If My ABS module will not communicate ...

[toms73novass]

I have a flashing brake light and ABS / car height light. I tried VCDS and do not get a communication with the ABS Module.

If this happens is it the one in the passenger foot well or the one on the ABS unit?

[seishuku]

ABS module is attached to the ABS pump/valve block in the engine ebay, TCU is under passenger carpet, comfort/central locking is under driver's carpet.

[toms73novass]

My manual said that there was one under the passenger carpet and one on the ABS pump. It says that the ABS/ESP are in those two locations?

[Vinnie981]

You need to replace the Module on the ABS pump. Plain and simple

[toms73novass]

The reason I asked is that I looked at the module master site and they said : "The Bosch Solenoid Pack is part of the Bosch 5.3 ESP (Electronic Stability Program) System. It is bolted directly to the hydraulic control unit, and because it contains only solenoids, seldom ever fails. The solenoid pack is hardwired to the hydraulic pump motor and has a 15-pin connector.
The source of most failures is the control module located behind the glove box"

Here is a picture of the module under the carpet below the glove box.

[toms73novass]

Looking in to it further on searches for the part number 4z7907389 I found several other peoples vagcom printouts and on module 03 ABS it references this number....hmmmm.....

[rollerton]

^ i don't think that's the "ABS" module technically. It's the ESP/ stability module. If that part went bad you'd still be able to comm with the ABS module. ABS module itself is on the ABS pump. I think last time I did one was on a B6 /A4 , mostly identical setup, and I got to it through the fender liner as it's bolted right to the ABS distribution block next to the power steering reservoir. A couple bolts were tricky to get to. You can remove the ABS module (electronic part) itself and the car still drives fine.

[julex]

It is on the pump itself.

It might be wiring still so definitely inspect the connector first before you go about replacing the module in its entirety. And I am not sure that you will be able to replace it "in situ", maybe, maybe not. On my C4, when it went, it was actually a relay tucked in there that crapped out and I was able to fix it with the module in the car. But design changed since then. Be ready to pull the pump and need to disconnect the hydraulic lines with all the bleeding/ESP pump bleeding following this.

[toms73novass]

Ok, Tried again today and bam it connects!!! Was able to clear codes and all seems fine now, WTH? Hopefully it stays that way.

Btw, Took all connections apart all are clean as a whistle...

[toms73novass]

Ok its back, I really think that the controller that the VCDS connects to is J104 which is the one in the foot well. I looked at all the wiring diagrams and they all go to J104, can H and Can L. The only wiring that goes to the ABS hydraulic pump is from J104 and none of it is Can. Can is what is used for the vcds to communicate correct?

Here is the pump diagram only connects to a relay, and motor and J104

[toms73novass]

The other thing I have been finding is ONLY the 5.3 with EPS has this setup, the regular 5.3 and all others have everything on the pump....

[toms73novass]

Here is an example of the B6 that rollerton described as you can see the solenoids are right on J104 on the pump there is no divorced wiring solenoid setup.... At this point I am more posting for others in future searches to find info. I might be wrong at this point, but we will see, I don't think I am.

[julex]

well, have you had any problems with water incursion? b/c that would then make sense that the main ECU would be damaged in that instance.

http://atlanticmotorcar.com/audi-all...module-damage/

[toms73novass]

Last year I did have a damp area under the carpet. I dried it out well and sealed up around the air box. The ABS/EPS back then appeared to be dry. It is odd that it would wait till now to give me issues.

I have taken the cover off the unit and everything looked fine on the side I could see with out cutting the rivets that hold the circuit board down.

Yesterday after it stopped working again and I was not able to connect, I did check all wires/connections for corrosion, none that I could find. I still was not able to connect. After a few more tries, later it connected and I was able to clear the codes. This am all was still fine.

I think I am at the point where I need to purchase one and see.....

[toms73novass]

OK, FOUND THE PROBLEM!! My 16 year old daughter helped me figure it out. Good thing she is not too good with a clutch yet. When she started out she jerked the clutch and the brake beep came on, then went away. That got me thinking, with all the work I did recently pulling the engine and the wiring, maybe I forgot to tighten up something. Yesterday I did check all the connectors in the ebox on the firewall, but I did not check the grounds. I looked up in the wiring diagrams all the grounds for the ABS system. Sure enough, moved the coolant tank out of the way and the ground connection nut was only finger tight. I never tightened it down with the wrench. Wiggled the connection and the brake beep went off. I am positive that was the problem.

Dooh! The simple things...

Now its time to just have fun with the stage 3 car and the stuklr tune!

[rollerton]

Maybe.
Hoping for you that it is, but the 'brake' warning light in the cluster comes on for a variety of reasons; low brake fluid, brake light switch funkyness, low voltage or bad ground? in your case?
Definitely plausible.

[julex]

That would certainly explain capriciousness of the problem.