my ABS light has been on ever since i got the rear wheel bearing fixed, and not just recently the brake light "sometimes" comes on flashing and beeping at me unlike the ABS light which stays solid and doesnt beep.

i know for a fact that my ABS doesnt work because i slammed on the brakes and the back ones locked up

 

I know the module / pump unit is a common failure point. I bought a used one on Ebay in anticipation of replacing it when I had the MILs. But ... before I swapped it I got my car scanned by a dude named Matt that I found on the VAG-COM list. He scanned my car. Came up d/s rear speed sensor. I replaced it for 40- (used). Installed it and the ABS works (didn't before) and the ABS/BRAKE lights went off immediately. Without getting your ABS system codes read you are taking a shot in the dark with what will fix it.
As a side note: If you don't have access to VAG ... the bad wheel speed sensor on my 98 a4qm30v gave no ohm reading at all. The good one gave a value when I put the electrical tester probes (like 3 or 4 ohms) on the leads. If you had a wheel bearing replaced I would check the connections and put the tester on it and perhaps the one opposite it to compare.
Good luck!!!
My brother (e39 bmw) had his module sent out and repaired for like 150- and he swears by it. Probably better than a used one with unknown history and miles.

 

I've got the same thing and the VAG cannot even find the ABS module - just polls the address for it and fails. In my research, I read somewhere (that I can no longer find) that in some cases, problems with our ABS module can cause incorrect brake bias causing you to use mostly your rear brakes in normal braking. I think I may be experiencing this as I seem to have less braking power and it does feel like I may be using much more of the rear brakes when I stop. Is this possible that this is the case?

 

Alright, since there are so many people here with the same problem, everyone in this thread who wants their ABS module repaired, send me an email or PM. I normally do it for $110 on ebay, but I'll do it for $80 for anyone who references this thread.

sidespar at yahoo dot com

 

Just to close my issue here - I got my ABS module repaired from www.modulemaster.com. The ABS module works great now. They gave me a warranty on the repair (5 year? Lifetime? Can't recall) and charged about $200. I know sidespar charges less, but since this place has a GREAT website that helped truly diagnose my issue and lots of great feedback from years of customers, I felt they should earn my business.

 

Prior to arbitrarily replacing your ABS module, get it scanned with a vag-com. You can buy one or find someone that has one.

Buy - http://www.ross-tech.com/products.html
Locator - http://www.vagtoolfinder.com/locator.aspx