My voltage jumps around from 13.0 to 14.0. It usually starts in the normal range,~13.8, but shortly drops to 13.0-13.4 and pretty much stays there with the occasional excursion upward. Is it the alternator/regulator or could a faulty battery cause the regulator to freak out. Starting feels pretty normal.
Thx Mike
Are these readings based on your dashboard voltage gauge or an actual voltage reading at the battery with a voltmeter?
Doc
I have a scan tool
OK, in that case, sounds like the alternator is starting to fade on ya'. It should be reading a pretty constant 13.8-14.4 volts at idle, measured at the battery. If you have a DMM, you could always measure voltage at the battery and then at the alternator positive to see if you might be getting some current loss between the alternator and battery. I'd also check your main grounds and make sure they're clean and tight. Year make and model? Mileage?
Doc
Duh, guess I shoulda posted the obvious the first time :)
96 Silverado, 155K already replaced alternator once. Will the electrical test they do at the parts store tell the whole story? Or, should I just do a load check on the battery and if good replace the alternator?
That would be my approach, after making sure both cables from the battery are clean at both ends, and, check any block to frame ground cables.
I have a 97 blazer and am on alternator #4 at 127k miles. They are all Delco "new" units (not labelled as remans). I bought the first one since it fell below the warranty deductable at the time, and keep the receipt(s) in the glove-box. It has a lifetime warranty, so only bought one, other than the hassle of changing it.
For me, they just fail randomly and suddenly - no output, the "battery" lamp comes on and the volt meter takes a dive.
Never had one fail mechanically (bearings).
That's interesting as I've never had one fail electrically! All of mine puke their bearings long before the output is dwindling. FWIW, the Duralast Gold alternator I bought at Autozone (new, not reman, lifetime warranty) has
4 years and 80,000 miles on it and still running great. Cost me something like $80 IIRC.Doc
>Just replaced the alternator in my '99 Suburban a few weeks back at 83K miles. It was just fading off and began to really fade one night! Took about a quarter mile to get back around 13 volts after a stop! That same night the bearings began a awful whine! So I had both experiences in one! I too put in the AZ Duralast unit for around $80.
Have something to add? Share your thoughts — no account required.
Ask the community — no account required