[Vwdiesel] Alternator question
mikel at buncombe.main.nc.us
Wed Jan 31 19:22:24 EST 2007
>Date: Tue, 30 Jan 2007 09:14:11 -0500
>From: MWoodland at Dentsply.com
>Subject: [Vwdiesel] Alternator question
>To: vwdiesel at vwfans.com
> <OF7E5A829F.6DEB88ED-ON85257273.004E0DA0-85257273.004E3486 at dentsply.com>
>Content-Type: text/plain; charset=US-ASCII
>I noticed the lights flickering on my Jetta ('91 NA) last night, and tested
>the voltage at 13+ volts DC charging, and almost 30 volts AC.
>My first guess would be that I lost a diode in the bridge rectifier, which
>is probably inside the alternator, and not part of the voltage regulator..
>Haven't yanked it apart yet.
>Does this sound right?
unfortunately, no, sorry...
I've never thought to check for AC voltage on a bad alternator before,
but I do know that, even with a bad diode, the the alternator can charge
the battery while it's running, and then it usually discharges the
battery while the car is parked.
I went out and checked my Jetta, and the only place I found any
significant AC voltage was on the W terminal, and it was somewhat less
than 10 volts. I also noticed that it is putting out about 14.2 or so,
as opposed to its usual 13.5, and at first I thought 'hmm, it must have
gotten stronger', but then I recalled that when the meter's battery
starts getting low the readings tend to be higher - just thought I'd
throw that in ; )
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