GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 GMC C-Series Medium Duty Truck B7 🢒 Brakes 🢒 Air Brakes 🢒 Air Brake Double Check Valve Operational Check
  1. Block the wheels.
  2. Start the engine.
  3. Charge the air system to the governor cut-out point.
  4. Apply the system park control.
  5. Turn off the engine.
  6. Drain the rear service reservoir.

    7. Object Number: 202535 Size: SH
  7. Check that the system park control remain applied and do not pop out.
  8. Check that the spring brake chamber assemblies remain in the unparked position.
  9. If the assemblies do not remain in the unparked position.
  10. Replace the double check valve (3) mounted on the side of the dual application valve (4). Refer to Air Brake Double Check Valve Replacement .
  11. If the brake pedal does not apply the service brakes,check the double check valve and the stoplamp switch. If the switch is operational.
  12. Replace the double check valve (3) mounted on the side of the dual application valve. Refer to Air Brake Double Check Valve Replacement .
  13. Start the engine.
  14. Charge the air system to the governor cut-out point.
  15. Check that the system park control.
  16. Turn off the engine.
  17. Drain the front service reservoir. Refer to Draining Reservoirs .
  18. Check that the items listed in steps 8, 9 and 10 function properly.
  19. If the items do not, replace the appropriate double check valve (3). Refer to Air Brake Double Check Valve Replacement .
  20. Start the engine.
  21. Charge the system.
  22. Check that the brakes operate properly.
  23. Set the parking brake.
  24. Remove the blocks from the wheels.