For 1990-2009 cars

1. Block the wheels.
2. Start the engine.
3. Charge the system to the air compressor governor cut-out point.
4. Stop the engine.
5. Apply a soap solution to cover the inflation valve.
6. If any bubbles appear, install the valve core finger tightly and inspect the valve for leaks.
7. If any leakage is still present, replace or overhaul the inflation valve. Refer to Front Axle Service Reservoir Air Supply Valve Replacement or Air Brake System Description and Operation .
8. Remove the wheel blocks.