GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Chevrolet C-Series Medium Duty Truck B7 🢒 Brakes 🢒 Air Brakes 🢒 Air Brake System Leak Test
  1. Inspect all tubing for kinks or dents.
  2. Inspect all hoses for signs of wear, drying out, or overheating.
  3. Inspect the suspension of all tubing. The tubing must be supported in order to eliminate vibration.
  4. Inspect the suspension of all of the hoses. Position the hoses so that the hoses do not abrade or are subjected to too much heat.
  5. Apply the parking brake.
  6. Start the engine.
  7. Charge the air system to the governor cut-out point.
  8. Stop the engine.
  9. Apply and release the service brakes.
  10. Check the air leakage.
    11. • Check that the dual air pressure gauge on the vehicles without trailer controls does not drop more than 28 kPa (4 psi) in 2 minutes.
    • Check that the dual air pressure gauge on the vehicles with trailer controls does not drop more than 41 kPa (6 psi) in 2 minutes.
    • If the dual air pressure gauge reading drops more than specified, check for leaks at the air line connections, the application valve, the trailer control valve, the relay valve, the park brake control valve, the governor,and other parts on the supply side of the application valve.
  11. Start the engine and charge the system to the governor cut-out point.
  12. Stop the engine.
  13. Firmly apply and hold the brakes.
  14. Check the air leakage using the following procedure:
    15. • If the air pressure drops 10 percent or more, check the air foundation brake adjustment at each wheel or too much lining and brake drum wear. Refer to Air Drum Brake Adjustment .
    • Check that the dual air pressure gauge on the vehicles without trailer controls does not drop more than 41 kPa (6 psi) in 2 minutes.
    • Check that the dual air pressure gauge on the vehicles with trailer controls does not drop more than 55 kPa (8 psi) in 2 minutes.
    • If the dual air gauge reading drops more than specified, test for leaks at the air line connections. Double check the valves, the quick release valve, the relay valve, and the other parts on the delivery side of the application valve.
    • Start the engine.
    • Charge the air system to the governor cut-out point.
    • Stop the engine.