low voltage reading

[k7king]

I have a 55 chevy I built 6 years ago. This car has a FI 502 computer controlled 4l80e tranny. Dual Electric fans Power Windows and A.C. The car is wired with a Ron Francis wire kit.

the car has been fine for 6 years and all of a sudden the volt gauge on the dash seems low. I checked voltage coming out of the alternator at 14 volts. At the battery it is 13.6 volts. when running the voltmeter says 13 .6 volts. Then I turn on the AC and the headlights and the voltage slowly starts going down on the gauge. It ends up being about 12.5 volts while idling. I also hooked a voltmeter up to the fuse box and it shows same as the gauge. I took the alternator off the car and had it tesed. They said it was good. I load tested the battery and it showed good. I checked and cleaned all the grounds on the car.

Any suggestions on what to look at next?

Thanks in advance

[CHILI442]

Your volt meter is apparently wired in with everything in your dash, and showing you the 'dash' voltage. I had this problem for years. The easy fix is to get a cheap relay from a parts store or Radio Shack and wired it in-line with a power line directly from the battery or junction (horn relay on my '68 Olds) to your gauge. Then wire the relay so that whey you turn the key the relay is energized and lets current flow from your source to the gauge, and therefore show you true system voltage. Problem solved. I hope this wasn't too confusing. I wish I had a schematic handy but I don't.