For 1990-2009 cars only
- Block the wheels.
- Start the engine.
- Charge the system air pressure to the governor cut-out point.
- Apply the system park control.
- Check that the spring brake chamber assemblies apply promptly.
- Install a test air pressure gage in the delivery port air line.
- Release the system park control.
- Check that the spring brake chamber assemblies release fully.
- Check that the test gage pressure reading is approximately 448 kPa (65 psi).
- Replace the valve if the pressure reading is off more than 35 kPa (5 psi).
- Apply the system park control.
- Check that the test gage reading falls to zero promptly.
- If the gauge does not fall to zero, replace or overhaul the valve. Refer to Chassis Mount Air Brake Park Control Valve Replacement or Air Brake System Description and Operation .
- Release the system park control.
- Turn OFF the engine.
- Completely drain the air from the rear service reservoir.
- Have an assistant apply and release the brake pedal repeatedly.
- Check that the pressure reading decreases each time the brake pedal is applied.
- Remove the wheel blocks.
As the pressure drops, the spring brake chamber assembly pushrod should move less and less until it no longer stays released.
