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rpmdiag
rpmdiag, Tech and Instructor
Category: BMW
Satisfied Customers: 6863
Experience:  Since 1975
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I have a 2001 BMW 325CI and I replaced the battery and

Customer Question

I have a 2001 BMW 325CI and I replaced the battery and alternator because they were bad I put the new alternator in and I'm checking the voltage in the voltage is fluctuating from 13 to 14.90 down to 12.98 what could be the problem
Submitted: 1 month ago.
Category: BMW
Expert:  rpmdiag replied 1 month ago.

Hi, I'm Ron and I will be helping you today.
Stand by for a moment while I prepare your answer.

Expert:  rpmdiag replied 1 month ago.

A bad voltage regulator will cause that. The regulator may be external or controlled by the computer.

Thanks, Ron

Expert:  rpmdiag replied 1 month ago.

If you are satisfied with my answer, I would greatly appreciate a 5
star rating now and I will still assist you after you have rated me
too if another question pops up. I don’t get credit for helping you
until you rate me.
Thanks again, Ron

Customer: replied 1 month ago.
If it is that how would I know and where's it located?
Expert:  rpmdiag replied 1 month ago.

It's external of the alternator and located inside the computer. You can attach a scan tool and watch its' functionality that way to see how or even if it's working.

Thanks, Ron

Expert:  rpmdiag replied 1 month ago.

If you are satisfied with my answer, I would greatly appreciate a 5
star rating now and I will still assist you after you have rated me
too if another question pops up. I don’t get credit for helping you
until you rate me.
Thanks again, Ron