GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2001 🢒 Isuzu T-Series (Truck Line C) 🢒 Brakes 🢒 Air Brakes 🢒 Air Brake Double Check Valve Operational Check
  1. If the vehicle has trailer provisions, connect the vehicle to a known operating trailer.
  2. Block the vehicle wheels.
  3. Start the engine.
  4. Charge the air system to the governor cut-out point.

    5. Object Number: 227886 Size: SH
  5. Push in the park control knob and the trailer air supply knob, if equipped.
  6. Turn off the engine.
  7. Drain the rear service reservoir.
  8. Verify the following items:
    9. • The park control knob and the trailer air supply knob should remain in the applied position and not pop out.
    • The spring brake chamber assemblies must remain in the released position. If the assemblies are not in the same position, overhaul or replace the double check valve.
    • For models with trailer provisions the brake pedal should apply the trailer service brakes. If the brake pedal does not apply the trailer service brakes, check the trailer air brake control valve. If it is operational, overhaul or replace the double check valve.
  9. Start the engine and charge the air system to the air compressor governor cut-out point.
  10. Push in the park control knob and the trailer air supply knob.
  11. Turn off the engine.
  12. Drain the front service air reservoir.
  13. Verify that the following items in step 8 are functioning normally. If one of the items does not function properly, overhaul or replace the double check valve.
  14. Start the engine.
  15. Charge the air system to the air compressor governor cut-out point.
  16. Check for proper brake operation.
  17. Stop the engine.
  18. Set the parking brake.
  19. Remove the wheel blocks.