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Discussion Starter #1
So normally my volt gauge reads around 10 volts when I start my truck up, then once the GPR clicks after about 10 seconds, it reads right around 14 (needle straight up and down).

Today, it didn't return to 14 volts. So it's staying low around 10 volts (needle is just under the N in Normal).

I'm trying to figure out if it's alternator, the GPR not clicking off, or something else. Thoughts?

Thanks

-MK
 

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Demon Dually
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Test the GPR by checking for 12 volts give or take at both large terminals on the GPR after the GPR has had time to cycle through. If both are still powered then the GPR is stuck on. If the GPR tests ok then check the charge lead coming from the alternator. If that checks out ok take the truck to a parts store that can check your charging system with the alternator in the vehicle. They will be testing your batteries at the same time.
 

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Busted Knuckles
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Had the same problem this winter. I load tested the batteries and Replaced them but turned out it was my alternator. If that turns out to be the case with you I'd go with a 200 amp one from DB Electircal! Just try and guess what that fourth gauge is :hehe:
 

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Discussion Starter #5
Something else to add: this happened all of a sudden. I drove it home from work and it was fine. An hour later I took it to the hardware store, and the gauge jumped up like normal for a split second, then returned to 10V. Since then it's stayed there.

Normally don't alternators die slow?
 

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I would check the relay before ordering the alternator. It could be one of a couple of things. One is that the pcm is giving you problems and sending a ground to energize the relay. Two is you may have a wire going to ground that will energize the relay. You really don't even need a meeter to check it just a test light will do.
 

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Simple test - start and run the truck for a few minutes, 'til you know it's warm enough that it won't need the GPs. QUICKLY disconnect both battery negatives, and then take the "big" always-hot lead off the GP relay. Reconnect batteries, restart the engine. At this point, there should be NO GP engagement, so even the lame dash volt gauge should point right-of-center. If it does, then your alternator is _probably_ okay, and the problem is in the GP circuit - relay sticking or PCM not shutting it down when it should or some such. If the gauge still reads low, that suggests a bad alt or main battery wiring.
 
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