GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

    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.

    Important: Disconnecting the VCM will not erase the CKP System Variation Learn as long as the ignition switch is in the OFF position.

  1. Disconnect the negative battery cable.

  2. Object Number: 281662  Size: SH
  3. Disconnect the retainer clips and VCM harness connectors.
  4. Pull the wiring harness pin, which is underneath the wiring harness on top of the VCM bracket, out from the VCM bracket.

  5. Object Number: 281664  Size: SH
  6. Pinch the metal ends belonging to the V-clip together.
  7. Pull the V-clip out of the VCM bracket tongue.
  8. Push the VCM bracket tongue until the VCM bracket is free from the battery tray bracket.

  9. Object Number: 281668  Size: SH
  10. Guide the VCM bracket upwards and between the master cylinder reservoir and the A/C hose to remove the bracket out of the engine compartment.
  11. Press all three detente clips to separate the VCM bracket into two halves.
  12. Lift the VCM out of the VCM bracket.

  13. Object Number: 279289  Size: SH

    Important: The remaining steps are only necessary for a VCM replacement:

  14. Remove the access cover screws.
  15. Remove the VCM access cover.

  16. Object Number: 279302  Size: SH

    Important: Since the knock sensor module will be used in the replacement VCM, place the module in an area where it will not be damaged.

  17. Gently pinch the retaining clip and pull upward to remove the knock sensor module.

Installation Procedure

Important: Ensure that the VCM being installed is the original VCM, or that the replacement VCM service number is identical to the original VCM service number.


    Object Number: 279302  Size: SH

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

    Important: Steps 1-4 are only necessary for a new VCM installation:

  1. Align the notches of the knock sensor module with the notches in the knock sensor module socket.
  2. Important: Press only on the ends of the knock sensor module. Gently press on the knock sensor module until it is firmly seated in the socket. Listen for the click.

  3. Install the knock sensor module in the knock sensor module socket.

  4. Object Number: 279289  Size: SH
  5. Install the access cover on the VCM.
  6. 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.

  7. Install the access cover screws.
  8. Tighten
    Tighten the access cover screws to 4.8 N·m (42 lb in).


    Object Number: 281668  Size: SH
  9. Align the VCM with one of the VCM bracket halves.
  10. Snap the two VCM bracket halves together.
  11. Grasp the VCM bracket such that the RED VCM connector receptacle is located on the bottom and on the driver side of the vehicle.
  12. Guide the VCM bracket between the master cylinder reservoir and the A/C hose into the slot near the driver side wheel well.

  13. Object Number: 281664  Size: SH
  14. Insert the VCM bracket tongue into the retaining brace slot.
  15. Insert the V-clip into the VCM bracket tongue.

  16. Object Number: 281662  Size: SH
  17. insert the wiring harness pin into the VCM bracket hole.
  18. Connect the VCM electrical connectors and retainer clips.
  19. Connect the negative battery cable.
  20. Program the VCM.

VCM Programming

  1. Take the following steps in order to set-up for programming the VCM (EEPROM) .
  2. • The battery is fully charged.
    • The ignition is ON.
    • The Data Link Connector (DLC) is secure.
  3. Refer to an updated Techline terminal and follow the user's instructions for VCM programming.
  4. If the VCM fails to program, do the following functions:
  5. • Check all the VCM connections.
    • Check the ITCS terminal and equipment for the latest software version.
    • Try again to program the VCM. If the programming fails again, replace the VCM.
  6. Perform the VTD Password Learn Procedure. Refer to Password Learn .
  7. Perform the CKP System Variation Learn Procedure. Refer to Crankshaft Position System Variation Learn .
  8. For a functional check, perform the Powertrain On-Board Diagnostic (OBD) System Check.