brake light!

[90xj06]

:exclamatiok my brake light came on today while i was driving. the peddle went to the floor. so i checked my fluid. still full. so i check the rear brakes for air. nothing. and i did check the switch. and its is not the e-brake switch. so with some further checking i have found i have no back brakes. so i checked the reservoir and it had a small leaf in it. so i cleaned it out and replaced it with new fluid. still the light is on and the peddle will travel to the floor is repeated pumps. so i think its the proportioning valve. my question is what do you think and where can you get this valve? :smsoap:

[90xj06]

ok well i found how to turn off the light. but if im sitting at a light and ease off the brake and then reapply is will slowly sink to the floor. not loosing fluid so...why???

[90xj06]

ok well does no one know why???? is it the valve. booster. and id does not have ABS. i just don't want to go for a drive and loose my brakes running over a school full of kids.

[90xj06]

once again any thing. i cant bleed my back brakes so im assuming its the combonation valve.

[SS01XJ]

I had your symptoms on a car years ago(pedal to floor & no brakes), and it turned out to be a bad master cylinder.

Edit. No leaks either

HTH

[90xj06]

but it does still work. if you have your foot on the peddle occasionally it will sink to the floor. but it will still hold the jeep and the brakes still function. but if you push the peddle to the floor it will cause the warning light to come on.

[Eagle]

The warning light will ONLY come on if there is a pressure difference between the front and rear circuits. Such a pressure difference can be caused by a leak in either circuit, or by a faulty master cylinder that doesn't produce equal pressure to both circuits. If you somehow miraculously lost all pressure to both the front and the rear brakes simultaneously -- the light would never come on.

Q1. You said you "can't" bleed the rear brakes. Why not? If you have no rear brakes, the first thing you should do is bleed them.

Q2. What leads you to suspect that your problem may be the proportioning valve?

[90xj06]

well it was just a thought so today i went out to buy a master cylinder. i think i lost one of the circuits this making the rear brakes unbleedable. i figured it was the valve because the rear brakes don't work.

i wonder if the master cylinder was failing for a long time. the brakes never worked right when i got it. and the fluid looked contaminated. i was looking at the new gasket for the master and it was nice and had some "pockets" mine was huge. all stretched out.

[PosiDave]

master cylinder. if it were the booster you wouldn't be able to press the thing down without alot of force.

[90xj06]

o ya i know that. but i should have bought a booster too. mine is a little rusty.

[90xj06]

this thread was brought up in a pm and it was infact the master cylinder.

[xj4fun]

Highly probable your MC has an internal leak between the seals for the front and rear brakes.