Problem #2

POSSIBLE CAUSES
Spring Brake Chamber
Relay
Anti-Compound Valve (depending on plumbing)
SPRING BRAKE CHAMBER & RELAY TEST
Step #1

Pull Park Control Valve (yellow or blue knob on dash). If leak continues, go to Step #2.
If leak stops, go to Step #3.

Step #2

Replace Relay. Bad or dirty Inlet.

Step #3

Release Parking Brakes.
Disconnect Delivery Lines to Service Side of Spring Brake Chamber, one at a time. If there is a leak out of the Service Side of the Spring Brake Chamber, replace Chamber. (Remember, there may be more than one bad Chamber).
If Chambers do not leak, go to Step #4.

ANTI-COMPOUND VALVE TEST
Step #4

Disconnect service side of Anti-Compound Valve.
Release Parking Brakes.
If air leaks out of Anti-Compound Valve, replace valve.

Back to Air Brake Guide