My BMW 645ci E63 from Copart. Regulator replacement.

All the gauges were acting up, navigation was rebooting constantly if I would rev the engine. I did test the voltage and it did fluctuate from 11.5v when idling up to 17v when revving. That's a clear indication of the failed regulator. Most likely it was shot due to the multiple cases using the booster to start the vehicle (yes, those things are pretty sensitive) because original battery was completely dead.
In the other case I would probably replace the alternator as well, but since the car had only 29k miles - the original one should be perfectly fine.

[@aries6776]

Great video. I'm just about to attempt this on my 635d and it's good to have an honest video so I know to expect that it will take me about 3 hours!

[@dlamontw]

that was fantastic thank you

[@travisbarrette6876]

Did this ever give you a trans malfunction message?

[@HETPEZB]

Indeed it did. After replacement- retransmission malfunction warning gone.

[@travisbarrette6876]

@@HETPEZB okay, i just bought a 645ci and get this message when im running my accesories and after more research alot of people said it was the alternator. Im stuck between replacing the alternator or the voltage regulator. With the vehicle running and nothing else turned on it reads 14v. But with accesories on it will read 12.4v

[@HETPEZB]

How much does it read when you rev? P.s. start the replacement with a least expensive part - regulator.

[@destroyer6867]

@@travisbarrette6876 so what did you end up replacing? If you could remember

[@travisbarrette6876]

@@destroyer6867 i unfortunatly never got doen the the problem. It was really prone to doing it when doing wot pulls