GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

Notice: Check the resistance values of all PCM relays, solenoids, and other output controls before replacing or substituting the Powertrain Control Module (PCM). Check all the sensor wiring and the PCM output control circuits for a short to ground before replacing or substituting the PCM. Perform all circuit repairs or malfunctioning component part replacements before installing a replacement or substitute PCM. This will prevent damage to the replacement or substitute PCM.

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.

Notice: Turn the ignition OFF when installing or removing the PCM connectors and disconnecting or reconnecting the power to the PCM (battery cable, PCM pigtail, PCM fuse, jumper cables, etc.) in order to prevent internal PCM damage.

Important: Service of the engine control module (ECM) consists of complete replacement of the PCM. There are no serviceable parts, such as Programmable Read Only Memory (PROM) or Erasable Programmable Read Only Memory (EPROM) to replace inside the ECM. If the ECM is determined to be faulty, it is to be replaced as a complete assembly.

Important:  When replacing the production ECM with a service ECM, it is important to transfer the broadcast code and production ECM number to the service ECM label. This will allow for positive identification of the ECM throughout the service life of the vehicle.


    Object Number: 55232  Size: SH

    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. Disconnect the ECM electrical connectors (3).
  3. Remove the two bolts (2) securing the ECM, and TCM, if equipped with automatic transmission.
  4. Remove the ECM (1) from the vehicle.

Installation 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.

Notice: Turn the ignition OFF when installing or removing the PCM connectors and disconnecting or reconnecting the power to the PCM (battery cable, PCM pigtail, PCM fuse, jumper cables, etc.) in order to prevent internal PCM damage.


    Object Number: 55232  Size: SH
  1. Transfer the plastic shield from the original ECM to the new ECM (convertible models).
  2. Secure the plastic shield to the ECM with the two screws.
  3. Connect the ECM electrical connectors (3).
  4. Install the ECM (1).
  5. Secure the ECM with the two bolts (2).
  6. Connect the negative battery cable.