GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2003 🢒 ION 🢒 Body and Accessories 🢒 Lighting Systems 🢒 Engine Control Module Replacement

Removal Procedure

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

Notice: Always turn the ignition off when installing or removing the ECM connectors in order to prevent damage to the components.

    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. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.

    3. Object Number: 873343 Size: SH
  3. Disconnect the small ECM harness connector (3) from the ECM.
  4. Remove the bolt retaining the large ECM connector to the ECM.
  5. Disconnect the large ECM harness connector (4) from the ECM.

    6. Object Number: 857196 Size: SH

    Notice: Control module damage may result when the metal case contacts battery voltage. DO NOT contact the control module metal case with battery voltage when servicing a control module, using battery booster cables or when charging the vehicles battery.

  6. Use the retaining tab to release the ECM from the underhood junction block bracket.

Installation Procedure

    Object Number: 857196 Size: SH

    Notice: Control module damage may result when the metal case contacts battery voltage. DO NOT contact the control module metal case with battery voltage when servicing a control module, using battery booster cables or when charging the vehicles battery.

  1. Use the retaining tab to secure the ECM, when installing the ECM to the underhood junction block bracket.

    2. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 873343 Size: SH
  2. Connect the large ECM harness connector (4) to the ECM.

    3. Tighten
    Tighten the bolt to 4 N·m (35 lb in).

  3. Connect the small ECM harness connector (3) to the ECM.
  4. Connect the negative Battery Cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
  5. Program the ECM. Refer to Service Programming System (SPS) in Programming.