GM Service Manual Online
For 1990-2009 cars only

Coolant Heater Replacement LL8

Removal Procedure

  1. Drain the engine coolant. Refer to Cooling System Draining and Filling.

  2. Object Number: 1284769  Size: SH
  3. Remove the powertrain control module (PCM) retaining bolts (3) and nuts (6).
  4. Remove the PCM mounting studs (5) and position the PCM out of the way.

  5. Object Number: 1288027  Size: SH
  6. Disconnect the engine coolant temperature (ECT) sensor electrical connector (1).
  7. Caution: Refer to Fuel and Evaporative Emission Hose/Pipe Connection Cleaning Caution in the Preface section.


    Object Number: 730718  Size: SH
  8. Disconnect the fuel feed (1) and fuel return (2) pipes from the fuel rail. Refer to Metal Collar Quick Connect Fitting Service.
  9. Disconnect the integral clip (3) from the wire harness bracket.

  10. Object Number: 1348786  Size: SH
  11. Remove the engine wire harness bracket bolt.
  12. Position the engine electrical wire harness bracket with wires attached out of the way.

  13. Object Number: 755428  Size: SH
  14. Remove the coolant heater cord from the heater (2).

  15. Object Number: 755435  Size: SH

    Note: Do not score the surface of the engine block hole when removing the coolant heater.

  16. Remove the coolant heater from the block.

Installation Procedure

  1. Remove any burrs, sealer, paint or other foreign material from the threads/sealing surface of the engine block and from the old coolant heater if the heater is to be reused.
  2. If reusing the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.
  3. Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 755435  Size: SH
  4. Install the coolant heater to the engine block and tighten to 50 N·m (37 lb ft).

  5. Object Number: 755428  Size: SH
  6. Install the coolant heater cord to the heater (2).
  7. Properly position the engine electrical harness bracket to the intake manifold.

  8. Object Number: 1348786  Size: SH
  9. Install the engine electrical harness bracket bolt and tighten to 10 N·m (89 lb in).

  10. Object Number: 730718  Size: SH
  11. Connect the integral clip (3) to the wire harness bracket.
  12. Connect the fuel feed (1) and fuel return (2) pipes to the fuel rail. Refer to Metal Collar Quick Connect Fitting Service.

  13. Object Number: 1288027  Size: SH
  14. Connect the ECT sensor electrical connector (1).

  15. Object Number: 1284769  Size: SH
  16. Install the PCM mounting studs (5) to the intake manifold and tighten to 6 N·m (53 lb in).
  17. Install the PCM (1) onto the studs (5).
  18. Install the PCM retaining bolts (3) and tighten to 8 N·m (71 lb in).
  19. Install the PCM retaining nuts (6) and tighten to 8 N·m (71 lb in).
  20. Fill the cooling system. Refer to Cooling System Draining and Filling.

Coolant Heater Replacement LH6, LS2

Removal Procedure


    Object Number: 898845  Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling.
  2. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle.
  3. Disconnect the coolant heater (1) electrical connector.

  4. Object Number: 898843  Size: SH

    Note: Do not score the surface of the engine block hole when removing the coolant heater.

  5. Remove the coolant heater from the engine block.
  6. Remove any burrs, sealer, paint or other rough spots.

Installation Procedure


    Object Number: 898843  Size: SH
  1. If re-using the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.
  2. Caution: Refer to Fastener Caution in the Preface section.

  3. Install the coolant heater to the engine block.
  4. Tighten
    Tighten the coolant heater to 50 N·m (37 lb ft).


    Object Number: 898845  Size: SH

    Notice: The heater cord must not touch the engine, hot pipes, manifold, or any moving parts. Route the cord to the left front of the engine compartment securing with tie straps as necessary to prevent damage.

  5. Connect the coolant heater (1) electrical connector.
  6. Lower the vehicle.
  7. Fill the cooling system. Refer to Cooling System Draining and Filling.