GM Service Manual Online
For 1990-2009 cars only

Important: Do not substitute a PCM from another vehicle for diagnosis. The PCM will not recognize the Vehicle Theft Deterrent password from the BCM. The PCM disables the fuel, and the PCM stores DTC P1631 into history.

Important: The following must be performed anytime the PCM is replaced:

  1. Programming of the EEPROM
  2. The Idle Learn Procedure. Refer to Idle Learn .
  3. The Functional Check

The following must be performed anytime the PCM loses power or is reprogrammed:

  1. The Idle Learn Procedure. Refer to Idle Learn .
  2. The Functional Check

Removal Procedure

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

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM module connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM.

    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. Important: The ignition should always be OFF when installing or removing the PCM/TAC module connectors.

  3. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  4. Remove the right front tire and wheel assembly. Refer to Wheel Removal.

  5. Object Number: 66265  Size: SH
  6. Remove the wheelhouse filler panel. Refer to Wheelhouse Filler Replacement.

  7. Object Number: 95554  Size: SH
  8. Remove the fasteners retaining the Throttle Actuator Control (TAC) module to the PCM mounting bracket.
  9. Remove the electrical connectors from the TAC module.
  10. Remove the TAC module from the vehicle.

  11. Object Number: 50740  Size: SH

    Important:: The remaining steps are for the PCM replacement.

  12. Disconnect the PCM electrical harness connectors.
  13. Loosen but do not remove the PCM rear retaining fastener. Use the rear retaining fastener as an anchor for the outer bracket.
  14. Remove the front retaining fastener from the PCM.
  15. Reposition the PCM outer bracket.
  16. Remove the PCM from the bracket and the vehicle.

Installation Procedure


    Object Number: 50754  Size: SH
  1. Install the PCM to the PCM rear bracket.
  2. Position the PCM front bracket.
  3. 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.

  4. Install the PCM front retaining fastener.
  5. Tighten
    Tighten the PCM retaining fasteners to 8 N·m (70 lb in).


    Object Number: 50740  Size: SH
  6. Connect the electrical connectors to the PCM.

  7. Object Number: 95554  Size: SH
  8. Connect the electrical connectors to the TAC module.
  9. Align the hole in the rear mounting tab of the TAC module to the corresponding hole in the PCM mounting bracket. Position the TAC module below the rear mounting tab for greater clearance in order to install the rear retaining fastener.
  10. Install the TAC module rear retaining fastener.
  11. Align the front mounting holes of the TAC module.
  12. 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.

  13. Install the TAC module front retaining fasteners.
  14. Tighten
    Tighten the TAC module retaining fasteners to 1.9 N·m (17 lb in).


    Object Number: 66265  Size: SH
  15. Install the wheelhouse filler panel. Refer to Wheelhouse Filler Replacement.
  16. Install the right front tire and wheel assembly. Refer to Wheel Removal.
  17. Lower the vehicle.
  18. Program the EEPROM if a new PCM is being installed.

EEPROM Programming

Setup

  1. Ensure that the following conditions have been met:
  2. • The battery is fully charged.
    • The scan tool cable connection at the DLC is secure.

    Object Number: 369961  Size: LH
  3. Turn OFF the ignition.
  4. Remove the passenger side (right side of vehicle) floor access panel.
  5. Remove the splice pack/star connector shorting bars from both splice pack/star connectors (2 and 3). It may be necessary to remove the splice pack/star connectors (2 and 3) from the mounting positions.
  6. Install the Star Connector cable #1 from the J 42236 to the 12 pin splice pack connector (3). This is the connector with 8 or 9 wires.
  7. Install the Star Connector cable #2 from the J 42236 to the 12 pin splice pack (2). This is the connector with 4 wires.
  8. Select Star Connector #1 on the J 42236 toggle switch.
  9. Select position B on the J 42236 .
  10. Turn ON the ignition leaving the engine OFF.
  11. Important: Perform the theft deterrent password learn procedure if a new PCM is installed. Refer to DTC P1631 Theft Deterrent Password Incorrect .

  12. Program the PCM using the latest software matching the vehicle. Refer to the Techline terminal/equipment users instructions.
  13. If the PCM fails to program, proceed as follows:
  14. • Ensure that all PCM connections are OK.
    • Ensure that all connections at the Data Bus Diagnostic Switch Box and splice packs are OK.
    • Ensure the proper settings on the Data Bus Diagnostic Switch Box are OK.
    • Check the Techline terminal/equipment for the latest software version.
    • Attempt to program the PCM. Replace the PCM if the PCM still cannot be programmed properly.
    • Program the replacement PCM.
  15. Perform the theft deterrent password learn procedure if a new PCM is installed. Refer to DTC P1631 Theft Deterrent Password Incorrect .
  16. Perform the Idle Learn Procedure. Refer to Idle Learn .

Functional Check

  1. Clear the Diagnostic Trouble Codes (DTCs).
  2. Perform the On-Board Diagnostic System Check.
  3. Start the engine and run for 1 minute.
  4. Scan for DTCs using the scan tool.