GM Service Manual Online
For 1990-2009 cars only
Makes
🢒
GMC_Truck
🢒
2003
🢒
TopKick C-Series (Conventional) C4/C5
🢒
Brakes
🢒
Air Brakes
🢒 Trailer Brake Supply Valve Leakage Test
Block the wheels.
Start the engine.
Charge the system air pressure to the governor cut-out point.
Pull out the trailer air supply knob (3).
Pull out the system park knob (1).
Apply a soap solution to the exhaust vent and around the base of the trailer air supply knob (3).
Verify that leakage is less than a 25 mm (1 in) bubble in 5 seconds. If not, replace the valve. Refer to
Trailer Brake Supply Valve Replacement
or overhaul the valve. Refer to
Air Brake System Description and Operation
.
If the leakage exceeds these limitations, replace the valve. Refer to
Trailer Brake Supply Valve Replacement
or overhaul the valve. Refer to
Air Brake System Description and Operation
.
Push in the trailer air supply knob (3).
Apply a soap solution to the exhaust port.
Check that the leakage is less than a 25 mm (1 in) bubble in 5 seconds.
If the leakage exceeds these limitations, replace the valve. Refer to
Trailer Brake Supply Valve Replacement
or overhaul the valve. Refer to
Air Brake System Description and Operation
.
Set the parking brake.
Remove the wheel blocks.