danielb3

Hi I'v got a 2004 A8 with some strange electrical problems. The car has been pretty much stood for about a year while it had paintwork and a few other bits done but now it has developed issues with its electronics.

1. The boot will not close and the release motor is getting very hot
2. The 3rd brakelight is on when ever the ignition is switched on
3. The nearside rear light is on permanatly even when the car is locked
4. None of the rear lights work
5. The MMI unit was always tempramental, it would work for 30 minutes then shut down but now nothing the screen wont even open
6. It can drain a full battery in around half an hour

Any help would be greatly appreciated.
Thanks,
Danielb3

Edd W

That sounds to me like it was jump started directly onto the battery rather than using the correct terminals located near the battery. This could have damaged the power control module.

Is that likely to have happened?

If it is draining a good battery in half an hour, firstly there is severe fire risk but secondly, the main place that the power is draining should be obvious - something will be getting very hot.

mishar

You need VCDS scan. It looks like some wires where connected where they should not be. Could it be related to that paint job?

By the way, jump start should be directly to the battery. Charging to the shiny hex post.

05SilverA8

I had some work done in the rear (dealer ended up scratching chrome piece in back). They had to remove driver rear lights. When the car was returned, they had broken fiber optic cable replacing lights. This caused MMI to not function. My guess is they messed up something when they put it back together. VCDS scan should show all kinds of errors in this area.

danielb3

Hi thanks for all your replies, a bit more info. I've been told that when it went for paint the only electrical fault that it had was a faulty window switch for the nearside rear window.

The battery was flat and it was jump started using a Snapon battery booster. It did damage the engine ECU which has already been replaced by an automotive electrician. It also went to them with no electric windows or central locking. It came back with the engine ECU replaced and it running fine. They also diagnosed it with "a dead module in the boot". I fixed the electric windows and the central locking by just plugging in the drivers door module , but there are no rear lights and the MMI screen still doesn't open.
Thanks again,
Danielb3

Edd W

I stand corrected.

So as far as the car electrics are concerned, a jump onto a flat battery is seen simply as it having a good battery, but charging from a separate charger is seen as if the alternator is on overtime and has to be done through the power management module?

mishar

It looks like they have burned more than just ECU. That "booster" is more like killer, pumping high voltage. Quite higher than 14 V the system is designed for. You still need VCDS scan. Lights are controlled by Electrical Module and MMI screen by MMI Head Module. Could be quite a few bucks.

s4master1

sounds to me you have a bad brake light switch and a bad battery to start.

MP4.2+6.0

Short version is look for a poor connector attachment back by the battery and a possible now damaged trunk motor. But I'm unsure when you say rear lights if you mean the rear seat ones (inside), or the exterior tail lights. In any case, more background and possible pointers below:

By chance some of what you are describing sounds similar to another poster's experience ("Vici") when he just recently did quasi factory rewiring connected to a trailer hitch install. Similarly he was working in the rear battery area [your further reply mentions a battery jump w/ a heavy duty type unit], even though for other reasons. Along the way, pulling a key connector back there without the battery disconnected took out his rear trunk latch motor, and the connector being loose affected his (car) tail lights.

See this post: https://www.audiworld.com/forums/sho...php?p=24455505 It's kind of buried, but deep in that post read what is in step "3" toward the bottom and you will get some sense I think.

and also this post: https://www.audiworld.com/forums/sho...php?p=24454600, which also goes w/ this post: https://www.audiworld.com/forums/sho....php?t=2848794. It got worse in this sub part of the same thread where the tail light issue surfaces more prominently and the trunk motor damage become apparent: https://www.audiworld.com/forums/sho...php?p=24453078

There are other replies and parts to the thread, but those handful will give you some sense and how it may overlap with some of your issues.

danielb3

Hi, sorry I've not updated for a while I've had a lot of work on. Thanks for everyone's replies, I already have Vagcom and a KKL lead so I plugged it in on Friday and ran an engine scan which resulted with 10 errors (attached as Firstscan). I deleted them and then ran a full auto scan which only returned one error (attached as Autoscan). I'll check all the connectors around the battery when I get chance to. One thing I did notice is that the rear bumper has been smoothed and the parking sensors unplugged.
Thanks again,
Danielb3