GM Service Manual Online
For 1990-2009 cars only
  1. Block the wheels.
  2. Have an assistant apply the brake pedal.

  3. Object Number: 202535  Size: SH
  4. Coat the exhaust port and the body of the application valve (4) with a soap solution.
  5. A 25 mm (1 in) bubble leakage in 3 seconds is permitted.
  6. Replace or overhaul the valve (4) if the leakage exceeds this amount. Refer to Air Brake Application Valve Replacement or Air Brake System Description and Operation .
  7. Check that the brakes are operating.
  8. Remove the wheel blocks.