Complete electrical failure

[PAUL MCFARLAND]

Please bear with me on this on.

A4 Avant 2011 B8

4 weeks ago heavy rain 60 mph complete electrical failure, restored a few seconds later. several seconds later same thing. No electrics at all, no lights on the dash, car didnt stop or stall. stopped took 5/6 attempts to get the fob out and stop the car. Put fob back in and all was normal. drove for a while no issues. same thing happened briefly the following day and no issues since. This week got a battery light in and 'Alternator Failure battery not charging' Stopped the car restarted and after a few seconds the same problem. Drove to my usual mechanic (he is an ex audi guy) he says the battery isn't charging so assumed the alternator was at fault. New alternator fitted and the same problem is there. He has tried various components and nothing even got a new loom that runs between the alternator and the starter and same fault. anyone have any ideas. Nothing on the diagnostics??

 

[MuPPeT_ON_TouR]

Hmm.. long shot. Just read somewhere about water getting into a computer box thing with relays in under the front skuttle panel someplace by the windscreen wipers that due to a blocked drain fills with water and throws all sorts of electrical faults.

I might have dreamt it, might not even be for your car.

I am sorry if this turns out to be a bum steer.

 

[MuPPeT_ON_TouR]

https://www.audi-sport.net/xf/threads/bulkhead-and-ecu-relay-box-full-of-water.313965/

 

[PenttisHSR]

There was also this post from Dr dre bw.............

The problem is a mistake made by audi...near the cimputer box which is under the right wiper there is a drain for rain water or water from carwash...apparently the drain is so near the computer box to the point that when there is too much water like during heavy rains or if the drain is partially blocked by accumulatio of grass or dirty then WATER WILL DEFINATELY ENTER THE COMPUTER BOX.the problem is that water can easily get in..but not easily out..so it will accumulate..this causes short circuit in two relays labbelled 643 in there...and these relays are apparently responsible for esp..parking brake and gearbox transmission...so the intermittent problems with be parking brake failure light.sometimes the rear camera engages while driving because the car thinks u are reversing...and the headlight control range malfunction...and when the problem is prolonged the wires which are connected to these relays ..joined together by compression and insulated will corrode...then the ac fan will start even when the car is off and sometimes the xar will just stall when driving..which happened to me several times in highways at night..which is very dangerous...so fix is open the computer box ..it has got 3 torque screws...remove the mother board by releasing two locks on each side by fingera..then remove the fusebox by unscrewing the earth connection..by number 10 spanner..and from both locks..dry the box of water..remove the insulation where u see many wires connected together ..u will see corrosion
...cut them fresh and join them together again..then re insulate them..problem fixed..never waste ur time and money with vag diagnosis..they will just throw many errors in ur face and not telling you to look for water or corroded wires
.i hope this help someone from unscrupulous audi dealers who may end up replacing the computer mother board..cheees +267 72 99 64 89..text me if this turns useful