Help! Voltmeter Reading 19 Volts

C

cmatt

New member
Feb 22, 2013
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Perplexed by this one. Five days ago the voltmeter needle climbed to around 19V. It does fluctuate some, but never below 16V. Had things tested at Advance Auto. It showed everything within parameters, but still gave a result to replace the battery. It was an Optima Red Top I installed in Feb of this year (manufactured 1/2013). That battery replaced another Red Top I had in there since 2006 until it died. So I put in another Red Top (under warranty) and no change with the battery gauge.

Ideas where to check next?
 
All signs point to voltage regulator, since you didn't specify what kind of vehicle. I'm going to assume it's late model and the alternator is internally regulated. So that means time for a new alternator.
 
First. Was everything tested off the car? Readings can be false while tested on the car. I had it happen numerous times while working at a parts store.

Have them bench tested.
 
Sorry about that. It's a 2007 GMC Sierra Classic Crew Cab SLT Z71 with the flex fuel 5.3.

Jared, do you mean to have both the alt and battery bench tested?
 
Wonder if the initial battery essentially dying before replacement would contribute to damaging the alt?
 
I guess so. I actually replaced the original alt in early 2008 with a 255Amp from rat ron (member from the other gm site). I hate to replace it, but if it's done, so be it. I guess I can grab a 160amp.
I'll get the batt and alt bench tested and report back.
 
Is this 19volts a reading on the dash cluster or on a voltmeter? If its the cluster, it may be a bad stepper motor. But like suggested, have everything bench tested.
 
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