GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2007 🢒 STS 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Engine Control Module Replacement

Removal Procedure

Notice: 

   • Turn the ignition OFF when installing or removing the control module connectors and disconnecting or reconnecting the power to the control module (battery cable, powertrain control module (PCM)/engine control module (ECM)/transaxle control module (TCM) pigtail, control module fuse, jumper cables, etc.) in order to prevent internal control module damage.
   • 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 vehicle battery.
   • In order to prevent any possible electrostatic discharge damage to the control module, do no touch the connector pins or the soldered components on the circuit board.
   • Remove any debris from around the control module connector surfaces before servicing the control module. Inspect the control module connector gaskets when diagnosing or replacing the control module. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the control module.
   • The replacement control module must be programmed.

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 percent. If the replacement module is not programmed with the remaining engine oil life, the engine oil will need to be changed at 5 000 km (3,000 mi) from the last engine oil change.

Important: It is necessary to record the remaining automatic transmission fluid life. If the replacement module is not programed with the remaining automatic transmission fluid life, the automatic transmission fluid life will default to 100 percent. If the replacement module is not programmed with the remaining automatic transmission fluid life, the automatic transmission fluid will need to be changed at 83 000 km (50,000 mi) from the last automatic transmission fluid change.


    Object Number: 1847921 Size: SH
  1. Turn the ignition OFF.
  2. Using a scan tool, retrieve the percentage of remaining engine oil and automatic transmission fluid life. Record the remaining engine oil and automatic transmission fluid life.
  3. Remove the front compartment sight shield. Refer to Front Compartment Sight Shields Replacement .

    4. Important: Ensure that there is no main relay circuit voltage (ECM/TCM/IGN Fuse).

  4. Use a DVOM in order to measure the main relay circuit voltage at the ECM/TCM/IGN fuse in the underhood fuse block. Refer to Electrical Center Identification Views .
  5. Use a DVOM in order to measure the main relay circuit voltage at the TCM/BATT fuse in the underhood fuse block. Refer to Electrical Center Identification Views .
  6. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  7. Remove the TCM/BATT fuse from the underhood fuse block. Refer to Electrical Center Identification Views .
  8. Remove the ECM/TCM/IGN fuse from the underhood fuse block. Refer to Electrical Center Identification Views .

    9. Notice: In order to prevent any possible electrostatic discharge damage to the ECM, do not touch the connector pins.

  9. Unlock and disconnect the front engine wiring harness electrical connector from the ECM.

    10. Object Number: 1847922 Size: SH
  10. Unlock and disconnect the rear engine wiring harness electrical connector from the ECM.

    11. Object Number: 1847923 Size: SH
  11. Release the locking tabs (1) and remove the ECM from the ECM bracket.

    12. Object Number: 1847924 Size: SH
  12. If replacing the ECM bracket perform the following steps:
  13. Using a small flat-bladed tool, depress the locking tabs on the ECM bracket.

    14. Object Number: 1847925 Size: SH
  14. Remove the ECM bracket.

Installation Procedure

    Object Number: 1847925 Size: SH
  1. If replacing the ECM bracket perform the following steps, other wise proceed to step 3.
  2. Position and install the ECM bracket, ensure that the bracket engages the locking tabs.

    3. Object Number: 1847923 Size: SH
  3. Position and install the ECM to the ECM bracket, ensure that the ECM engages to locking tabs (1).

    4. Object Number: 1847922 Size: SH

    Notice: In order to prevent any possible electrostatic discharge damage to the ECM, do not touch the connector pins.

  4. Connect and lock the rear engine wiring harness electrical connector to the ECM.

    5. Object Number: 1847921 Size: SH
  5. Connect and lock the front engine wiring harness electrical connector to the ECM.
  6. Install the ECM/TCM/IGN fuse to the underhood fuse block. Refer to Electrical Center Identification Views .
  7. Install the TCM/BATT fuse to the underhood fuse block. Refer to Electrical Center Identification Views .
  8. Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection .
  9. Install the front compartment sight shield. Refer to Front Compartment Sight Shields Replacement .
  10. Program the ECM. Refer to Control Module References .
  11. Turn OFF the ignition for a least 5 seconds after the programming event is complete.