JimR

I'm currently getting this fault code, along with the ABS and Check Engine lights, and a nasty beep.

I just looked back into my A6 code history from a couple years ago, and this was the exact same code I was getting when the ABS controller module failed. This is a fairly common thing with Bosch controllers of this era.

The reason I post - while this ABS module failure was common among A4s and A6s, I can't remember very many of them occurring among the D2 crowd.

Has anyone else here had an ABS module failure?

I'm figuring I need to do a couple of wiring continuity checks and reseat the connector at the ABS module, and at the back of the instrument cluster. If that doesn't do it, I'm thinking it's time to try a rebuilt ABS controller module.

PaulW

When I put the S8 instrument cluster in....I was screwing around with it with the cover off....I think I had the connection unplugged on one of the connectors. I would try pulling the cluster and plugging/unplugging.

<img src="http://www.audipages.com/images/tron1.JPG">

treasure

Dear forum friends,

my name is Vassilis, I live in Athens, Greece, and I currently own a 2000 Audi A6 1.8TQ.

I am happy with this car and all it offers, but I currently came towards a very peculiar problem.

During the last 25 days, and after 15-20 minutes of driving, or even without any other particulate pattern, I get this yellow ABS sign and big red exclamation mark (!) on my Audi's board, along with a beep, of course!

The whole pack of trouble signs (i.e. yellow ABS sign, big red exclamation mark and beep) goes away and comes back on its own, without any clear pattern or some kind of logic! The only logical sequence I got to understand was that from a standstill (cold start), Audi's run all diagnostics and give the OK sign. It never starts giving trouble messages right after a cold start. It does though after 15-20 minutes. It has happened that it doesn't give any trouble messages even after 30 minutes of driving after a cold start.

Now,...! What i've done is taking the car to both authorized Audi technician and also to a non-authorised Audi technician (just to have a second opinion). The non-authorised Audi technician, after having a thorough check, told me that the dashboard needed to be changed (that is approx. €900 or $1.338). The authorized Audi technician , after having a thorough check, told me that the main ABS unit needed to be changed (that is approx. €1.300 or $1.933).

I have lost my mind with a) all the money I have to give them (either/or) and b) I am wondering whether this is a common Audi A6 malfunction (I know other Audi A6 owners have the same problem) and maybe there is an official recall process, where I can save some money!

I would appreciate if you could advise me on what do you think could be the problem (just your hard guess, since you cannot check the car). I would also appreciate if you could advise on any ABS recall process that there might be.

Thanks a lot in advance for your assistance.

Best Regards,
Vassilis

tehA8PIMP

Brake pad sensor warning (!!!!! ) or do you have fresh pads?

treasure

I've changed my front and rear brake discs (plus pads) with original ones at local Audi garage, some 5-6 months ago!

Do you believe this might mean something?

treasure

I do not have any pad wear sign!

antiekeradio

Common problem with the Bosch ABS 5.3 module (and also on other types) No recall, its not directly harming safety since the normal brakes still work 100%.

The 'default' error mode of these controllers is 'no communication with controller' usually intermittent.

The cause is a broken wirebond linking voltage supply to the processor print.
These are two parallel 0,3 mm aluminum wires that have been welded on the surface with ultrasonic.

You could send the electrical part of the ABS unit to a company like cheapabs.com who will make new connections to the circuit board with the appropriate specialised equipment. However, since it is only one wire, and shipping costs will be huge if you are outside USA (there's NO cheap repairers in Europe!) you might consider doing it yourself.

DIY repair is possible if:

- you have a VERY steady hand
- you have VERY good eyes
alternative: effective magnification equipment (reading loupe with circular light will do I guess)
- you have a clean, well-lit workspace with no distraction from pets, children, spouses, telephone etc.

Take out the controller as described on various websites that offer repair services. depends a bit on the vehicle how to do it, read up before starting. for Audi's like we have the drill is:

1. Jack left front wheel and take it off -- place jackstand to hold car.
2. Remove fender liner by unscrewing 11 T-25 torx bolts (you will need a set of torx drivers).
3. Unscrew the windshield washer reservoir (2 10mm bolts behind the fender liner and 1 10mm bolt under the hood).
4. Move reservoir to the left to access the ABS unit.
5. Remove the electrical connector on front and back (use flathead to get smaller back connector off)
6. Remove 6 bolts holding on ABS control unit (torx T20)
7. Protect coil side of the ABS unit by placing cardboard over the bottom solenoids

With the controller on the table before you; use a long but thin knife and a hammer to open the cover. Place the knife on the bonded edge. Carefully tap the knife so that the bond comes loose, mil by mil. Or use some other method that avoids flakes getting inside.

You need Silver Epoxy (silverglue, silverpaint, conductive paint) to repair the connection and some chemically neutral glue or resin to stabilise the repaired spot.

