For 1990-2009 cars

1. Block the wheels.
2. Start the engine.
3. Charge the system air pressure to the governor cut-out point.
4. Apply the system park control.
5. Check that the spring brake chamber assemblies apply promptly.
6. Install a test air pressure gage in the delivery port air line.
7. Release the system park control.
8. Check that the spring brake chamber assemblies release fully.
9. Check that the test gage pressure reading is approximately 448 kPa (65 psi).
10. Replace the valve if the pressure reading is off more than 35 kPa (5 psi).
11. Apply the system park control.
12. Check that the test gauge reading falls to zero promptly.
13. 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 .
14. Release the system park control.
15. Turn off the engine.
16. Completely drain the air from the rear service reservoir.
17. Have an assistant apply and release the brake pedal repeatedly.
18. Check that the pressure reading decreases each time the brake pedal is applied.

As the pressure drops, the spring brake chamber assembly pushrod should move less and less until it no longer stays released.

19. Remove the wheel blocks.