GM Service Manual Online
For 1990-2009 cars only

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: 

   • Service of the vehicle control module (VCM) consists of either replacement of the VCM or reprogramming of the VCM.
   • If the VCM is being replaced, the knock sensor (KS) module must be transferred to the replacement VCM.
   • The replacement VCM must be programmed before the vehicle will run.
   • The replacement VCM must have the Passlock Reprogramming procedure performed before the vehicle will run.
   • The replacement VCM must have the CKP System Variation Learn procedure performed or a DTC P1336 will set.

A shorted solenoid, relay coil, or harness will not damage the output driver module (ODM) in the VCM. A shorted solenoid, relay coil, or harness will cause the circuit and the controlled component to be inoperative.

When the circuit fault is not present or the technician has repaired the fault, the output driver module (ODM) will again operate in a normal manner due to its fault protected design.

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.

  1. Disconnect the negative battery cable.

  2. Object Number: 234993  Size: SH
  3. Remove the harness connectors from the VCM.

  4. Object Number: 234989  Size: SH
  5. Remove the VCM bracket bolts.
  6. Remove the VCM and bracket from the VCM support.

  7. Object Number: 279288  Size: SH
  8. Separate the VCM from the bracket.

  9. Object Number: 279289  Size: SH

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

  10. Remove the Knock Sensor Module access cover screws.
  11. Remove the Knock Sensor Module cover.

  12. Object Number: 10783  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.

  13. Gently pinch the retaining clip.

  14. Object Number: 10930  Size: SH

    Important: The Electronic Spark Control module will be reused in the replacement VCM, carefully set the Knock Sensor Module aside in an area where it will not be damaged.

  15. 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 service number.

Steps 1-3 are only necessary for a replacement VCM installation.


    Object Number: 10930  Size: SH
  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

    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 access cover on the VCM.
  6. Tighten
    Tighten the access cover screws to 5.0N·m(44 lb in).


    Object Number: 279288  Size: SH
  7. Install the VCM in the VCM bracket.

  8. Object Number: 234989  Size: SH
  9. Install the VCM and bracket to the VCM support.
  10. Tighten
    Tighten the access cover screws to 10.0N·m(90 lb in).


    Object Number: 234993  Size: SH
  11. Install the harness connectors to the VCM.
  12. Connect the negative battery cable.
  13. 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 instructions for VCM programming.
  4. If the VCM fails to program, perform the following steps:
  5. • Check all the VCM connections.
    • Check the Techline terminal and equipment for the latest software version.
    • Program the VCM. If the programming fails again, replace the VCM.
  6. Perform the CKP System Variation Learn Procedure. Refer to Crankshaft Position System Variation Learn .
  7. For a functional check, perform the Powertrain On-Board Diagnostic (OBD) System Check. Refer to Powertrain On Board Diagnostic (OBD) System Check .