Gauge issues

I’ve got my ‘68 with a mechanic installing new original style gauges in my instrument cluster (fuel, temp etc.). They’re getting voltage from the regulator but my guy is telling me that it’s a 12 volt system while these gauges appear to be 6 volt gauges (they say 6V) on the back. Is it correct that everything should be on a 12V system? The gauges were purchased at Jeff’s Bronco Graveyard so they’ve gotta be the appropriate gauges. The gauges are not reading properly yet are ground properly I’m told. Not sure what’s going on. Any help anyone can provide re: the voltage issue would be appreciated.

Ok. After a little research, may be a bad voltage regulator? Isn’t it supposed to reduce voltage from 12 to 6 volts?

Hi, the instrument cluster voltage regulator has 12 volts going in, and reduces that to @ 6 volts, which is a pulsing, meaning on, off, on off. You can see the 6 volt pulsing current at the back of the instrument cluster, and at the end of the sender wires feeding the water temp sender, oil pressure sender, and fuel gauge sender. Good luck

So if the regulator is sending 11.8 volts to the gauges it isn’t functioning properly and would need to be replaced, yes?

Sounds like it to me. But first make sure that the gauges are connected before taking that reading.
A modern electronic regulator will send out a simple, non-pulsing voltage signal around 5v or so. A regular one, as described by Ron will send out the pulsing signal that's often hard to see on a digital volt meter. If you have an analog meter and the needle sweeps between 4 and 8 volts, it's still good.
But because the old style may perhaps vary by load, if you test it without having it connected to the gauges it might give you a false reading.

The pulsing action does not show up on the gauges because the workings are dampened to only show the average. You can see this action any time you turn things on or off, as the needles sweep slowly to where they will finally settle.
Use a regulator on an aftermarket gauge and you'll just get the needles bouncing back and forth a lot!

Good luck.

Paul

Oh, and the originals (and many replacements) are adjustable.
There is a tiny little flat knob rheostat thingy somewhere on the back between the two connectors that you can turn. It's usually held in position by some epoxy stuff to keep it set after initial setting at the factory.

Not sure if it's got the range to bring it all the way from 11.8 down to 6-ish, but it might be worth a try.
Assuming it's not more expensive to have them fiddle with it than it is to just have them replace it that is. Easy decision to mess with things when you're doing it yourself. When you're paying a shop by the hour, not so much.

Paul

So got new gauges in with new regulator and the new regulator is still sending 12ish volts to the gauges I’m told. And the gauges are connected like mentioned above...

tholmes6 said:

So if the regulator is sending 11.8 volts to the gauges it isn’t functioning properly and would need to be replaced, yes?

Click to expand...

If the regulator isn't grounded it won't drop the voltage. Ground it then test it.

It is grounded.

Interesting. Perhaps test the it with a home made jumper wire grounding the mounting screw of the voltage regulator directly to the body somewhere. Not to the dash though, as it could have a weak ground too. Do it directly to the firewall perhaps.

And speaking of the firewall, is your battery grounded to the body as well as the engine block? A necessity is to have a wire going straight to the body from the battery. And a really good practice is to upgrade your stock grounds with a strap or wire from the back of the intake manifold to the firewall.

This is a long shot for your gauges, since the regulator doesn't use much current, so really should not need much of a ground to function properly.
But it can't hurt to try it!

And last, but not least... I'll go back to one of our Bronco-mantras, and that is that "new' no longer means "good" when it comes to parts. So your brand new voltage regulator could be faulty.
Since most fail by putting out too little voltage rather than too much, it would be quite the coincidence for your old one to fail to 12v output, and your new one to do the same thing.
But it's not impossible either, so should not be ignored.

As a bench test you can connect a battery to both of your regulators. Negative to the case, positive to the input connector. With it grounded directly to the battery like that, you should see exactly what the regulator is doing independent of any gauges.

Hmm, and speaking of gauges... Maybe Viper or someone knows this, but if one of the sender wires is shorted directly to ground without going through the sending unit on it's circuit, what would that do to the regulator output?
Seems like it would still only put out as much as it's capable of, so if it's putting out only 5v it should stay that way. But if shorting to ground causes it to just pass the full voltage through it, you would see the same on the output as you do on the input.

Maybe one of the experts will chime in on that possibility.

Paul