Anyone PLEASE HELP!!! A6 BRAKES
 

I have a 1999 A6 and the brakes have locked up twice, the only way to unlock them was to remove the vacuum line that feeds the master cylinder, I remove the hose from the (I think its a one-way valve) rear of the motor under the vacuum hose area and you can hear the air leak out and the brakes release? What the hell is causing this? is it that vacuum valve where the master cylinder gets its vacuum from? Please if anyone knows what or why this happens I would be forever greatful. Times are tough and I can't afford to take it anywhere right now.:( Thank you in adavance for any help!!:cool:

Is it possible your abs module is applying the brakes? Maybe your power booster is applying pressure when it shouldn't be? Do you have access to a vag-com?

Were you braking when the wheels locked up?

Thank you very much Jeff for your help and info first of all! and no the brake lock up seems to happen only after driving for about 20 - 30 minutes. I will say that it has not happened when I have been driving, on both occasions my girl friend was driving it and I was the one who figured out how to free them up. To answer your other questions; the ABS system appears to be working fine (no warning lights) The booster is hard to tell because of that valve it gets vacuum from might be the culprit, and I don't want to start replacing parts until I can narrow it down a bit more.:confused: No I don't have access to a vag-com, is that the 'code reader'? I have heard it mentioned quite a bit here but I never have had any problems with this car. Is that what I need to ultimately diagnose this problem? Anything you can tell me would help tremendously.:confused: Kenny

A person that wants to do any work themselves beyond washing and waxing an Audi needs a VAGCOM. (You can add the guys that want to know if certain wheels look better than others to the W&W group.)

The simplest one is the freebee program and an interface cable for a laptop that usually costs less than $100. It gives you error codes, the ability to reset, and monitor many of the functions. Beware -it is simple , complicated, and fun. The simple part is reading and resetting error codes-- the complicated part is figuring out what they mean -- the fun part is figuring out what the different measuring blocks mean. The internet is very helpful and a Bentley manual is essential --

The bottom line is --IF you really want to be able to "narrow it down a bit more" you need the correct tools.

to echo what NH_USA said.....Yup, the VAG-Com (Vokswagen-Audi Group Communications, I think) is software and an interface cable put out by Ross-Tech for talking to our cars. It's a code-reader that's specific to VW-group cars. They're not completely cheap for the full-up system(2-300 bucks new), but an absloutely valuable tool if you have multiple Audi's or do any of your own wrenching. If you don't have a laptop, you can make do with a desktop and a 100' serial cable extension....(the neighbors had some questions about me after that day).

That being said, you can go to your local AutoZone and they should pull the error codes for you for free. They'll try to sell you other stuff, too, of course. Either post them here or dig though Google to find out what they mean, as they're some cryptic number like "P1932".

As for why.....I'd guess a few things, if I were to guess (again, echoing earlier posters) The ABS controller and/or a wheel sensor is acting up and engaging the ABS system. When this happens, do you hear the growling noise of the ABS pump? You could have some sort of screwball problem with the brake booster itself, which isn't much more than a diaphragm that, along with engine vacuum, acts as a force multiplier. Usually the problem occurrs with the diaphragm tearing, so you loose your power brake, not the other way around. But, well, anything's possible. Has the brake pedal "feel" changed at all from before this started happening until now?

Can you turn the ABS off in a 99 A6?

If the problem returns with the ABS off I'd suspect a sticking check valve of some sort --

Cool idea! Could that be done by pulling the fuse for it, or would that have some nasty downstream concequences that I'm not thinking of? If it weren't the brakes, I'd be all gung-ho on the idea....but being that the only thing more important than going is stopping.... :)

People drove for years without ABS so pulling the fuse or turning the ABS off is not dangerous as long as you know how to modulate the brakes in a pannic stop... Of course brake modulation during a pannic stop is old fat technology --ie before the car was trained to drive it-self...

Wiered Things Going On With Breaks Too, Please Help!
 

ok so I have been reading what everyone has posted on this thread and I think I have gained alittle but still along ways from right so I need some help. First thing going on, I just got my rotors, calipers and breakpads changed. So after that is finish I take it out and when pressing on the break it has like a farting noise which my dad thought it was ABS. So I take out the ABS fuse and it goes away but my car started shifting hard. Next I notice when pressing on the break, there is a clicking noise coming from under my automatic shifter. My car is a 96 A6 Quattro. Please help. Its greatly appreciated.

I hear that! My first car was a 1972 Volvo P1800ES (neat car, too. Wish I still had it. Everyone thought it was a Ferrari Station Wagon!) with a retarded brake booster. Modulation was the name of the game with that puppy.

I just wasn't sure if the ABS fuse controlled anything else that was important, or if the ABS was somehow disabled it didn't allow for the brakes to behave properly. :)

Going back to the issue at hand....have you had any luck, ksmith?