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Old 10-25-2012, 09:02 AM
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540 M-Sport 540 M-Sport is offline
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Location: Seattle, WA
Join Date: Apr 2004
Posts: 4,958
Mein Auto: 01' 540 M-Sport cdn, F355
Originally Posted by YinD View Post
I did perform an alternator load test. I did not think to turn on the wipers, high beams, or full fan
I turned on:
a/c to auto (the fan went to about 1/2 speed)
rear window defroster
front driver seat heater max heat
headlights and fog lights
The readout started at 13.8 V and with each system it went down to 13.4 V

Reading some other threads on alternators, it sounds like maybe the brushes in the alternator are getting old. Records show that the alternator was changed at 78,681 at a BMW dealership. Car is at 135,000 now.

Am I in the right direction?
BMW warrantees the replacement alternator for 'life", if they install it. Two years if you install it yourself. I am unsure if that is a transferable warranty, but worth checking with your local BMW dealer. Sounds like you have the reciept, but even if you did not, it should be in their national database.

I am unsure if you have a problem with the alternator or not...but the only time I have had a "trans failsafe" warning that I can recall, was when my alternator failed at around 80k miles.
Factory M-Sport package with factory installed M-tech bumpers, factory Bluetooth, factory M-Audio 10" dual voice coil subs, Homelink, M5 rear stabilizer bar, Bilstein B14 PSS coil overs, Stop Tech ss brake lines, Akebono Euro Ceramic brake pads, oem Brembo and Zimmerman rotors, Dinan Stage 1 software, Strong Strut front upper stress bar.

Last edited by 540 M-Sport; 10-25-2012 at 09:08 AM.
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