Instrument cluster-volt guage, Why don't they ever work?

[mrtleavitt]

On every old Ford I've seen the volt guage never works. I'm talking about the one that is an actual guage on my '72 truck that's right under the fuel guage. I've noticed there is an extra place for a wire to plug into the voltage regulator. Did these trucks come not hooked up from the factory? What's the deal? How hard would it be to get mine working properly?

[basketcase0302]

mrtleavitt,

Have you tried verifying the wiring to the gauge?
Here you go:
http://www.fordification.com/images/sch ... _quick.jpg

To test the gauge shouldn't be that hard either, (12 volt dc, put a ground to one terminal on the gauge and a hot to the other).

Hope this helps.

Basketcase

[Thunderfoot]

One thing that is misleading on these old Ford's is that it is not a Voltage gauge but an Amp gauge... so they don't move much off the center position.

If your battery is charged up good and you don't have anything turned on that draws current (lights, wipers, big radio, etc) then it will not show much of a move (mybe a needle width)... If all that stuff is on it should move over just a little more but still not as much as you would think...

With the stock small amp (45A) alternators they don't move the gauge much.
I went to a 100A in my car and it made the gauge move twice as far when it is under a good load compared to before, but that is still only about 1/8 of the range on the gauge...

[bluef250]

Read this thread - http://www.fordification.com/forum/view ... ight=shunt . None of the charge gauges on Ford products that used this system worked well and lots of people complained, but Ford did not change it. I still I'm planning on changing the sensitivity by changing wires when I make some changes and see if it will change the gauge movement.

[fitzwell]

If you have a stock alt & an ammeter, you MIGHT get a slight movement. If you upgrade to a better (65 amp & up) alternator, you need a voltmeter. Period. Ammeters are fine in vehicles that have 35 amp alternators. Even a unit that "samples" the voltage, with a high output alternator, you're asking for trouble.