GM Service Manual Online
For 1990-2009 cars only

Notice: In order to prevent possible electrostatic discharge damage to the PCM, do not touch the connector pins or soldered components on the circuit board.

Service of the PCM should normally consist of either replacement of the PCM or EEPROM programming. If the diagnostic procedures call for PCM Replacement, check the PCM first to see if it is the correct part. If the PCM is faulty, remove it and install the new service PCM.

The new service PCM will not be programmed. You must program the new PCM. DTC P0602 indicates the EEPROM is not programmed or has malfunctioned.

Notice: Do not touch the connector pins or soldered components on the circuit board in order to prevent possible electrostatic discharge (ESD) damage to the PCM.

Notice: Turn the ignition OFF when installing or removing the PCM connectors and disconnecting or reconnecting the power to the PCM (battery cable, PCM pigtail, PCM fuse, jumper cables, etc.) in order to prevent internal PCM damage.

Important: When replacing the production PCM with a service PCM (controller), it is important to transfer the broadcast code and production PCM number to the service PCM label. Do not record on PCM cover. This will allow positive identification of PCM parts throughout the service life of the vehicle.

Notice: Turn the ignition OFF when installing or removing the PCM connectors and disconnecting or reconnecting the power to the PCM (battery cable, PCM pigtail, PCM fuse, jumper cables, etc.) in order to prevent internal PCM damage.

Removal Procedure

    Important: It is necessary to record the remaining engine oil life. If the replacement module is not programed with the remaining engine oil life, the engine oil life will default to 100%. If the replacement module is not programmed with the remaining engine oil life, the engine oil will need to be changed at 5 000 km (3,000 mi) from the last engine oil change.

  1. Using a scan tool, retrieve the percentage of remaining engine oil. Record the remaining engine oil life.

  2. Object Number: 21745  Size: SH
  3. Disconnect the negative battery cable.
  4. Remove the PCM from the mounting hardware.
  5. Disconnect the harness connectors from the PCM.
  6. Remove the PCM from the engine compartment.

Installation Procedure


    Object Number: 21745  Size: SH
  1. Avoid Electrostatic Discharge. Do not touch terminals with your fingers.
  2. Connect the harness connectors to the PCM.
  3. Position and install the PCM into the vehicle.
  4. Connect the negative battery cable.
  5. If you are installing a new PCM, program the new PCM EEPROM.

EEPROM Programming

  1. Set-up - Ensure that the following conditions have been met:
  2. • The battery is fully charged.
    • The ignition is ON.
    • The Vehicle Interface Module cable connection at the DLC is secure.
  3. Program the PCM using the latest software matching the vehicle. Refer to up-to-date Techline equipment user's instructions.
  4. If the PCM fails to program, proceed as follows:
  5. • Ensure that all PCM connections are OK.
    • Check the Techline equipment for the latest software version.
    • Attempt to program the PCM. If the PCM still cannot be programmed properly, replace the PCM. You must program the replacement PCM.

Functional Check

  1. Perform the On-Board Diagnostic System Check.
  2. Start the engine and the engine run for one minute.
  3. Use the scan tool in order to scan for the DTCs.