GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2005 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Brakes 🢒 Air Brakes 🢒 Low Air Pressure Switch Operational Check
  1. Apply the parking brake.
  2. Drain all of the reservoirs. Refer to Draining Reservoirs .
  3. Start the engine and run the engine at a fast idle.
  4. Verify that the low pressure tone alarm is on.
    5. •  If the tone alarm is not on when first charging the system, test the brake warning system.
    •  For diagnosis of the brake warning system, refer to Brake Warning Alarm Inoperative.
  5. The low pressure tone alarm should turn off when the dual air pressure gauge indicates 470-510 kPa (68-74 psi).
    6. •  If the tone alarm does not turn off, test the brake warning system.
    •  For diagnosis of the brake warning system, refer to Brake Warning Alarm Always On.