I've recently purchased a 2000 A6 wagon with about 130k miles. It had the ABS/Brake light showing and gave the 3 beeps at startup. Doing some google searching, I found that many folks experienced this issue and really, it should have been a recall from what I've read and observed in my case. My son urged me to post how I was able to repair this issue in the hopes that someone else may find my experience helpful. Unless you plan to attempt this repair, what follows is long and not a good read, but it might help the few that want to try this at home.

The heart of the problem is the Bosch ABS module that is mounted near the washer fluid bottle on my Audi. The model number is 0 273 004 284, or -283 and maybe others, but mine ended in 284. There is a wire connection internal on the module that breaks, fully or intermittently causing the ABS system to fail. The code when read shows as a communications error, but you know because of the light and beeping.
A quick search will turn up many sites that offer to repair your module for you from prices anywhere from $60 up thru $600 for a rebuilt exchange. There are a few videos on youtube demonstrating folks making the repair, but from what I could read in forums, everyone that tried the repair at home ended up worse off than before the effort. There is one video that shows a company using million dollar machines to rebuild the modules with tech that one could only dream about using at home.
I think there are a couple reasons that folks come up short trying to fix these at home. If you have no experience at soldering, then you need to find someone that does. Really, you need to find someone that is very comfortable using a soldering iron and owns a good one. Lots of posts mentioned going to the store to purchase an iron, then having a go at the module--not going to work. These are very tiny connection points, and they are nestled in amoung dozens of other points you don't want to disturb. A needle iron is required, one with a tip that really is as narrow as a needle--you don't get them at Lowes.
The other issue is the goo thats covering all the existing wire connections. You can't see the wires because they are about a tenth the diameter of a hair, but each land or connection pad in the module has two or more of these tiny wires connected to them. The wires are attached not by solder but by ultrasonic welds. Folks tend to want to clean off that goo so they can get at the wire to replace, but moving the goo around breaks the tiny wires off. Instead, use a toothpick or small probe and only push aside the goo that's covering the two spots you need to solder. There are two aluminum wires that run from the board to the connection strip on the edge of the box. Look at the youtube videos to see these, but there is only one set of large (by comparison) double silver wires. Using a probe tip, tug on the wires and you see that both are sheared off at the bend made near the edge of the module case. I believe the tool that installed these wires nicked them and that's why they shear off in time. You need to replace these with one good copper wire. You can simply tug the original wire off the land to remove it. Use the needle iron to tin both spots where the replacement wire will go, scrape the land a bit with the needle tip to help the solder adhere. You should be using real multicore lead solder, not that non-lead crap.
I used a strand from a multi strand wire and tinned it first. Using the needle iron, get one side in place and nip it to length, then tack down the other end. Leave the goo alone as much as possible. Once complete, I plugged in the module prior to closing it back up to check that it was working. Use a bit of rtv to reseal the box over the module.

Sorry this is such a long post, I hope it helps folks decide how to fix their ABS module.

 

I had tried repair using silver conductive epoxy, but it didn't hold. Went Module Master approach afterwards. You are certainly right that soldering with needle iron is necessary. Good lighted magnification & a delicate touch is also necessary because of the tiny tiny wires. Here's pic I took of the 2 Aluminum wires you mentioned . This is after I did the silver epoxy un-fix. The shimmery surface away from the Al wires is the slimmy insulation goo you mentioned. Again a delicate touch needed to move this away. I bumped one gold wire on the left & it broke off the tab, so had to un-fix that too. To put size into perspective, a toothpick tip is amost the width of the smaller gold tabs to either side of the center tab that the silver wires attach to. FYI, this is for a Bosch 5.3 ABS Module. This repair is certainly not an easy DIY. As Twainer mentioned you need proper soldering tools, along with the light touch soldering skills, good lighted magnification, & assorted tiny tools to remove the goo & hold the wires.

 

Hey guys, thanks for this great info. One question, will I be able to drive my car temporarily without the module?

 

Sure. For the most part the module is a separate unit and nothing is left hanging while its off-board.

 

yes you can drive the car with the broken ABS & with the module removed (in case you wanted to send it out for repair). However, if you plan on driving w/o module, you should wrap the harness connector in plastic bag or some water proof wrap. Also, I suggest covering the module mount location with foil or plastic wrap to keep it clean also.
Unfortunately for us, after the ABS module got repaired we now have a short in the wiring between the module & the instrumentation cluster. Haven't figured out exactly where yet, so although we have a rebuilt ABS, the short keeps it from working.
For now, the ABS module is not installed, & my son's been driving it that way.

 

Had the same problem of solid yellow ABS light and flashing brake light with three beeps. On reading this forum found out that its a faulty ABS ECU. Took it out and sent it to Cheap-ABS for repair. (Costed me only 110$ for the repair plus return shipping) and has been working fine. If you are looking for a video on how to remove it Cheap ABS has excellent tutorials on removing the ABS

 

Crubby -how do you know it's a short between the abs and instrument cluster and not a bad abs module repair? How do you tell the difference? Is the warning light different? I'm wondering if my abs light in my 2000 A6 is due to the module or a wiring connection. Just bought the car.

 

On Youtube I saw the person sawing the abs module from top to bottom. The module on my '00 Audi A6 looks like you can cut in from the side where the glue is -I'm wondering if my module has been redone before or do they all look like this? I never took a good look at my last Audi module. I'm trying to decide whether to buy a used one or have mine rebuilt. Some companies don't rebuild ones that have already been rebuilt? You can kind of see the clear glue they used in the pic on the top right if you look close (light reflected off it). Thanks if anyone can help.
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2000 Audi A6 Quattro

 

For 1st problem with ABS, VAGCOM check showed it could not communicate with ABS module. This was due to the broken silver wires.
After getting repaired module from MM, VAGCOM check now shows:

01203 - Electrical Connection between ABS and Instrument Cluster
31-00 - Open or Short to Ground

I even have a 2nd repaired ABS module & get the same 01203 code with it. I've checked wiring between Module & cluster but cannot find any open or short to ground. I've checked from the connector to the ABS module to the connectors on back of cluster, & all tests good. I'm stumped. Could it the open/short be within the cluster? If so how to test that?

 

After looking around, on YouTube there's a person that received this code w/a bad module-Title is "Bosch ABS defect". Maybe the repair didn't hold? Check ABS coding is another possibility-of course I'd try first