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Fault Code - 01203 - Electrical Connection between ABS and Instrument Cluster

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Fault Code - 01203 - Electrical Connection between ABS and Instrument Cluster

Old 09-08-2010, 08:55 AM
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it is your abs module at fault, you can send it to modulemaster for a repair that is permanent and under $200 USD.

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Old 02-06-2011, 07:13 PM
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Default Just complted ABS repair

Great thread, thanks for the info. I have the same failure on my 2000 Passat, hte guide was motived me to fix it myself instead of spending a bunch of cash.
I wanted to add my perspective on the problem....
For several years I worked as a process development engineer packaging electronics. Specifically ceramic hybrid circuits, gold wire bonded ASIC. All of this mess encapsulated in silicone.
What are the odds that all of those technologies are in the Bosch ABS unit?
The wire bond that is failing is an aluminum wire bond. It looks like Bosch used large diameter aluminum for the higher current connections, and gold for the rest.
Stress cycles from temperature changes eventually fatigues wires bonds. Aluminum always has a lower life expectance than gold. But it costs less and its processing window is a lot more forgiving.
On any wire bond you have to pay attention to is the shape of the loop. In this case from the bond pad on the ceramic hybrid to the lead frame. The one that fails on our controller comes in at a very steep angle. That angle puts a sharp bend in the wire at the base of the bond on the lead frame. Every thermal cycle the controller sees flexes the aluminum wire at the bend.
Either the original designer did not know that bond pad was going to use aluminum, or he made a major mistake in his design.
The fix:
Because the bond wire is aluminum wire it won't take solder, however the bond pads will. The conductive epoxy is a decent solution, but original problem of an easily fatigued material and a stress point is still there.
I completely removed the aluminum wire bond and replaced it with a pair of fine copper conductors that I soldered to the lead frame and the ceramic hybrid. I'm guessing that the hybrid is metalized with palladium, it solders very well.
Also, as many have already figured out the encapsulation material is silicone. The down side of that is it makes bonding any other materials to surfaces that have been wetted with it very difficult. That's a good reason to consider soldering.
If you're considering re encapsulating the repaired areas I'm pretty sure the silicone is a two part addition cure using a using a platinum catalyst. This is considered a safe material for electronics and is critical to protect wire bonds junctions to the ASIC's on the hybrids. The repaired connection is not as critical .
DOW and GE make encapsulates that are very similar to what was used in the ABS unit.
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Old 11-09-2011, 08:19 PM
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hi there.

so for about 4 days I had a successful repair according to @antiekeradio
's instructions. Until you've been in there, you just don't "get" how small the gold wires really are.

so, on to my issue... lights came back on, abs module is back out now... round 2 of the repair is about to commence.

the question at hand now is "what is this as Stabilizing Glue" mentioned? Who has used what? Crazy Glue?

I haven't cracked the module open yet to see if the repair flaked off, but I do know that I did not do this particular step. so it would lead me to think that this is the problem...

thanks for the time. let me know what you used.

and big THANKS to @antiekeradio for the instructions... once past the size or lack there of of the unit, it's amazingly simple... and broken is broken...not much to lose by trying it!
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Old 10-30-2012, 11:41 PM
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Originally Posted by treasure View Post
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,
Hi Vassilis

Did you manage to solve your problem, as I have exact the same problem with my A6 2,4 V6 from 1998. ?

Kind regards

Stig Bindner - send me an email on [email protected]
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Old 10-31-2012, 12:01 AM
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Default Audi A6 2,4 V6 - 1998

Originally Posted by antiekeradio View Post
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.


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


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.
Hi there

I have exact the same problem with my Audi, but I do not feel up to trying to solve the matter myself. If I dismantle the ABS box, can you then recommend me who could do the repair. ?

Is it OK to drive the car - even it comes up with all these errors, even oil pressure error comes up, or does these errors only come up by mistake. ?

/Stig Bindner - [email protected]
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Old 10-31-2012, 03:49 AM
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Here >>>


If they don't do international, I'm sure there's a Euro counterpart...just Google "ABS Module repair".
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Old 01-13-2013, 06:52 PM
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antiekeradio, many thanks to you for the write up and pictures of your silver epoxy fix.

I have some moderate soldering experience, a couple HeathKit projects and some cold solder/broken circuit board fixes, but when I cracked open the 5.3 ABS module and saw how tiny those wires are, I nearly gave up.

However, the damn thing isn't working anyway, so what the hell? I bought an $8 head band with lighted magnifier, and the 8331 conductive epoxy on Amazon. I used two halogen night stand lamps pointing at the work. Sure enough, the two aluminum wires had separated from the gold pad.

I used a couple plain old tooth picks to scrape off the majority of the gel from the pad and the aluminum wires. Then I used some very tiny cotton swabs with MEK to clean off the rest of the gel residue. Then I lightly scraped both the pad and wires with a small x-acto knife. I mixed the epoxy with a tooth pick, and applied it with the same pick. I had originally intended to do two coats, but the first one ended up so thick, I didn't think there was any point in a second one. For the same reason I did not use any stabilizing glue.

I let it dry under the hot lamps for a couple hours, and then for another 24 hours. I ran a bead of automotive RTV around the edge of the box, and then clamped it shut. I then mixed a batch of JB-Weld and ran a bead around the outside of the seam to hold it shut permanently.

Going on two weeks running now, and the fix is working great! No more ABS lights on the dash. I would have posted pictures, but mine were not as good as antiekeradio's.

For those of you considering this fix, pay the very closest attention at ALL times to where the end of your tool is under the magnifier! I nearly knocked off a couple of those tiny gold wires thru loss off attention for just a millisecond! But it is doable!
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Old 01-17-2013, 01:15 PM
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Default See this video

Ok see how I fixed my ABS for $1 BUT worse case you'll have to send it off to Florida and get it fixed for $99 tops.

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Old 04-27-2019, 10:17 AM
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Default I happen to have the same problem I replaced the abs module n now I can't program

I have the same problem I replace the ABS module and now I took it to get program another saying that has an electrical problem it can't connect to the scanner for some reason ..would you know what could I do about that
I was thinking of disconnecting the whole computer and see if that might do something

Originally Posted by JimR View Post
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.
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