1999 A4 Avant Quattro 1.8T:
Last 3 weeks the ABS light will come on briefly, accompanied by its 3 beeps, followed by the BRAKE warning light, then it all goes off. On a FEW occasions they've stayed on as long as 5-10 minutes.

Audi tech said only problem with continuing to drive under those circumstances are: (1) ABS may be out, and (2) brake lights may not be working.

Brake lights ARE working, I found out, but I haven't had any opportunity to test the ABS while the warning lights are on.

Tech and I feel we need to wait till it all stays on, so that it can be diagnosed more easily.

Any experience with this? Any hints? What could be starting to fail?

Paul

 

The abs brake control modual, it can be rebuilt from modualar masters for $250.

 

Some newb posted this under a glowplug concern, but im pretty sure it was supposed to go here. Its a posiblilty but usually bad brake light switchs throw a fault. Considering the price it may not be a bad idea to try a brake light switch, but im with tractioncontrolon this. You probably need a new module. Its been documented on here many time.

 

Have you tried removing all the ABS sensors and checking that they are not built up with metal shavings. This will cause the computer to give a false alarm.

Very easy to do. They just pull off... Just need to remove each wheel.... If there is one/two with a considerable amount of build up clean them (they are just magnets and just need to be pulled off) then keep driving and see if the alarm comes back.

 

nzant is right, I had the same issue and it was caused by bad abs sensors ... you should get the code from a vagcom, it's gonna tell you on what wheel the issue is from, that's what I did ... and by the way, even with those alarm on, that didn't stop my abs from working ... at least on the wheels with good sensor ...

 

Even with the vagcom it will not necessarily tell you which wheel, just which side. Mine had the front right sensor cable worn through and the vagcom spat out codes for both front and rear right. I suspect that they must be joined in a series (not that i know what i am talking about as i hate electrical)??

Hope this is will resolve your problem. Otherwise i would check that it is the connection to the abs module (apparently a common problem) which may just need to unplugged and plugged back due to a bad connection, or faulty sensor/s.