GM Service Manual Online
For 1990-2009 cars only

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

THE SERVICE PCM EEPROM WILL NOT BE PROGRAMMED. DTC P0601 and P0602 indicates the EEPROM is not programmed or has malfunctioned.

Important:: The following must be performed anytime the PCM is replaced:

  1. Programming of the EEPROM
  2. The PCM Password learn procedure. Refer to DTC P1631 Theft Deterrent Start Enable Signal Not Correct .
  3. The Idle Learn Procedure. Refer to PCM Idle Learn Procedure .
  4. The CKP System Variation Learn Procedure. Refer to Crankshaft Position System Variation Learn .
  5. Reset the Engine Oil Life monitor. Refer to Engine Oil Life Monitor Reset .
  6. The Functional Check
The following must be performed anytime the PCM is disconnected, loses power, or is reprogrammed.

  1. The Idle Learn Procedure. Refer to PCM Idle Learn Procedure .
  2. The Functional Check

Important:: To prevent internal PCM damage, the ignition must be OFF when disconnecting or reconnecting power to the PCM (for example, battery cable, PCM pigtail, PCM fuse, jumper cables, etc.).

Removal Procedure

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM module connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM.

    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 5000 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: 334905  Size: MH
  3. Release the PCM cover mounting holes (1, 5) away from the mounting tabs on the PCM mounting bracket.
  4. Release the PCM cover (8) from the mounting bracket.
  5. Remove the PCM cover.
  6. 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: In order to prevent internal damage to the PCM, the ignition must be OFF when disconnecting or reconnecting the PCM connector.

  7. Disconnect the PCM harness connectors (6).
  8. Release the spring latch (2) from the PCM.
  9. Release the PCM mounting tabs (3) from the PCM.
  10. Remove the PCM (4) from the engine compartment.

Installation Procedure

    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: In order to prevent internal damage to the PCM, the ignition must be OFF when disconnecting or reconnecting the PCM connector.


    Object Number: 334905  Size: MH
  1. Install the PCM (4) to the PCM mounting bracket (7) ensuring that the mounting tabs (3) are engaged.
  2. Secure the spring latch (2) to the PCM.
  3. Connect the PCM connectors (6) to the PCM (4).
  4. Tighten
    Tighten the PCM connector end fasteners to 8 N·m (70 lb in).

  5. Install the PCM cover (8) to the PCM mounting bracket (7), ensuring the mounting tabs on the PCM mounting bracket are engaged into the mounting holes in the PCM cover.
  6. If a new PCM is being installed, program the EEPROM.

PCM Programming

  1. Setup - Ensure that the following conditions have been met:
  2. • The battery is fully charged.
    • The ignition is ON.
  3. Program the PCM using the latest software matching the vehicle. Refer to Techline terminal/equipment users instructions.
  4. If the PCM fails to program, proceed as follows:
  5. • Ensure that all PCM connections are OK.
    • Check the Techline terminal/equipment for the latest software version.
    • Attempt to program the PCM. If the PCM still cannot be programmed properly, replace the PCM. The replacement PCM must be programmed.
  6. Perform the PCM Password learn procedure. Refer to DTC P1631 Theft Deterrent Start Enable Signal Not Correct .
  7. Perform the Idle Learn Procedure. Refer to PCM Idle Learn Procedure .
  8. Perform the CKP System Variation Learn Procedure. Refer to Crankshaft Position System Variation Learn .
  9. The Functional Check

Functional Check

  1. Clear the Diagnostic Trouble Codes (DTCs).
  2. Perform the On-Board Diagnostic System Check.
  3. Start the engine and idle for one minute.
  4. Use the scan tool in order to check for DTCs.