Problem #1

Air Leak at Brake (Foot) Valve Exhaust Port with Service and Parking Brakes Released

Note: For air to leak at the Exhaust Port of any valve: The valve is bad or;
Tank pressure is getting to the Delivery Port from other components.

POSSIBLE CAUSES

Tractor Protection Valve
Trailer Components
Tractor Parking System Components Anti-Compound Valve (if equipped and depending on plumbing)
Spring Brake Control
Spring Brake Chambers
Brake (Foot) Valve

TRACTOR PROTECTION VALVE TESTS
Step #1

Pull Trailer Supply (red knob on dash). If leak continues, go to Step #6.
If leak stops, go to Step #2.

Step #2
Disconnect Glad Hands and connect to holder on tractor.
Push Trailer Supply. If exhaust Port of Foot Valve leaks, replace Tractor Protection Valve.
If Exhaust Port of Foot Valve does not leak, problem is in Trailer. Go to Step #3.

TRAILER COMPONENT TESTS
Step #3

Connect Glad Hands.
Release Trailer Brakes.
Disconnect Control Line from Service Port of Relay. If leak continues, go to Step #4.
If leak stops, go to Step #5.

Step #4
Disconnect Anti-Compound Line (if equipped).
Leak at Exhaust Port of Foot Valve should stop. Replace Trailer Spring Brake Valve.

Step #5
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 Chamber, replace Spring Brake Chamber.
With all Delivery Lines disconnected and leak continues, replace Relay Valve.

TRACTOR PARKING SYSTEM COMPONENT TESTS
Step #6

1. Pull Park Control. If leak continues, go to Step #9.
If leak stops, go to Step #7.

ANTI-COMPOUND VALVE TEST
Step #7

Release Park Brakes.
Disconnect Anti-Compound Line. If leak stops, replace Anti-Compound Line.
If leak continues, go to Step #8.
If not equipped with Spring Brake Control Valve, go to Step #9.

SPRING BRAKE CONTROL VALVE TEST
Step #8

Disconnect Delivery Line from Secondary Signal Line. If leak stops, replace Spring Brake Control Valve.
If leak continues, go to Step #9.

SPRING BRAKE CHAMBER TEST
Step #9

Disconnect Delivery Line to Service Side of Spring Brake Chambers, one at a time. If there is a leak out of the Service side of the Spring Brake Chamber, replace Spring Brake Chamber (Remember, there may be more than one bad chamber).

BRAKE (FOOT) VALVE TEST
Step #10

After completing Steps #1 through #9 and leak continues, disconnect all Delivery Lines. If leak continues, replace Brake (Foot) valve.
If leak stops, recheck Steps #1 through #9.

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