GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Holden 🢒 2005 🢒 Caprice WL 🢒 DTC 🢒 DTC P0601, P0602, P0603, P0604, or P1621

DTC P0601, P0602, P0603, P0604, or P1621 V6

DTC Description

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)
    • DTC P1621 Transmission Control Module (TCM) Long Term Memory Performance

Circuit Description

The internal fault detection is handled inside the transmission control module (TCM). No external circuits are involved. These DTCs are type A DTCs.

Refer to 2 Wiring Diagram and Connector Chart to aid in diagnosis.

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 ECM to illuminate the check powertrain icon.
    • The TCM allows the vehicle to operate in transmission protection mode.
    • 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 check powertrain icon after the third consecutive drive trip in which the TCM does not send a check powertrain icon illumination request.
    • Tech 2 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 following numbers refer to the step numbers in the diagnostic table:

2 DTC P0602 indicates the TCM is not programmed.

Step

Action

Yes

No

1

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to Diagnostic System Check - Automatic Transmission

2
  1. Connect Tech 2 to the DLC.
  2. Turn on the ignition, with the engine off.
  3. On Tech 2 select: Transmission/Automatic Transmission/Diagnostic Trouble Codes/Read DTC Information.

Has DTC P0602 set?

Go to Step 3

Go to Step 4

3
  1. On Tech 2 select: Diagnostic Trouble Codes/Clear Engine and Transmission DTCs.
  2. Follow the instructions on Tech 2 and clear any DTCs.
  3. Program the TCM, refer to Section 7C4 Automatic Transmission-4L60E -On-vehicle Servicing.
  4. On Tech 2 select: Diagnostic Trouble Codes/Read DTC Information.

Has DTC P0602 set?

Go to Step 4

Go to Step 5

4

Replace the TCM, refer to Section 7C4 Automatic Transmission-4L60E -On vehicle Servicing.

Did you complete the replacement?

Go to Step 5

--

5

Perform the following procedure in order to verify the repair:

  1. On Tech 2 select: Diagnostic Trouble Codes/Clear Engine andTransmission DTCs.
  2. Follow the instructions on Tech 2 and clear any DTCs.
  3. Start the engine.
  4. On tech 2 select: Diagnostic Trouble Codes/Read DTC Information.

Have any of the DTCs in this procedure set?

Go to Step 2

Go to Step 6

6

On tech 2 select: Diagnostic Trouble Codes/Read DTC Information.

Does Tech 2 display any DTCs you have not diagnosed?

Refer to Diagnostic Trouble Code (DTC) List/Type

System OK

When all diagnosis and repairs are completed, check the system for correct operation.