For 1990-2009 cars only
- Apply the parking brake.
- Start the engine.
- Charge the system air pressure to the governor cut-out point.
- Pull out the exposed end of the valve stem.
- Air should be expelled from the vent.
- Replace the safety valve (1) if the air is not expelled.
- Release the valve stem.
- Check that the air exhaust stops.
- Replace the safety valve (1) if the air does not stop.
