I feel like this is a bit of a dumb question but with it being 14* outside and needing my car to get to work, I'd rather be safe than sorry (and I troubleshooting in 14* is no fun). Realy maybe this thread should be called valeo or bosch alternator but anyways my battery light came on while driving home yesterday. I shut as many loads off as I could and made it home fine. I put a meter on when I got home (I know I can do that the computer but I had a meter handy). With the car off my voltage was 11.3V running I was 11.0V headlights on 10.9V etc. Its clearly not my battery and is an issue with the charging system. I'm just not sure if I should replace the alternator (I assume they come with a new regulator) or just the voltage regulator. I believe on these the voltage regulators house the brushes which leads me to believe that I would be best off with just the regulator. But it would be nice to have confirmation on that if any of you have had a similar issue.

It sounds like my car either has a valeo alternator or a bosch and they are VR's are not cross compatible. Is there anyways of determining (build date, options, vin, etc.?) what I have without inspecting it (car is 30 miles away at home) so I can get this on order now. I need my car to be back in action for my commute to work.

Thanks a lot!!

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2004 e53 m54 with 6spd manual