A6 Avant C7 2014 - Dead instruments, MMI screen and centre console controls

[corkyballs]

Driving along my instruments flickered a couple of times and went off. Having had issues like this in a Vauxhall I stopped the car and restarted it.

Now theres no instruments, the screen for the MMI doesnt flip up, the centre console controls dont work, the parking sensors dont work, the front wipers dont work and some but not all steering wheel controls are dead. The radio is still playing the last station it was tuned to and the system still connects to my phone over bluetooth. The car starts and drives fine.

I've checked all the fuses (divers side, passenger side, rear, steering column and under the ECU), had the dash off and replaced the instrument cluster with a known good one, checked the wiring as best I can for damage but nothing obvious is jumping out at me.

VCDS is throwing hundreds of faults all saying words to the effect of 'inconcievable value' or something like that.

In the fuse panel in the passenger side the lower (black) carrier appears to have two separate power supplies feeding the fuses. The first tests out fine at 12V but the other half (where coincedently) the fuses for the 'Control panel control unit' resides is only measuring at just shy of 1V - is this normal ? I didnt know if this was some kind of CANBUS thing or not as I'm not up on that kind of thing.

My rudimentry fault finding skills are saying 'Is there a relay that feeds this fuse carrier and has it gone down?. The problem is I cant find a wiring diagram or any information relating to what relays do what other than a reference to R2 under the steering wheel being Terminal 15 supply relay which means nothing to me.

Can anyone point me in the right direction please ?

[Elansear]

This may assist, it shows locations of fuses and relays but not wiring diagram. It maybe a hidden fuse/relay that you did not know the location of. Hope this assists it’s about halfway down the page.
electrics Audi A6/S6/Avant quattro (A6Q) 2014 year Audi EUROPA (https://audi.7zap.com/en/rdw/audi+a6+s6+avant+quattro/a6q/2014-717/9/)

[Johnny31]

Have you checked the ones in the boot?

Sent from my KB2003 using Tapatalk

[gav28uk]

I know it's a different car but a 2014 A4 I used to own did exactly that, on the way back from Belgium on a raining Saturday afternoon, car packed with wife and two under 5year children! Nothing worked, not even the windscreen wipers, yet would drive quite happily. I found a local Audi dealership who were open, but the service department were out at lunch and we had a ferry to catch. Anyway, one of the technicians took pity as I had two young kids in the car. They connected it up, loads of errors, no faults or cause and after 30 minutes of trying to work out what had happened quite a huddle of mechanics were trying to help. In the end after making no progress, trying MMI restarts etc, one of the mechanics suggested disconnecting the battery for 10-15 minutes and then reconnecting, effectively doing a ctrl-alt-del to the car. Well they did this and all systems returned to normal as if nothing had happened. This allowed us to get back to the UK, I then booked it into my local dealership who diagnosed some faulting module in/around the steering column, which was causing the total system outage. Unfortunately I don't recall which one.

Good luck with your issue.

[Crasher]

Just doing a Toerag like this, water in the right rear corner got into the radio module behind the side panel and started causing a battery drain and eventually blew the MMI system fuse.

[morski]

Ive got an A5 in at the moment with water in the right cubby area of the boot. Full of water with the loom sat inside it nicely soaked. Audi very wisely (read NOT) make join in the looms with cold weld and then some tape over it. Lots of corrosion on the joints mainly being the heavy duty power and earth connections with the corrosion all the way up its cable. I think i caught it in time as there were no faults apart from the consistent battery drain on a 1 yr old battery. Charge would last 2 days from full charge

[Crasher]

I charged the Toerag up fully yesterday and am leaving it locked up over the weekend to see if it holds charge as it was also only lasting 2 days on a huge brand new Yuasa 9000 series AGM battery.

[morski]

Those monsters have 2 batteries yes?

[Crasher]

That is an option, this just has a big one under the passengers seat, removing it means taking out the seat (two man job) and two men to lift the thing out unless you want a hernia or three like I do...

[corkyballs]

Ive got an A5 in at the moment with water in the right cubby area of the boot. Full of water with the loom sat inside it nicely soaked. Audi very wisely (read NOT) make join in the looms with cold weld and then some tape over it. Lots of corrosion on the joints mainly being the heavy duty power and earth connections with the corrosion all the way up its cable. I think i caught it in time as there were no faults apart from the consistent battery drain on a 1 yr old battery. Charge would last 2 days from full charge

Just thought I'd report back. After hours of fruitless searching I took the car into Just VW in Lincoln, they found pretty much what Morski describes above, water ingress and corroded connections. All connections re-made and the problem is sorted.

Thanks for all the advice people.

[Crasher]

The Touareg turned out to be the radio in the right rear had blown the MMI fuse, our local VW dealer wanted to fit a new MMI unit in the glovebox which was about £6K... I did it with a used radio and codded it in with ODIS for a tiny fraction of that.

Last week we had a 2009 A4 in with almost totally dead electrics, just a faint image on the MMI and a flashing e brake brake light in the dash. I traced it to a large red cable power junction below the right rear light unit (cheap Chinese LED things, all rusty and wet) where water had corroded the battery to car split coupling, tellingly in 2010 the design changed.