Voltage gauge reading low

[Michael]

Problem that has annoyed me for a decade. My voltage gauge always reads low. My multimeter shows my battery at 13.4-.6v at idle and around 13.2-3 with AC engaged.

My gauge however will show about 12.7 at idle and about 11.5v with AC on. Even less with lights on etc. It's always been this way but I know my charging system is fine and I know the gauge is known to be quirky. Is there anyway to recalibrate it or even pull the needle and reposition it to a more accurate location? At this point I just may buy a new gauge unit as my temp gauge sometimes will peg and get stuck at 12 o'clock when I turn the ignition off. I know these 2 share a ground. Is it possible a corroded ground could be the culprit?

[jackb]

The fuel pump shares a ground w/ the instrument cluster. You can reground it at the inertia switch to one of the bolts that secures the body to the frame by the drivers right leg. Probably won’t make a huge difference at the gauge though. Neither would a new gauge- the ground wiring across the whole car is so shitty that what the gauge gets at that location is accurate. As long as you know you are charging correctly at the battery/alternator, and you know your gauges baseline, so be it.

[Ron]

Corrosion or any bad connection along the volt gauge's circuit, ground or feed, could cause the gauge to read low. (Wiggle the IP plugs, check the fuse/socket.)
I would guess it has as much to do with our quirky gauges as anything else, as you say. So common that it wouldn't be worth trying a new unit, imho. There are ways to easily trick the needle to move lower (but not higher) so that it reads correctly at a given voltage, but that would throw readings at other values way off. So I'd agree with just live with it.

Now if you knew a talented painter who could change the "13" to a "14"....

[dmcnc]

Dedicated ground wire spliced on to the binnacle connector for the gauge did the trick for me in terms of gauge accuracy (for an analogue gauge). Separately, Dave M's Idle ECU has the AC bump, which keeps the idle 100 RPMs above the normal setting while the compressor is engaged. That gives my car enough kick to stay above the 12.8 waterline with everything turned on at idle.

[Ron]

That's a good idea...bypasses all of the old connections etc. You might do the same thing for the positive side (but taken off of the (W)hite wire feeding Aux Relay 2 instead of the battery).

[Bitsyncmaster]

Yes moving the ground on the inertia switch to frame ground will make your gauge read about 0.3 volts higher.

[opethmike]

Problem that has annoyed me for a decade. My voltage gauge always reads low. My multimeter shows my battery at 13.4-.6v at idle and around 13.2-3 with AC engaged.

My gauge however will show about 12.7 at idle and about 11.5v with AC on. Even less with lights on etc. It's always been this way but I know my charging system is fine and I know the gauge is known to be quirky. Is there anyway to recalibrate it or even pull the needle and reposition it to a more accurate location? At this point I just may buy a new gauge unit as my temp gauge sometimes will peg and get stuck at 12 o'clock when I turn the ignition off. I know these 2 share a ground. Is it possible a corroded ground could be the culprit?

You can fix this by doing an LS swap.

[Michael]

You can fix this by doing an LS swap.

But I'm not gay

[opethmike]

But I'm not gay

Not yet...

On an unrelated note, does this smell like chloroform to you?

[Michael]

Bi curious is not gay!