Record the DTC Failure Records.
  4. Clear the DTC.
  5. Turn OFF the ignition for at least 30 seconds.
  6. Turn ON the ignition.

Did DTC P0603 reset?

--

Go to Step 3

Go to Diagnostic Aids

3

Perform the Transmission Control Module Programming Procedure. Refer to Transmission Control Module Programming .

Is the action complete?

--

Go to Step 5

Go to Step 4

4

Replace the TCM. Refer to Transmission Control Module Replacement .

Is the action complete?

--

Go to Step 5

--

5

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear Info.
  3. Turn OFF the ignition for at least 30 seconds.
  4. Turn ON the ignition.
  5. Select Specific DTC.
  6. Enter DTC P0603.

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 in Engine Controls - 2.6L and 3.2L or Diagnostic Trouble Code (DTC) List in Engine Controls - 3.6L (LY7)

System OK