Low Air Pressure Switch Diagnosis. GMC Truck GMC C-Series Medium Duty Truck B7 1999

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC C-Series Medium Duty Truck B7 🢒 Brakes 🢒 Air Brakes 🢒 Low Air Pressure Switch Diagnosis

Apply the parking brake.
Drain all of the reservoirs. Refer to Draining Reservoirs .
Start the engine.
Run the engine at a fast idle.
Verify that the low pressure tone alarm is on. If the tone alarm is not on when first charging the system, check the brake warning system.
The low pressure tone alarm should turn off when the dual air pressure gauge indicates 470-510 kPa (68-74 psi). If the tone alarm does not turn off, check the brake warning system.