For 1990-2009 cars only
- Block the wheels.
- Start the engine.
- Charge the air system to the air compressor governor cut-out point.
- Stop the engine.
- Release the brake pedal.
- Inspect the exhaust port and the area around the exhaust port retaining ring for any air leakage. The air leakage should be less than a 25.4 mm (1 in) bubble in three seconds.
- Inspect the outside of the valve where the cover joins the valve body for any air leakage.
- Remove the wheel blocks.
If the air leakage is excessive, overhaul or replace the relay valve.
If any bubbles appear, indicating leakage, overhaul or replace the relay valve.
