I'm resonding to a crazy old thread, but wanted to say this info helped.
Recently started having funny brake feel, would be Hard brake sometimes, then super squishy. Bled the brakes to find that no fluid was comming to the rear brakes. Then one day while driving the brake was in the squishy mood, and when stopping at a light, it went all the way to the floor and i felt and barely heard a click. Immediatly the brake light on the dash came on. From then on, anytime i moved forward just an inch, the light would come one and beep. Very annoying. Still hard sometimes, squishy others.
Had my mechanic check, and found the cylinder was bad. Once replaced, he said the prop valve might be bad, because althought brake was acting normal again, the light and beep were still on. He left the switch unplugged and the light was gone, but as soon as it was plugged back in, light and beep. Didn't want to pay $200 for the prop replacement so i left it.
So just found this thread, and went and tried resetting the valve switch by stomping on the peddle. Took a couple of really good panic - like stomps, with jeep running and in park. then finally heard and felt a tiny click in the pedal. Tested it out, and can now drive normal, with switch plugged in, and no light or beep, AND my breaks are back to normal. So all is good under the hood.
Its a jeep knock life