For 1990-2009 cars only
- Apply the vehicle parking brake.
- Drain all the reservoirs. Refer to Air Brake Reservoir Draining .
- Close all reservoir drain valves.
- Start the engine and charge the air system to the governor cut-out point.
- Verify that a discharge of air occurs at the air brake dryer exhaust port. This is the air brake dryer purge cycle. If the air brake does not cycle properly, check for air leaks in the air brake dryer system.
- Fan the service brakes to reduce system pressure to governor cut-in.
- Verify that system once again builds to full pressure and is followed by a discharge of air occurs at the air brake dryer exhaust port. If the air brake does not cycle properly, check for air leaks in the air brake dryer system.
- It is recommended that the total air system be tested for leakage to assure that the air dryer will not cycle excessively.
