Audi A8: Driver Side Control Units Malfunction

Hello everyone,

I recently purchased a used Audi A8 D3 (model year 2007) for my personal use. The engine code is BVJ.

Impulse purchase, unfortunately didn't have a VCDS with me. Reported defect: The side windows on the driver's side (front and rear) are not working.

Read from home directory, see log file.

"In practice, the following features are currently malfunctioning on the driver's side: the front and rear window controls don't work, the power closing assist for the front and rear windows doesn't function, the buttons to close the windows located on the door handles of the front doors don't work, and while the keyless entry works in the back, I have to pull the handle completely up in the front for the central locking to open (normally, you only need to put your fingers under the handle). Everything functions as expected on the passenger side."

"During the first rain, the C-pillar on the driver's side started filling with water because the drain from the sunroof was blocked. A large amount of water leaked out and flowed into the footwell on the driver's side. Now I suspect water damage (which probably happened to the previous owner as well)."

What could be broken that is preventing all these control units from receiving power? I can't believe that all of these ECUs are faulty.
Moving assistance.
Door, front, building section j386.
Rear door seal.

The switches are functioning according to the actuator diagnostics. All fuses have been checked.

Does anyone have any ideas, experiences, or tips on how to proceed?

Best regards.
Adrian.

The errors often occurred in groups. It's possible that there are some loose connections causing the problem. However, it could also be a result of previous troubleshooting attempts.

Therefore, I will first save the error memory logs. Then, I will clear everything and see what errors reappear in which groupings. Only after that would I begin searching for solutions, because it's not yet clear whether some of the errors were caused by the previous owner or their workshop.

Greetings.
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

Thank you for your reply. I had already cleared the error memory a few days prior, and then created this log after a longer drive.

Quote:

A large amount of water came gushing out and flowed into the footwell on the driver's side, at the rear.

Are the wiring harnesses in the vehicle floor, under the carpet, not deteriorating?

Best regards, Rainer.

"I haven't removed any carpets yet because I'm not sure if the relevant cables are actually located there. I'm still hoping someone can tell me that this is a typical issue with control unit XY... before I have to disassemble half of the interior."

Die ganzen Fehler sehen sehr nach Gammel in Kabelbäumen und Steckern aus. Apart from that...

Quote:

11.7V/11.7V. VIgn 11.6V

If the onboard voltage is too low and fluctuates significantly (e.g., 11.5V in one case, 13.2V in another), this can also cause malfunctions and error messages. Is the battery okay? The battery management system is reporting excessively high quiescent currents. I would start by investigating whether the battery is okay, then check the fuse box, and finally examine the wiring.

Best regards, Rainer.

I also suspected the battery: The first time I programmed the pre-heating system in the morning, it was off when I got to the car. There was a stored error message about "emergency shutdown due to battery voltage" or something similar, which I unfortunately didn't save. That day, as usual, I drove about 4km, and the next day the pre-heating system worked for about 15 minutes. The following days were also like that, and it always worked. However, the battery is from 2010, so I probably need to replace it anyway.
But does insufficient voltage cause all those failed components to fail at once?

beathooven wrote:

I had already cleared the error memory a few days prior, and then created this log after a longer drive.

The errors occurred over a period of approximately 14 days. I checked the logs from October 23rd to November 8th. Are you sure that you cleared all error memories, or just the one in a specific control unit (STG)?
Did you immediately perform another automatic scan after deleting the error codes to see which errors reappear with just the ignition on?

PS: The A8 D2 had two batteries. Also, the Phaeton 3D also has two batteries. Does the A8 D3 really only have one?

Greetings.
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

In the D2 model, the second battery was removed starting with the facelift; after that, there was only one battery available, regardless of whether it included a pre-installed heater. In the D3 model, there was only one battery from the beginning.

I would also check under the carpet; the 4B often has a typical wet spot there where there are problems with the wiring.

The keyless entry system is a common issue with the D3; the door handles often break, and it doesn't necessarily have to be related to water damage, although that's certainly a possibility.

Wow, this forum... Why was I so hesitant for so long to buy VCDS...?

Let's go back to the battery. When fully charged in a resting state with a charger connected, it reads 12.2V. When the ignition is turned on, it drops to 12.0V, and when the auxiliary heater is turned on, it drops to 11.7V.
It's probably damaged... a new, genuine Audi part will be available next week.

"Turbinchen, thank you very much! So, the issue with the keyless system seems to be something I can disregard for now. And the experience that things tend to go wrong there motivates me to address it as soon as possible!"


Dear Guste, I'm really embarrassed about this... But you're right, the errors weren't actually cleared! I've now read and deleted the error codes about 10 times using VCDS, and immediately performed a new scan afterwards, but the same errors keep reappearing with the same date! I started to doubt myself and watched a YouTube tutorial, and I'm doing everything exactly as explained... And it's happening exactly like in the video. Has anyone else experienced something like this?

I've now deleted the errors using a different adapter. Here is the new log.

