For 1990-2009 cars only
- Block the wheels.
- Apply the parking brake.
- Start the engine.
- Charge the system air pressure to the governor cut-out point.
- Have an assistant apply the brake pedal.
- Coat the exhaust port (5) with a soap solution.
- Check that leakage is less than a 25 mm (1 in) bubble in three seconds.
- Repair or replace the valve (1) if the leakage exceeds these specifications.
- Coat the cover and the mating area between the top and the bottom of the valve (4) with a soap solution.
- Check for leakage.
- If any bubbles appear, replace the valve (4).
- Remove the wheel blocks.
