GM Service Manual Online
For 1990-2009 cars only

Engine control module (ECM) service should normally consist of either ECM replacement or electrically erasable programmable read only memory (EEPROM) programming. If the diagnostic procedures require ECM replacement, check the ECM first to see if the correct part is being used.

Important: In order to prevent internal ECM damage, the ignition must be OFF when you disconnect or reconnect the power to the ECM. For example, disconnect the power when you work with the following components:

    • A battery cable
    • The ECM pigtail
    • The ECM fuse
    • The jumper cables

Important: When you diagnose or replace the ECM, remove any debris from the ECM connector surfaces before servicing the ECM module connector gaskets. Ensure that the gaskets are installed correctly. The gaskets prevent intrusion into the ECM.

Important: The replacement ECM MUST be programmed.

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 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. Remove the wheelhouse filler panel. Refer to Fender, Insulator, Liner, Brake Caliper Cooling Duct Replacement - Front in Body Front End.

  3. Object Number: 1656723  Size: SH
  4. Disconnect the ECM electrical harness connectors.
  5. Loosen but do not remove the ECM rear retaining fastener. Use the rear retaining fastener as an anchor for the outer bracket.
  6. Remove the front retaining fastener from the ECM.
  7. Reposition the ECM outer bracket.

  8. Object Number: 1656726  Size: SH
  9. Remove the ECM from the bracket and the vehicle.

Installation Procedure


    Object Number: 1656723  Size: SH
  1. Install the ECM to the ECM rear bracket.
  2. Position the ECM front bracket.
  3. Notice: Refer to Fastener Notice in the Preface section.

  4. Install the ECM front retaining fasteners.
  5. Tighten
    Tighten the ECM retaining fasteners to 2.0 N·m (17 lb in).


    Object Number: 1656726  Size: SH
  6. Connect the electrical connectors to the ECM.
  7. Tighten
    Tighten the ECM electrical connectors to 8 N·m (70 lb in).

  8. Install the wheelhouse filler panel. Refer to Fender, Insulator, Liner, Brake Caliper Cooling Duct Replacement - Front in Body Front End.
  9. If a new ECM is being installed, program the ECM. Refer to Control Module References in Computer/Integrating Systems.