Major Electronic Fault
12-13-2018, 02:16 AM
#1
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Major Electronic Fault
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??
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??
12-13-2018, 05:39 PM
#2
AudiWorld Super User
German car with electrical glitches. All I can say is good luck.
I had the battery not charging message a month or two ago; alternator pulley broke and was free spinning in both directions (should only free spin counter clockwise; clockwise should lock and spin the alternator).
Might be an issue with the battery or BEM (battery monitor, the thing hooked up to the negative terminal, which has a plug to it that you're supposed to disconnect before reconnecting it to the negative terminal, then reconnect the plug).
You can monitor current flow in VCDS (address 19, measuring block 19 or 20, iirc); I show a negative value when sitting with the car off and positive with the engine running. I assume these values are being measured at the BEM.
If the engine didn't stall but the interior went dead, that at least helps you some. You still had brake boost and steering? Tracing the no charging problem will be a lot easier than finding your short/ground problem that hosed the dash.
But I suspect you'll have to just start tracing the voltage to find the issue. What's the voltage at the alternator output to the alternator housing. Then at the 12v charging post in the plenum cover. Then at the positive post on the battery. etc...
I had the battery not charging message a month or two ago; alternator pulley broke and was free spinning in both directions (should only free spin counter clockwise; clockwise should lock and spin the alternator).
Might be an issue with the battery or BEM (battery monitor, the thing hooked up to the negative terminal, which has a plug to it that you're supposed to disconnect before reconnecting it to the negative terminal, then reconnect the plug).
You can monitor current flow in VCDS (address 19, measuring block 19 or 20, iirc); I show a negative value when sitting with the car off and positive with the engine running. I assume these values are being measured at the BEM.
If the engine didn't stall but the interior went dead, that at least helps you some. You still had brake boost and steering? Tracing the no charging problem will be a lot easier than finding your short/ground problem that hosed the dash.
But I suspect you'll have to just start tracing the voltage to find the issue. What's the voltage at the alternator output to the alternator housing. Then at the 12v charging post in the plenum cover. Then at the positive post on the battery. etc...
12-14-2018, 05:30 AM
#4
First thing I would check is to make sure that the battery cables are tight and you have a solid ground connection. Check the wiring to the alternator and make sure the contacts are clean and free of corrosion. If you have an intermittent connection somewhere it will cause the system to act flaky just as you described.
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