Differential Lock Control Valve Replacement for GMC Truck TopKick C-Series (Conventional) C6/C7/C8 2003

1. Apply the parking brake.
2. Block the wheels.
3. Drain all of the air reservoirs. Refer to Air Brake Reservoir Draining .

Important: Tag the air lines for later installation.




4. Remove the air lines at the differential lock control valve. Refer to Hose and Line Replacement - Nylon Push-In Type Fitting .
5. Remove the differential lock control valve bolts.
6. Remove the differential lock control valve (3) from the side rail (2).
7. Inspect the air lines for the following conditions:

•

Damage

•

Kinks

•

Wear

8. Repair or replace the air lines as needed. Refer to Hose and Line Replacement - Nylon Push-In Type Fitting .

1. Install the differential lock control valve (3) to the side rail (2).

Notice: Refer to Fastener Notice in the Preface section.

2. Install the differential lock control valve bolts.

Torque
Torque to 16 N·m (12 lb ft).

3. Install the air lines at the differential lock control valve (3). Refer to Hose and Line Replacement - Nylon Push-In Type Fitting .
4. Start the engine. Charge the system to the air compressor governor cutout point.
5. Stop the engine.
6. Inspect for air leaks using a soap solution.
7. Verify proper operation of the differential lock.
8. Remove the wheel blocks.