Rear Air Brake Relay Valve Replacement Standard

1. Apply the parking brake.
2. Block the wheels.
3. Drain all the reservoirs. Refer to Draining Reservoirs .
4. Disconnect the air lines from the valve.

Tag or label the air lines for installation.




5. Remove the bolts (3).
6. Remove the washers (1).
7. Remove the nuts (9).
8. Remove the relay valve (5).
9. Inspect the air lines for damage, kinks or wear. Repair the air lines as needed.

1. Connect the relay valve (5) to the bracket (2).
2. Install the bolts (3).
3. Install the washers (1).

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.

4. Install the nuts (9).

Tighten
Tighten the relay valve nuts (9) to 45 N·m (33 lb ft).

5. Install the air lines.
6. Start the engine.
7. Check for air leaks using a soap solution.
8. Check for proper operation.
9. Remove the wheel blocks.

Rear Air Brake Relay Valve Replacement Double Check

1. Apply the parking brake.
2. Block the wheels.
3. Drain all the reservoirs. Refer to Draining Reservoirs .
4. Disconnect the air lines from the relay valve. Tag or label the air lines for installation.



5. Remove the bolts (10).
6. Remove the washers (8).
7. Remove the nuts (7).
8. Remove the relay valve with double check (3) from the frame.
9. Inspect the air lines for damage, kinks or wear.

Repair the lines as needed.

1. Install the relay valve with double check (3).
2. Install the bolts (10).
3. Install the washers (8).

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.

4. Install the nuts (7).

Tighten
Tighten the relay valve with double check nuts (7) to 45 N·m (33 lb ft).

5. Install the air lines.
6. Start the engine.
7. Charge the system air pressure to the governor cut-out point.
8. Stop the engine.
9. Check for air leaks using a soap solution.
10. Check for proper operation.
11. Remove the wheel blocks.

Rear Air Brake Relay Valve Replacement Proportioning

1. Apply the parking brake.
2. Block the wheels.
3. Drain all the reservoirs. Refer to Draining Reservoirs .
4. Disconnect the air lines from the valve.
5. Tag or label the air lines for later installation.



6. Remove the bolts (1).
7. Remove the washers (8).
8. Remove the nuts (9).
9. Remove the proportioning relay valve (3).
10. Inspect the air lines for cracks, kinks or wear. Repair the lines as needed.

1. Install the proportioning relay valve (3).
2. Install the bolts (1).
3. Install the washers (8).

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.

4. Install the nuts (9).

Tighten
Tighten the proportioning relay valve nuts (9) to 45 N·m (33 lb ft).

5. Install the air lines.
6. Start the engine.
7. Charge the system air pressure to the governor cut-out point.
8. Stop the engine.
9. Check for leaks using a soap solution.
10. Check for proper operation.
11. Remove the wheel blocks.