Unfortunately, I really can't pinpoint when it started, but here is the sequence that sticks in my head.

1) Bought the M5 in spring of '12 - love it!
2) Took it to the track a few times - REALLY love it!! (No dash issues during summer)
3) Had a Dension installed (and a few other things), Dension didn't work properly (for another post). Specifically couldn't get audio through Dension aux, Dension bluetooth didn't play well with native bluetooth, also I didn't get an A2DP unit for streaming music over BT, which is what I really want.
4) Noticed dash go completely blank while driving sometime in late summer / fall
- Intermittent, seems to happen more frequently when accelerating hard but still happens sometimes while just coasting
- Whole dash just goes completely blank - instruments, NAV screen, HUD, everything
- Car continues driving, don't notice any change in engine, acceleration continues smoothly if accelerating
- Dash is usually out for 1-2 seconds, if that, then comes on again
- SOMETIMES, but definitely not all the time, errors greet me when the dash comes back on
- Sometimes ABS error, sometimes Servotronic error, sometimes check battery connection error, sometimes other errors. If Servotronic error comes on power steering goes out (but only after the dash comes back and the error message hits the screen)
5) Hit a pothole pretty hard, did some damage to suspension, had shop replace a few things, covered by insurance
- Mentioned the dash issue, asked them to poke around while under the hood, but it's so intermittent can't make it recur, shop fixed up suspension car and test drove, no dash issues, returned to me
6) Dash issue comes back, worse than before (more frequent)
7) I take out the Dension unit, thinking 'it's clearly wired wrong, maybe that has something to do with it?'
8) Wiring now all back to normal from before Dension install, but still have the dash going out on me, still very frequent
9) Shop says maybe it's the battery or battery connection, thinking I may try to swap in a new battery this weekend but want to check if anyone has better idea first
- Did some searching around online, found a few vaguely similar issues but no compelling similar case.

Thanks in advance...

Ottac

 

Battery or Alternator
Bring it to Motorcepts they will take care of you.

You can check THIS thread too.

 

Thanks Andy!

Yes it seems like a battery issue. Hopefully that's the culprit. Stop by us and we will run a full diag free of charge