GM Service Manual Online
For 1990-2009 cars only

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

Service of the PCM should normally consist of either replacement of the PCM or EEPROM re-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. DTC P0601 indicates the EEPROM programming has malfunctioned. When DTC P0601 is obtained, re-program the EEPROM.

The ignition should be OFF for at least 10 seconds before disconnecting power to the PCM so the IAC valve has time to move to the engine OFF position.

Removal Procedure

Important: Turn OFF the ignition in order to prevent internal PCM damage when you disconnect or re-connect power to the PCM via the battery cable, the PCM pigtail, the PCM fuse, the jumper cables, or via other components. The ignition switch should be OFF for at least 10 seconds before disconnecting the power to the PCM so the IAC valve has time to move to the engine OFF position.

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Disconnect the negative battery cable.
  2. Caution: To avoid any vehicle damage, serious personal injury or death when major components are removed from the vehicle and the vehicle is supported by a hoist, support the vehicle with jack stands at the opposite end from which the components are being removed and strap the vehicle to the hoist.

  3. Lift the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  4. Remove the right engine splash shield Engine Splash Shield Replacement .
  5. Disconnect the horn electrical connector.
  6. Remove the horn.

  7. Object Number: 51591  Size: SH

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

  8. Disconnect the PCM electrical connectors (1).

  9. Object Number: 51604  Size: SH
  10. Remove the PCM attaching bolts (1).

  11. Object Number: 51596  Size: SH
  12. Slide the PCM assembly (1) and protective cover (if equipped) from the PCM bracket (2).

  13. Object Number: 51600  Size: SH
  14. Remove the protective cover (if equipped and note position).
  15. Remove the retainer (1) from the PCM (2).

Installation Procedure


    Object Number: 51600  Size: SH

    Important: Remove the replacement PCM from its packaging. Check the service number to ensure that the number is the same number as the malfunctioning PCM, or an updated number.

  1. Slide the PCM  (2) into the PCM retainer (1).
  2. Reinstall the protective cover (if equipped).


    Object Number: 51596  Size: SH
  3. Slide the PCM assembly (1) into the PCM bracket slots (2).

  4. Object Number: 51604  Size: SH

    Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  5. Install the PCM attaching bolts (1).
  6. Tighten
    Tighten the PCM attaching bolts to 10 N·m (89 lb in).


    Object Number: 51591  Size: SH

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

  7. Connect the PCM electrical connectors (1).
  8. Tighten
    Tighten the PCM electrical connectors screws to 8 N·m (71 lb in).

  9. Install the horn.
  10. Tighten
    Tighten the horn retainer bolt to 10 N·m (89 lb in).

  11. Connect the horn electrical connector.
  12. Install the right engine splash shield Engine Splash Shield Replacement .
  13. Caution: To avoid any vehicle damage, serious personal injury or death when major components are removed from the vehicle and the vehicle is supported by a hoist, support the vehicle with jack stands at the opposite end from which the components are being removed and strap the vehicle to the hoist.

  14. Lower the vehicle.
  15. Connect the negative battery cable.
  16. Reprogram the PCM and complete the crankshaft position system variation learn procedure Crankshaft Position System Variation Learn .