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My '52 M37 has wires 8 and 9 out of the regulator. The previous owner had an amp meter but it doesn't work.
What would be best in the cluster?
The easiest to interpret?

New voltmeter and rewire?
Check wires 8 and 9, maybe rewire or new amp meter?

Either way seems just as much work for me.

Wires 8 & 9 from the regulator are for an amp meter.

If you want a volt meter, just pick up wire 27 from the instrument cluster (it's grounded through the panel).

John Mc wrote: ↑Sun Mar 09, 2025 11:46 am Wires 8 & 9 from the regulator are for an amp meter.

If you want a volt meter, just pick up wire 27 from the instrument cluster (it's grounded through the panel).

Yes, thanks.

A volt meter is a better choice to know what is going on. An ammeter only gives rate. But, because I like to know both level and rate, I have both and mounted the ammeter under the dash in a small panel.

just me wrote: ↑Sun Mar 09, 2025 5:33 pm A volt meter is a better choice to know what is going on. An ammeter only gives rate. But, because I like to know both level and rate, I have both and mounted the ammeter under the dash in a small panel.

Thank you. I was leaning towards the volt meter.

I read that with a solid state regulator (which it has) the volt meter is required. The wires might be there in the harness but the regulator has nothing on 8 & 9.
Now, if that's true it explains what is going on.

This post got me thinking that I should do something about my ammeter that does little more than wiggle.

I picked up a working voltmeter from a friend and removed/insulated wires 8 & 9 from the ammeter. I had a 5 wire spider so I plugged 27 into the rear of the voltmeter and it's up and going, BUT I was curious will having 8 & 9 disconnected cause any unforeseen issues?

On another note I think I may have a regulator issue.
*On our initial test at idle the "new" voltmeter is right at the reference mark in the green area of the scale which matches the value of my DVOM of ~28v. *When I rev the engine the voltage drops to around 25v and the needle on the gauge dithers around quite a bit. I did check the grounds and found no issues there.
*Firing up the high beams and brake lamps has little to no effect.
*After running for some minutes the voltage returns to ~28v and the gauge fluctuations subside.

Any ideas what's going on here? It seems my regulator may be cycling or something???? I've put a ton of miles on the truck and have had no issues with the charging system so maybe adding a gauge was a bad idea !

Thanks

Andy

I'm on a 12V alternator Andy so I can't help on this one.
Gary

I'm on a generator and mechanical regulator. After warmup and the battery has recovered from starting, at idle I'm about 26V. Off idle I'm 28.4V. If I come near stalling the engine I hear the cutout relay cycle and it shows battery voltage.