Instrument cluster voltage regulator

Thanks for the answers guys. That's interesting. I thought for sure that was the limiter, but I'm by no means good with electrics so your guess is way better than mine. I'll test the red wire this weekend.

Do you have any pics of the regulator in the fuel gauge? I had the dash apart a few months ago but it didn't catch my eye.

Thanks!

Well friend it could only catch your eye if you knew exactly what to look for.
Typical gauges have 2 contacts that typically serve as mounting studs too.
Those are voltage in and sender out. A gauge with 3 contacts surely has something else inside. This is the case with many Chrysler gauges.
Early Imperials and others had the limiter housed inside their temp gauge.
The A-body rally panel and others had the limiter housed inside their fuel gauge. All these have 3 contact posts..
I've serviced 209 of these 3 post gauges during 6 years so I do have lots of pics and all sorts of helpful info ( much more than I can provide here ).
I'll add this... Please don't fall for the "bend a little thingy" do it yourself crap found on the net. It doesn't work.