Thread: battery light
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Old 12-07-2012, 05:42 PM   #14
Cayne23
Registered User
 
Join Date: Sep 2012
Location: forest hill, md
Posts: 550
My Ride: 2002 m3 convertible
I just saw on youtube how to test the battery and alt using the test mode in the car. With the car off my volt reading was 12.5volts. Started the car and it went uo to 13.9-14.0. Turned on the heat, same thing. Radio on, stayed the same. Turned on headlights, 13.8-13.9volts. Turned on rear defrost and front defrost, 13.6-13.5volts. Turned on both seat heaters full blast, 13.5-13.4volts Reved the engine,13.7-13.8volts. Idled down, 13.5-13.6 with everything on. Is the alternator slowly starting to go?
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