In the old days 95 and earlier audis the electronic unit was under the seat and the hydraulic unit under the hood

now both units are built into one single unit under the hood
still what fails is a solenoid in the unit and stop sending signal to the cluster
the cluster thinks the ABS is not there and triggers the light on
if you manually input 420 ohms in the wire that carries the signal to the cluster the light goes off

 

I have successfully repaired my ABS by changing only the electronic module attached by six torx screws to the hydraulic part. This was much easier than I thought, gaining access from under the left front wing (fender)removing the liner and washer bottle. Also it is then unneccessary to bleed the brakes or disturb the hydraulics in any way.
I also managed to open up the larger cover on the module (behind the solenoids) The trick is to slice it open horizontally with a sharp blade (in the same plane as the cover).
Inside are very complex micro-electronics and I mean MICRO!. However I did locate a tiny wire which had become detached. If I'd been prepared to cut and later rejoin several other tiny wires I could have removed the 12 solenoids for testing.
Nontheless it is possible to check that all the solenoids are correctly attached to their connections by careful examination.

 

A replacement ABS unit arrived from BBA in good order albeit painted the same ghastly all over grey. First I repainted it in satin black and then set about removing the electronic control module ONLY from my car whilst it dried. I then simply swapped the modules over.
After further examination of my own module I attached it to the BBA unit and sprayed it satin black also to send back and avoid a further £70 surcharge.
I have successfully repaired my ABS by changing only the electronic module attached by six torx screws to the hydraulic part. This was much easier than I thought, gaining access from under the left front wing (fender)removing the liner and washer bottle. Also it is then unneccessary to bleed the brakes or disturb the hydraulics in any way.
I also managed to open up the larger cover on the module (behind the solenoids) The trick is to slice it open horizontally with a sharp blade (in the same plane as the cover).
Inside are very complex micro-electronics and I mean MICRO!. However I did locate a tiny wire which had become detached. If I'd been prepared to cut and later rejoin several other tiny wires I could have removed the 12 solenoids for testing.
Nontheless it is possible to check that all the solenoids are correctly attached to their connections by careful examination.
I must stress that electronic repair of the module looks beyond the home mechanic due to it's complexity and microscopic components. However I did find a tiny wire adrift which I reacon with skill I could have soldered. Also if the solenoids themselves are the problem it is just about possible to remove them to test for open/closed circuit. However if a solenoid was found to be faulty where could you get a replacement??? only by stripping down another unit!!!!!!

I have run my car Ok now and tested it on both wet and gravel roads. Vag-com also has found no faults.

 

See my other posts, but ingress of moisture was NOT AN ISSUE with the two modules I stripped. both were well sealed and clean & dry internally.

 

A replacement ABS unit arrived from BBA in good order albeit painted the same ghastly all over grey. First I repainted it in satin black and then set about removing the electronic control module ONLY from my car whilst it dried. I then simply swapped the modules over.
After further examination of my own module I attached it to the BBA unit and sprayed it satin black also to send back and avoid a further £70 surcharge.
I have successfully repaired my ABS by changing only the electronic module attached by six torx screws to the hydraulic part. This was much easier than I thought, gaining access from under the left front wing (fender)removing the liner and washer bottle. Also it is then unneccessary to bleed the brakes or disturb the hydraulics in any way.
I also managed to open up the larger cover on the module (behind the solenoids) The trick is to slice it open horizontally with a sharp blade (in the same plane as the cover).
Inside are very complex micro-electronics and I mean MICRO!. However I did locate a tiny wire which had become detached. If I'd been prepared to cut and later rejoin several other tiny wires I could have removed the 12 solenoids for testing.
Nontheless it is possible to check that all the solenoids are correctly attached to their connections by careful examination.
I must stress that electronic repair of the module looks beyond the home mechanic due to it's complexity and microscopic components. However I did find a tiny wire adrift which I reacon with skill I could have soldered. Also if the solenoids themselves are the problem it is just about possible to remove them to test for open/closed circuit. However if a solenoid was found to be faulty where could you get a replacement??? only by stripping down another unit!!!!!!

I have run my car Ok now and tested it on both wet and gravel roads. Vag-com also has found no faults.

 

Excellent Work!

 

You Are My Hero!

 

I'd like to do the same thing and save a thousand+ dollars in the process! I'm hesitant to buy a junk one for fear of the same failure but if they're cheap enough it's probably worth it. Thanks for the reply....

 

NO, you cannot get the electronics module alone.
I purchased a "remanufactured" EXCHANGE unit complete at approx. half price of new one (with 2 year guarantee - better than a junkyard unit) then split it, rebuilding my faulty unit onto the replacement hyraulics to return.
This saves all the bleeding etc. and is actually quite easy to do.
They are available here (remanufactured) less than half the price of a new one.
http://www.bba-reman.com/index.htm<ul><li><a href="http://www.bba-reman.com/index.htm">http://www.bba-reman.com/index.htm</a</li></ul>

 

It's too big to fit here. I've created a page here:

http://www.nonosi.org/a6absfailure/

Please take a look. I will appreciate any additional information or corrections on this topic.

A6LoverHater@nonosi.org