Take off the clear coating on the wire as shown in the pictures. DO NOT APPLY ANY FORCE, HEAT OR CHEMICALS on it. SOLDERING WITH A NORMAL IRON WILL KILL THE CONTROLLER!!! the gold pads will come loose!

Do not touch the coating (gel) on other locations than indicated. The gel covers wires that run from processors to substrate (white board) which are almost impossible to see with the naked eye. kill one such wire and you can bin the unit. If some fragments of the cover are stuck to the gel you can/should take them off using a pair of tweezers. grab and lift at the same time, don't press them any deeper into the gel!!!

The trickiest bit is where you need to scratch the surface of the aluminum slightly to ensure good connection with the silver epoxy.
To ensure that the silver epoxy remains 'floating' between the wires you might need to bend them a wheeee bit so that they are closer together.

Dry the silver epoxy with some incandescent lamp nearby; this improves the conductivity. apply a thin layer, dry, then another layer.

Put on the cover with some tape and let it rest for a few hours.

test the controller on the vehicle. Don't forget the 2-wire connector at the bottom as this throws error codes that need to be reset with VAG-COM or dealer.
If the repaired joint is conductive the controller will be alive and communicating with the car. The ABS light should come up at contact and go off after two or three seconds.

When this works we can wrap things up; take it back inside and apply the stabilising glue. Now you can close up the module definately (use whatever works for you, as long as the seal becomes strong, heat resistant and watertight it will be just fine) and let your repair work dry for 24 hours.

Assembly, testdrive to make sure ABS works. If yes; feel like a hero :grinyes:

Disclaimer: When doubting your own capacity to do this repair, you're probably right. Prove me wrong at your own risk!!! :icon16:

When you are reading this your ABS module is probably shot already, so what have you got to loose? I think it is much much much better to give this repair a serious attempt then to stick a piece of tape on the warning light :nono:

In countries / states where ABS is part of the mandatory safety check, it usually is required to have the lamp turn ON at switching on the ignition.

PICTURES

Cover Off:



Gel off, ready to repair. You can see that the shiny reflective line you see on the aluminum has a small interruption on the left, right in the middle of the bend. That's your circuit break!!
Since it's all so delicate I took over twenty minutes to scrape aside all the gel on the connector. It's very soft but not very sticky.



Silver Epoxy to the resque:


(note the wirebonds connecting the white substrate with the processing chips, the microscopic size of it all is just scary)

My method of sealing/closing the cover afterwards (can be reopened) using spring wire.



Thanks to:

- user N3IDT on http://forums.qrz.com/showthread.php?t=171525
- some russian guy running passat-b5.ru; http://passat-b5.ru/remont/abs/
- my dad for making the spring wires and helping with opening the cover, material supply etc.

Greetings from the Netherlands

Wouter


PS if you are concerned about safety; the repair firms do the same work and can guarantee it. These controllers are double-checking every calculation and are specifically designed to fail in a safe manner. If you leave everything else alone, restoring the one connection is enough to regain fully functional ABS. If you do something wrong, like breaking some other connections, the unit will throw an error code and stop working.

antiekeradio

hello Vasilis, I posted an answer to your questions in this thread, but it seems it is stuck in the moderation queue.

perhaps a forum moderator could look into this?

wolfsburgvw

@antiekeradio

Just wanted to thank you for the great reparation procedure. Worked great on my B5 Passat (so far). Will see if it lasts for a while. But so far, no more of this anoying beep!

WolfsburgVW

sarah_pdx

I have a 1999 B5 Audi A4. Had the solid ABS light and blinking "brake" light and intermittent triple beeps. Dealer said the ABS wasn't communicating and quoted $900.

Getting the module off the car wasn't so bad. Opening it up was a bit harder than described above though! Using a "utility knife" I initially tried cutting downward (parallel with the short sides) without luck. I eventually found cutting more parallel with the top worked better (be careful). I also found wedging a paint scraper in behind the utility knife helped the knife to not bind up as much. After cutting the lid off, I had to carefully pick a few lid flakes out of the "goo" with tweezers - as described above.

I looked around and eventually found the exact same two aluminum wires are broken in the exact same place near the gold pads. Actually, I couldn't see it until I (very gently) touched the exposed parts of the aluminum wires with a toothpick. Obviously, I wasn't poking the gold wires with the toothpick - way too fragile.

I'm curious what people are using for silver epoxy. I'm guessing maybe this? http://www.mgchemicals.com/products/8331.html

What are people using as "stabilizing glue" over the silver epoxy once everything is working again? Crazy glue? Another epoxy? Silicone?

What are people using to seal it all up once they're done? Silicone? I imagine heat resistance and a good seal are what are most important.

Thanks!
Sarah