For 1990-2009 cars

1. Start the engine.
2. Charge the system air pressure to the governor cut-out point.
3. Apply a soap solution to cover the valve.
4. Verify that no leakage occurs. If bubbles appear, install the valve core finger tightly.
5. Check for leaks. If air leakage is still present, replace or overhaul the valve. Refer to Front Axle Service Reservoir Air Supply Valve Replacement or Air Brake System Description and Operation .