Hi.

Quote:

I read and cleared the error codes 10 times using VCDS, and immediately performed a new scan afterward, but the same error codes keep reappearing with the same date!

I started to doubt myself and watched a YouTube tutorial, and I'm doing everything exactly as explained in the video... And the exact same thing happens as shown in the video.} Has anyone else experienced something like this?}
No, did you use the broadcast message via CAN or did you clear it individually in each control unit?

The simplest and fastest solution for all cars with CAN-based diagnostics is to send a "clear all faults" command.

Regarding the auto-scan: It looks much better now! Let's see about the power window issue. It might be due to corrosion or moisture in the door, which could also explain the problem with the window lifters. I'll wait to check the ESP system until the new battery is installed, because when the ESP activates, it requires a lot of power, and a weak battery can cause the on-board voltage to drop.

Best regards, Rainer.

Hello, and I'm sorry for not getting back to you sooner. Unfortunately, I haven't found the time.

I chose the option "delete all errors" in each case.

Ich habe nun gestern eine neue Batterie verbaut & neu codiert. Danach alle Fehler gelöscht und vorhin neu ausgelesen. Here is the log.

It's strange that the errors related to door electrics have older timestamps associated with them. Is there an explanation for this?

Just now, while doing some diagnostics, I tested something I always forget to check: opening and closing the windows with the central locking remote. Nothing happens at all, on any of the windows. I'm increasingly suspecting a problem with the comfort system, but could it be defective to such an extent that only one side of the vehicle is affected? And without leaving any error codes...

Next week, I'm allowed to go into my father's private garage to take a look at something. I'll be removing the carpet, door panels, etc.

I am checking:
- Cable breaks, door guide.
- Exposed cables/plugs near the door and under the carpet.
- Comfort control unit (how to test it, I still need to figure out...).
... any other tips?

Hi there,

Hopefully, the new errors in systems 01 and 03 are still due to a calibration run that hasn't been performed yet after the battery replacement?

Driving a short distance and turning the steering wheel fully to the left or right once should make them disappear.

Since the heating element in the footwell area is also not working, I cannot believe that the problem lies with the comfort control unit.

I would remove the driver's seat and the right rear seat, take off the trim pieces at the entrance, and pull back the carpet to the center console. Then, I would carefully inspect the cable distribution blocks that are integrated into the wiring harness. I suspect that at least one of them is corroded and needs replacement.

To clear error codes: After clearing the codes, check to ensure that no new ones are reported. If there are, then go to the control unit and clear the error memory there. Perhaps the overall system message isn't working for some reason.

PS: What about the multimedia stuff? Is it expanded but not decoded, or are the error messages genuine?

Greetings.
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."

Yes, I didn't know about the calibration. Thank you for the tip. I have now done it, but the error with the brake remains .


"You're right, Guste, there probably isn't any connection to the 'Komf.stg.'"

Getting rid of the seat and carpet is proving difficult. The A8 doesn't fit into any standard garage, and I don't have anything larger available where it could be stored.

Thema Fehlerlöschen: Rundmessage geht nicht bei diesem WAgen. 100x probiert ohne Erfolg. Jedes Stg. einzeln funktioniert dann einwandfrei. Whatever...

Multimedia system: It has the original AMI 2g high unit with a 6-disc CD changer installed. No additional AMI adapter is needed. Everything seems to be working fine so far. You're asking about the "MediaPlayer 2 not accessible" message? I had overlooked that because everything else was functioning.

Attached is the latest log file again...

beathooven wrote:

There is the original AMI 2g high system installed with a 6-disc CD changer. It's not an AMI adapter. Everything seems to be working fine so far. You are asking about the message "Media Player 2 not reachable"? I had overlooked it because everything was functioning.

Yes, I'm trying to identify the common point for all the errors.

The multimedia system might be incorrectly configured: Media 1 is reporting as active but isn't registered, while Media 2 isn't reporting but is registered. As a test, try unregistering all media in Gateway 19 and then registering only Media 1.

Otherwise, I see errors in...
1) Front door, issues with power supply and closing mechanism.
2) Door HL, issues with power supply and closing mechanism.
3) Foot heating (HL - seems to be working again according to the last log, or hasn't been mentioned since it was reset).
4) Voice control is not responding.
5) Door HR, button defective.

Did you get a wiring diagram for your car from Erwin? Then check which small fuse controls the left door and the heater. After that, please see which large fuse these smaller fuses are connected to.

1) Front door, SB39.
Door HL, SB41.
3) The heating element HL is connected to SB33.
"This is a very tightly packed area in the fuse box. Could you measure the voltage there? However, it could also be the ground point (either near the left A-pillar or under the driver's seat) that has corrosion."

I'm not sure how the voice control module (located in the trunk) fits into the error pattern, but it might be unrelated.

Greetings.
Sure.

Here is the translation of the text from German to English:

"Guste" means "gust" in English. It can also be used as a verb, meaning "to gust."