Voltage Gauge Reads High

[edgarollins]

So this interesting item popped up a little over a year ago.  Subject vehicle: 1978 C20.  While the engine is running, the voltage gauge reads at the bottom of the high voltage zone.  Tested output voltage at the (newish) alternator and have a steady 14.3v.  Anybody else have this issue?  Not really concerned since I know what I'm getting from the alternator, just would like to get the gauge working normal.

[LTZ C20]

Sounds fine to me being middle mark on the gauge is 13 volts and the gauge and the wiring and the truck is how old. From 1978.

[enaberif]

Sounds fine to me being middle mark on the gauge is 13 volts and the gauge and the wiring and the truck is how old. From 1978.

I applaud people who want to keep these trucks looking as OEM as possible and using all the stock gauges but you make a very valid point that a lot of people need to understand.

[LTZ C20]

That's also why the gauge has a range, anything that is in the middle area and not in the yellow on either low or high side is normal.

Mine reads 13 volts and down to the bottom of normal depending on what I have turned on, but I can also look at the ECM data for my fuel injection and see that's it's actually higher a little than the gauge. Again gauge is original and so is half of the wiring. If the gauge reading is all your concerned about, start the truck and take a reading with voltmeter across the negative and positive battery cables, if it's 13-13.5 volts up to 15 volts you should be fine. You should have a similar readying of you do the same test the battery ground and positive charge back wire on the back of the alternator.

[hatzie]

Check the ceramic bias resistor on the back of the gauge canister for loose nuts. 
Add external tooth star washers under the nuts JIC the printed resistor connection has worn off the ceramic.
Worst case swap the gauge with a different unit.