O/T GMC truck volt gauge problem odd

old · Oct 14, 2012

Friend stopped by yesterday to have me install and alternator in his truck and do a new belt at the same time. Real easy job once I found it was metric. Truck is a 200? Any how after I was done I started it up and the volt gauge went up to around 19 volts or more. About 45 minutes later when he walked back in from walking around looking for arrow heads he starts it up and the volt gauge pegs. With it not running the battery reads 12.3 or so volts and with it running my volt meter reads right at 14.3 or so volts so what the heck is going on. I did unhook the battery when I was working on it to be safe and not short something out
Thanks

Michael Soldan · Oct 14, 2012

Thers nothing wrong with 14.3..up to 14.8 is OK

old · Oct 14, 2012

I think you miss the fact the truck built in gauge reads 19 plus but my hand held meter reads voltage is correct so truck has problem some place

MARK ROBKE · Oct 14, 2012

I would pull the dash and measure the voltage at the guage, and go from there.
Mark

JDseller · Oct 14, 2012

Just a bad volt meter in the dash. I see them all of the time. It seems like volt meters are not very rugged. I used to think they would be nice on farm equipment but I found out they don't last very long in the rough environment.

If your meter show it is not over charging then I would not worry about it unless he wants to replace the dash cluster.

wascator · Oct 14, 2012

My 2000, 2006, and 2012 GMC pickups all did/do this. I asked about seeing the differences in the voltmeter and learned it's normal.

fixerupper · Oct 14, 2012

The voltmeter on my IH 1086 has been goofy since day one. If it doesn't show a charge I check it with my VOM to be sure it isn't lying to me and most of the time it is lying! Jim

Anonymous-0 · Oct 14, 2012

Hi old I fix electronic medical equipment so here is what I think. All electronic meters including your hand held have shunt resistors or shunt circuits that sample the input. It sounds like the meter on the truck dash has malfunction here. If you have to replace the cluster to fix it try disconnecting the volt meter only and install an aftermarket under the dash. Any of the switched outputs from the fuse box should work okay for a source. I would probably try to find the positive for the radio power to use.

Jon Hagen · Oct 14, 2012

My 92 chevy pickup has the typical junk quality panel gauges. The voltmeter typically reads several volts low until I give the top of the dash right above it a flat palm slap. That will bring it around for a few hours or days, until it needs another good slap. The panel is hard to remove and very shoddy quality. I know the alternator is working correctly when measuring voltage at the battery, so I just ignore the crappy dash gauge.

old · Oct 14, 2012

Ya the volt gauge in my 1980 Chev truck is one that reads low some times till I hit the dash and then it goes to where it should. I figured it was pretty much the same thing on my friends truck but I have found it is better to ask and see what others have found before just writing it off

MarkB_MI · Oct 14, 2012

2003-2006 GM pickups have defective gauges. The voltmeter is an annoyance, but all the gauges including the speedometer are buggy. There are several guys who will replace all the gauges in your instrument cluster for much less than the cost of a new cluster. Here's one of them, my son used his services and was quite satisfied.
Dr. Speedometer

Rodney Middleton · Oct 15, 2012

Feild windings in the alternator have shorted out . I had it happen to me. passed all bench tests until it was installed . It took forever to figure out. Rodney

MarkB_MI · Oct 15, 2012

Not an alternator problem. He says it reads right at 14.3 volts per his multimeter, which means the gauge is bad.

O/T GMC truck volt gauge problem odd

old

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Michael Soldan

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old

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MARK ROBKE

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JDseller

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wascator

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fixerupper

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Anonymous-0

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Jon Hagen

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old

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MarkB_MI

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Rodney Middleton

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MarkB_MI

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