pr0xZen

TL;DR
'm a bit over my head with ElsaWin flow diagrams. Rear hatch (Avant) and driver door intermittently, randomly, register as open (with cluster illustration + interior lighting). Can "stick" from minutes to days at a time. No Codes. Alarm won't arm, interior lights stay on (Bc it thinks doors are open). - - ABS error (And dash warning) 01203 - subcode 03-10 No signal (between abs and cluster), also intermittent, comes and goes like "the doors", ABS operates fine.
Suspect bad or corroded wiring, ground, connector etc. Need help with ElwaWin flow diagrams to find common points, a bit over my head reading them properly.
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My '99 euro A6 C5 Avant started acting up at times this summer, and has progressively gotten worse over the autumn and now early frost. It started out with rear "door" (Avant hatch) sensor randomly registering the hatch as open. At least I think its the sensor - the rear cupe roof light would stay on, the electronic lock wouldn't cycle and the "car siluette" in the cluster would indicate that the hatch was open. When closing it. This is an intermittent problem, ie. some times it works as it should, some times it doesn't. I can be driving down the road then suddenly the rear roof light goes out, the "car siluette" in the dash showing the rear hatch as open, disappears. If I go to open the hatch, The lock cycles open so I know it finally sensed the hatch as closed and cycled the lock closed. Then anywhere from 5 minutes to 2 days later it would act up like this again. And as long as it doesn't register the rear hatch as closed, the alarm won't arm either.
ow a month or so later, the driver door starts doing the very same thing. They're not fully linked, the rear hatch acts up more often than the driver door, up to now anyways. The front cupe roof light comes on, the door courtesy light comes on, and the "car siluette" in the cluster illustrates the driver door (or both that and the rear hatch) as being open. This too, comes and goes, but at this point its there more often than not, and I have to turn both cupe lights "permanently" off to not drain battery when parked (this is an issue whith 5-6 hours daylight at best, for the next 4-5 months. A VCDS scan reveals no codes related to doors, locks or alarm. Guess the circuitry here is of the simpler sort? It just thinks the doors are legitimately open, which I guess is not inherently an error in principle.

Last month or to, ABS also started acting up, this also intermittently. Get the big red blinking exclamation point and 3 warning beeps. This I can't just "swipe away" from the cluster display with the stalk button of course, as you can with some other warnings. ABS function seems unaffected, and this also comes and goes at random. This does, however, leave behind a DTC on the ABS unit (module 03- mine is a ABS/EDS 5.3 QUATTRO D00) That code is: 01203 - Electrical Connection between ABS and Instrument Cluster - Subcode 03-10 - No Signal - Intermittent .

The intermittent nature of these and their arrival fairly close together, has me suspecting they are related. A friend sent me some ElsaWin PDF printouts of some flow diagrams, so I could try to look for common connection points for these 3 things - a common ground point/connection, a common connection block, maybe a common connector to the cluster (Cluster is an C5-KOMBIINSTR. VDO D10) ? I really need to try to narrow down the search scope before commencing further, as weather here is freezing and horrid the next 5 months and I don't have an indoor or well-lit place to work the car. Nor can I afford just throwing locks, switches and clusters at it just to see what happens.

I'm a bit over my heat with these flow diagrams. Could anyone with ElsaWin and maybe a bit more competent at reading these, see if these things have any common grounds, live feeds, connectors etc?

Harleyguy

Suspect broken wires for both of these issues. The wiring from the car chassis to the hatch flexes when the hatch opens and closes. After doing that a few thousand times the wires often break at the flex point. The ABS may be due to broken or disconnected sensor wires at one of of the wheels, especially since the warning appears spontaneously ( like after hitting a bump, rough pavement, pothole, etc.) Having said that, the scan says it is a wiring fault between ABS and instrument cluster. I would hazard a guess that it would be in the engine compartment near the ABS unit or where the wiring enters the firewall.

georgeb944

I have attached a pdf document that has helped me numerous times when trying to figure out wiring diagrams.

For the most part, ground is at the bottom of the page. Unfortunately, with the Comfort Control Module, the grounds and the circuits are extremely convoluted.

It sounds to me like you have an intermittent switch in the rear hatch, possibly one in the driver door. They are microswitches and have a high failure rate. It is generally easier to replace the entire latch assembly.

The ABS problem wounds like a wire in the process of breaking. Give it time, it soon will become a solid failure.

pr0xZen

Thanks for the PDF, I'll have a read. As for the flow diagrams, I only have a few pages available so I can't really trace all the circuits all the way.

So did any of you check the flow diagrams? No common ground or live points, or connectors, for any of the 3 circuits?

Harleyguy

I did not look at the flow diagrams. I think you have two separate issues that have occurred at nearly the same time, purely by coincidence. The car is approaching 20 years old and even if well maintained, issues will happen. George is usually spot on in his assessments. If you don't find any compromised wiring or connectors, consider replacement of the micro switch for the hatch open warning issue.

pr0xZen

Oh I am most definitely familiar with issues arrising "merely" from old age, that has been the story of this one as long as I've owned it. Most of these I've been able to eventually trace down and get sorted, but earlier I had help with flow diagrams, which is no longer available. I do not doubt George's assessments, I'm just asking if someone well versed in ElsaWin flow diagrams, would be kind enough to sacrifice a few minutes to take a look, so that I might be spared spending hours pulling out unneccesary heaps of covers, trims and parts out of the car outside in these snowstorms, randomly testing wires trying to trace the circuits. If I indeed don't find compromised connectors or wiring, parts come next, but I need check that wiring and those connectors first. And humbly need a bit of help locating them. Because throwing parts at it to see if anything sticks, is my last option. I can no longer afford stocking up more brand new spares for parts that turned out to be perfectly fine - local part sources don't do returns after (test)fittings.

georgeb944

Attached are the 22 pages of the central locking wiring diagrams.

Good luck.

georgeb944

Attached are the 6 pages of the ABS wiring diagrams.

Good luck.