battery gauge going crazy

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Sep 18, 2012 | 02:43 AM

sunbelt57

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battery gauge going crazy

I was going to work today in my 92 F150 and the voltage gauge started pegging along with the battery idiot light flashing on. I pulled over to look under the hood and check the batteries and found nothing obviously wrong. I started back up again and it was fine. It did the same thing in almost the same spot on the way home but this time the gauge was really bouncing around and the transmission went out of and into gear. I guess the tranny is computer controlled. I have the factory service manuals. I was just wondering where to start. Probably a short somewhere?

Sep 18, 2012 | 06:32 AM

Franklin2

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Take the battery + cable loose, and then take the wires off the alternator and check them for being loose, melted or corroded. Simply taking the connections off and putting them back on may fix it.

Sep 18, 2012 | 08:32 PM

sunbelt57

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Thanks Dave. As a matter of fact, I just put new post connectors on the other day but it was because I was wiring to an inverter so I'm hoping that's the problem.

Sep 18, 2012 | 08:40 PM

Muffinman

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From: Dallas, Texas

You got a bad alternator get it checked. Its over heating and the voltage regulator is going out. If you drive it to much it will burn up the wiring or bulbs, if it gets above 19 volts.

Sep 18, 2012 | 08:46 PM

sunbelt57

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That makes sense. If it was shorting the gauge would go to zero instead of up over 18v.

Feb 20, 2025 | 07:31 PM

Jacksonham

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Quote:

Originally Posted by sunbelt57

That makes sense. If it was shorting the gauge would go to zero instead of up over 18v.

I know this post is years old but I have a similar problem. My voltage is slowly rising on my gauge in the cab. Starts out slightly above where it should be and slowly rises. I recently put in a new alternator which should have had the built in regulator. I can only imagine that alternator has somehow gone bad as it it slowly rising and not jumping around. Any thoughts anyone?