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: 239317  Size: SH
  3. Remove the VCM bracket bolts and remove the VCM and bracket from the VCM support.
  4. Remove the electrical connectors from the VCM.

  5. Object Number: 234995  Size: SH
  6. Pry the VCM bracket lock tabs and remove the VCM from the bracket.

  7. Object Number: 279289  Size: SH

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

  8. Remove the Knock Sensor Module access cover.

  9. Object Number: 10783  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.

  10. Remove the Knock Sensor Module by gently squeezing the lock tabs together.

Installation Procedure

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


    Object Number: 279302  Size: SH
  1. Align the notches of the PROM / Electronic Spark Control Module with the notches in the PROM socket.

  2. Object Number: 10930  Size: SH

    Important: Press only on the ends of the Knock Sensor Module. Gently press on the module until it is firmly seated in the socket. Listen for the click.

  3. Install the Knock Sensor Module in the module socket.

  4. Object Number: 279289  Size: SH
  5. Install the access cover on the VCM.
  6. Install the access cover screws.
  7. Tighten
    Tighten the access cover screws to 4.8N·m(42 lb in).

  8. Install the VCM to the VCM bracket.
  9. Install the connectors to the VCM.

  10. Object Number: 239317  Size: SH
  11. Install the VCM bracket to the VCM support.
  12. Connect the negative battery cable.
  13. Proceed to the VCM programming.

VCM Programming

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