- Apply the parking brake.
 
-  Block the wheels.
 
- Run the engine in order to fully charge all service reservoirs.
 
- Turn off the engine.
 
- Drain the air pressure from the supply reservoir. Refer to 
Air Brake Reservoir Draining.
 
- Disconnect the air line on the supply side of the valve (10).
 
- Apply a soap solution to the open supply port of the valve (10).
 
- Verify that leakage is less than a 25 mm (1 in) bubble in 5 seconds.
 
- If the leakage exceeds this amount, drain the air pressure from all reservoirs and replace the valve (10). Refer to 
Air Brake System Description and Operation.
 
- Connect the supply port air line.
 
- Start the engine.
 
- Charge the air system to the governor cut-out point.
 
- Connect the supply port air line.
 
- Check the brake operation.
 
- Remove the wheel blocks.