Ive had a hard and high pedal for quite sometime now and i checked it yesterday. Sounds like a booster, however, checked it and its not. Thats good and so is the master cylinder. So i jacked the car up and realized that when i step on the brake, the rear wheels just keep spinning. Like no restriction in them whatsoever. I know that the module under hood controls this but that part is like 1000 bucks. Is it possible that like the valve is stuck down and that it is causing for there to be no pressure to my rear brakes? I also have a ABS Inop light so if anyone can help me with these, that would be great.

I have a 94 Formula


Thank You

Rrealized that I have no service manual and trying to answer by memory for a safety related item is risky.

Here's my thoughts...there should be a trip switch on the brake bias block located under the master cylinder. If there is, push the trip switch on the block. If necessary, bleed the brakes.

If there is no trip switch on the bias block, then take it to the dealer and have them fix it. This is too dangerous to leave unfixed, not to mention that the front brakes are being stressed and overheated.

This might not be a fault of the anti-lock system or the anti-lock brake module located under the dash. It should be a check valve fault within the bias block. It is possible that the within the anti-lock motor, the cylinders have to be "rehomed". This is tricky and is best done following the instructions in the svc manual. In other words, take it to the dealer and not Schlock's Auto Parts around the corner or read my posting following this, try it and if no success take it to the dealer. The ABS INOP light, by itself, is a code that tells what is wrong or what has failed. If the Lo TRACl light (is that the correct name?) also comes on, then something else is wrong, both lights together are a code. You need the service manual or maybe somebody could look this up for you to tell what has failed.

Somewhere in this forums archives, is the answer to all of this. I published it several years ago for the 94 and I'm gonna try and find it.

Here, found this in the archives from way back in 2003 (one of my postings under the name Charles), will keep looking, maybe I can find some more info. Maybe it will help and maybe not:

Yes, it could cause the problem with the rear brakes, or maybe not. Happened to me once. The problem might be in the "homing" of the cylinders in the ABS motor. There are three of them (I think, been awhile since I looked at this thing). The cylinders must be rehomed by the Tech 1 tool, or it can be done manually.

Here's what I would do first. Check the rear brakes and make sure that the sliding pins are lubricated and the pads aren't hanging up.

Next, rehome the ABS motors, this is done with the Tech 1. Or do this:

1. Remove foot from brake pedal
2. Start engine and allow it to run for at least 10 seconds.
3. If the ABS INOP lamp turned ON and stayed ON after about 10 seconds, the TECH 1 must be used to diagnose the problem--in other words stop everything.
4. If the ABS INOP lamp turned ON for approx 3 seconds, then turned OFF, and stayed OFF, turn the ignition to OFF
5. Repeat steps 1 thru 4 one more time.

Now the entire brake system can be bled:

First: bleed the modulator: Apply moderate pressure to the brakes and slowly open the rear most bleeder valve, shut the valve, release the brakes. Do it again, until no air bubbles come out, then do the front bleeder the same way.

Bleed the brakes in this order: Right rear, left rear, right front, left front.

Brake Pressure Differential Warning switch. If this ever comes on, or you have seen it come on, then with the key on, engine off, press on the brakes about as hard as you can --think of a force of 450 psi! That might help.

After all this, and nothing works, it needs to go into the dealer. You are right, the rear brakes shouldn't do that. Could be a problem in the EBCM, the hydraulic pumps, the Combination Valve Assembly (both the proportioning valve and the differential pressure warning assembly) or something as simple as incorrect bleeding (that is my guess).

If you have never seen a warning light of any sort, my guess is that it is a simple fix, but the dealer should be doing it. That Tech 1 tool (reads the codes and does repairs to the hydraulic motors), is really needed and it can't be bought or borrowed at the local Pep Boys.


--------------------

Charles (94 Formula T-Top, green/gray leather, 6spd, some stock parts remaining, some even work).

My disclaimer: Any information that is furnished by me, is sometimes the result of endless hours of frustrating research and it might come from recognized authorities on the subject that I don't know. Sometimes it is also my personal opinion. Remember, your results may vary...mine certainly do.

Driving a Mustang is like wearing the wrong size shoe, so why bother.

well im pretty sure that its the brake pressure modulator valve (BPMV). However, this part from the dealership is like 1k and i dont feel like spending that much on a brake part. I was wondering if the firebirds and camaros with 6 cylinders (drum brakes) have the same valve on top? or if any other car has the same valve on top so i can locate one from a junkyard or something.

Yeow! Your best bet would be to search the junkyards. My guess is that the valve is unique to the Firebird and Camaro with rear disc brakes and not common to other cars as the biasing would be different.

Did you look for the little pressure switch on the valve? I cannot remember if there was one or not. Also, you should try the various methods for bleeding the brakes and unlocking the pressure that is built up before doing anything else. One way to do this, open the right rear brake bleed screw and have someone push down on the brake pedal, then do the left side with the button on the bias valve pushed in. Be careful to not allow air to be sucked inside. Then go thru the series of steps that are in my last posting, those are right out of the service manual. The ABS motor must have its cylinders rehomed after bleeding. Ideally, this should be done with the scan tool which activates the cylinders.

Alternatively, I would check with other dealers. I really think that something is out of whack, but not broken, and a correct bleeding sequence must be done to fix it, but parts do not need to be replaced. You will need to read the factory service manual.