For 1990-2009 cars

### Removal Procedure

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

Important: Tag the air lines for later installation.

3. Remove the air lines at the differential lock pressure protection valve. Refer to Hose and Line Replacement - Nylon Push-In Type Fitting .
4. Remove the following components from the differential lock pressure protection valve:

• | The nuts

• | The washers

• | The bolts

5. Remove the differential lock pressure protection valve at the brake pedal bracket.
6. Inspect the air lines for the following conditions:

• | Damage

• | Kinks

• | Wear

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

### Installation Procedure

1. Install the differential lock pressure protection valve at the brake pedal bracket.

Notice: Refer to Fastener Notice in the Preface section.

2. Install the following components to the differential lock pressure protection valve:

• | The bolts

• | The washers

• | The nuts

Tighten
Tighten the differential lock pressure protection valve nuts to 12 N·m (106 lb in).

3. Install the air lines at the differential lock pressure protection valve. 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. Remove the wheel blocks.