GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 CTS 🢒 Preface 🢒 Cautions and Notices 🢒 Engine Control Module Replacement

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.

Removal Procedure

    Object Number: 1285259 Size: SH
  1. Turn the ignition OFF.
  2. Using a scan tool, retrieve the percentage of remaining engine oil and the remaining automatic transmission fluid life. Record the remaining engine oil and the remaining automatic transmission fluid life.

    3. Important: Ensure that there is no main relay circuit voltage (ECM Fuse).

  3. Use a DVOM in order to measure the main relay circuit voltage at the ECM fuse in the underhood fuse block. Refer to Electrical Center Identification Views .
  4. Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection .
  5. Remove the ECM fuse in the underhood fuse block. Refer to Electrical Center Identification Views .
  6. Remove the TCM/IPC fuse in the underhood fuse block. Refer to Electrical Center Identification Views .
  7. Remove the ECM/TCM fuse in the underhood fuse block. Refer to Electrical Center Identification Views .
  8. Unlock the chassis side (upper) ECM electrical connector.
    9. 8.1. Depress the ECM electrical connector lever lock (1).
    8.2. Simultaneously rotate the ECM connector clamp lever and depress the lock slide (2).

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


    Object Number: 1343429 Size: SH
  9. Remove the body side (upper) ECM connector.

    10. Object Number: 945720 Size: SH
  10. Unlock and remove the engine side (lower) ECM connector.

    11. Object Number: 1343434 Size: SH
  11. Remove the ECM redundant ground wire bolt (2) and wire from the ECM.

    12. Object Number: 887860 Size: SH
  12. Remove the ECM bolts.
  13. Remove the ECM.
  14. If you are replacing the ECM bracket, perform the following steps:

    15. Object Number: 945521 Size: SH
  15. Remove the electrical connector bracket bolt and bracket from the ECM bracket.

    16. Object Number: 1343434 Size: SH
  16. Remove the ground wire bolt (1) and wire from the ECM bracket.

    17. Object Number: 945513 Size: SH
  17. Remove the wire harness retainer bolt and retainer from the side of the ECM bracket.

    18. Object Number: 887861 Size: SH
  18. Remove the ECM bracket bolts (2 and 3).
  19. Remove the ECM bracket  (1).

Installation Procedure

    Object Number: 887861 Size: SH
  1. Install the ECM bracket (1).

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

  2. Install the ECM bracket bolts (2 and 3).

    3. Tighten

    1. Tighten the ECM bracket to cylinder head bolts (2) to 10 N·m (89 lb in).
    2. Tighten the ECM bracket to engine front cover bolt (3) to 23 N·m (17 lb ft).

    Object Number: 945513 Size: SH
  3. Install the wire harness retainer and bolt (2) to the side of the ECM bracket.

    4. Tighten
    Tighten the bolt to 23 N·m (17 lb ft).


    Object Number: 945521 Size: SH
  4. Install the electrical connector bracket and bolt to the ECM bracket.

    5. Tighten
    Tighten the bolt to 10 N·m (89 lb in).


    Object Number: 1343434 Size: SH
  5. Install the wiring harness ground wire and bolt (1) to the ECM bracket.

    6. Tighten
    Tighten the bolt 10 N·m (89 lb in).


    Object Number: 887860 Size: SH

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

  6. Install the ECM.
  7. Install the ECM bolts.

    8. Tighten
    Tighten the bolts to 10 N·m (89 lb in).


    Object Number: 1343434 Size: SH
  8. Install the ECM redundant ground and bolt  (2) to the ECM.

    9. Tighten
    Tighten the bolt to 5 N·m (44 lb in).


    Object Number: 945720 Size: SH
  9. Install the engine side (lower) ECM connector.

    10. Object Number: 1343429 Size: SH
  10. Install the body side (upper) ECM connector.
  11. Install the ECM/TCM fuse in the underhood fuse block. Refer to Electrical Center Identification Views .
  12. Install the TCM/IPC fuse in the underhood fuse block. Refer to Electrical Center Identification Views .
  13. Install the ECM fuse in the underhood fuse block. Refer to Electrical Center Identification Views .
  14. Connect the battery negative cable to the battery. Refer to Battery Negative Cable Disconnection and Connection .
  15. Program the ECM. Refer to Control Module References .
  16. Turn OFF the ignition for at least 5 seconds after the programming event is complete.