I have a 2005 530i. This week my car has been completely shutting down electrically while I am driving. The engine continues to run and sometime stutters for just a second but the stereo cuts outs, idrive screen goes black, and the speedometer and odometer go to zero. After a second or two the electrical system comes back and the idrive screen shows multiple errors including...
1. Dynamic Drive Failure
2. Active Steering Failure
3. Brake bads at minimum depth
4. Set Time and Date (I lose the stored time in the car everytime this happens)

I continue to drive and all systems reinitialize after about a minute. This only has happened to me at speeds below 30mph.
A month ago I had my voltage regulator off the alternator replaced because I correctly suspected I was getting voltage spikes at its output. This didn't correct the problem and I them had my local BMW dealer drive the car around for 3 days and of course it had zero faults. It seems all the errors are associated with devices that use the hydraulic system. They checked the hydraulic system and said there was no leaks and the fluid was fine.

ANYONE EXPERIENCE anything like this. Any ideas? Please help.

 

I'd be willing to bet your battery is weak and the electrical management is performing partial shutdown of non-essential subsystems and accessories to conserve power. Have the battery checked as well as alternator, charging circuits, etc. Just a guess though.

I recently had my date/time need to be reset immediately after cranking the car to start it. Also I noticed the radio would go silent while engine was cranking (not normal).... both are clear indications that the battery could not power the starter and accessories concurrently. I put the battery on a Battery Tender Plus charger overnight, and the symptoms went away. This was not caused by faulty alternator, etc. It was simply due to the fact I was not driving the car enough in the winter to keep the battery fully charged.

 

You need a new alternator. Something similar happened to me and this was while i was going to the dealer too. They covered it under warranty. So, tell the dealer to replace your alternator. =)

 

Could it be a bad ground somewhere? I always thought an alternator doesn't fail gracefully, its either working or not.

 

I call altenator aswell.

 

That has happened to me. Its your battery, check your connections to your battery!!!!!
When that happened to me I was getting my speakers replaced and the idiots at the audio shop didnt secure the connection.