Volt gauge reads voltage for a minute then disappears

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Feb 12, 2019 | 08:24 AM

Superdrag73

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Volt gauge reads voltage for a minute then disappears

Driving in to work this morning my volt gauge dropped onto the bottom peg. It ran fine and the lights were a little dim but still good enough to not stop. The truck starts up and runs fine every time, but after about a minute of driving it drops to zero on the gauge again. I checked for bad connections and didn’t find any. Sounds like alternator to me. Ideas?

Feb 12, 2019 | 10:41 AM

HeyYou

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From: Clayton MI

Wait until the gauge drops to nothing, and put a meter on the battery. What's the voltage there?

Feb 12, 2019 | 01:13 PM

Superdrag73

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Quote:

Originally Posted by HeyYou

Wait until the gauge drops to nothing, and put a meter on the battery. What's the voltage there?

I didn’t do that, but when it’s running if I disconnect the battery the engine dies. That tells me it’s the alternator. I could be wrong.

Feb 12, 2019 | 01:20 PM

HeyYou

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From: Clayton MI

Quote:

Originally Posted by Superdrag73

I didn’t do that, but when it’s running if I disconnect the battery the engine dies. That tells me it’s the alternator. I could be wrong.

That test worked on older systems, but, isn't a valid test on newer systems.

Feb 12, 2019 | 03:30 PM

Superdrag73

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Quote:

Originally Posted by HeyYou

That test worked on older systems, but, isn't a valid test on newer systems.

I was afraid of that but a new alternator seems to have fixed it. The thing that threw me was, I would expect the gauge to read 12 volts if the alt wasn’t charging, not on the bottom peg.