I need help w/a brake problem

[Blue68]

Prop valves do stick. They are supposed to! If you loose the rear circuit, all pressure goes to the front, and the other way around, so the idea is you have some brakes at one end even if you have a catasrophic failure somewhere. Prop valves can also be un-stuck, but not always. If your prop valve has the brake light, and it still works, it should come on when this happens. In order to unstick (and this can occur when bleeding them) the valve, you open the circuit (bleeder) where you have pressure, the lack of pressure there will force the check valve the other way (toward the middle) and reset. Just don't try this with vacuum on the booster or the valve will flip the other way.

Good luck.