Coolant Heater Replacement LL8

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



2. Remove the powertrain control module (PCM) retaining bolts (3) and nuts (6).
3. Remove the PCM mounting studs (5) and position the PCM out of the way.



4. Disconnect the engine coolant temperature (ECT) sensor electrical connector (1).

Notice: Refer to Fuel and Evaporative Emission Hose/Pipe Connection Cleaning Notice in the Preface section.




5. Disconnect the fuel feed (1) and fuel return (2) pipes from the fuel rail. Refer to Metal Collar Quick Connect Fitting Service .
6. Disconnect the integral clip (3) from the wire harness bracket.



7. Remove the engine wire harness bracket bolt.
8. Position the engine electrical wire harness bracket with wires attached out of the way.



9. Remove the coolant heater cord from the heater (2).




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

10. Remove the coolant heater from the block.

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.

Notice: Refer to Component Fastener Tightening Notice in the Preface section.




3. Install the coolant heater to the engine block.

Tighten
Tighten the coolant heater to 50 N·m (37 lb ft).




4. Install the coolant heater cord to the heater (2).
5. Properly position the engine electrical harness bracket to the intake manifold.

Notice: Refer to Fastener Notice in the Preface section.




6. Install the engine electrical harness bracket bolt.

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




7. Connect the integral clip (3) to the wire harness bracket.
8. Connect the fuel feed (1) and fuel return (2) pipes to the fuel rail. Refer to Metal Collar Quick Connect Fitting Service .



9. Connect the ECT sensor electrical connector (1).



10. Install the PCM mounting studs (5) to the intake manifold.

Tighten
Tighten the studs to 6 N·m (53 lb in).

11. Install the PCM (1) onto the studs (5).
12. Install the PCM retaining bolts (3).

Tighten
Tighten the bolts to 8 N·m (71 lb in).

13. Install the PCM retaining nuts (6).

Tighten
Tighten the nuts to 8 N·m (71 lb in).

14. Fill the cooling system. Refer to Cooling System Draining and Filling .

Coolant Heater Replacement LM4

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 in General Information.
3. Disconnect the coolant heater (1) electrical connector.




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

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

1. If re-using the old coolant heater, apply thread sealant GM P/N 12346004 (Canadian P/N 10953480), or equivalent to the threads.

Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

2. Install the coolant heater to the engine block.

Tighten
Tighten the coolant heater to 50 N·m (37 lb ft).





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.

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