The instrument voltage regulator is nothing more than a bimetallic strip that makes and breaks the connection between the 12v source and the gauges. It supplies an average 5v (approximately) to the gauges. That is what heats up and cools off, nothing to do with the gauges heating up.
Why did they use that? It's cheap, it works and it is sufficient unto the day. Nothing more. I am sure it was developed in the 50's when they converted to 12v and your other option was a vacuum tube, not optimal at all. remember transistors were barely 10 years from having been invented. By providing the gauges with a run voltage less than 12v you can eliminate the effect of the charging system voltage fluctuations on the gauge readings.
If it sticks closed those gauges will peg and eventually destroy their selves from the heated overload.
Wondering if this might be my issue ??
I have a 71 Duster with the factory rally dash. The issue I have is two fold.... first the dash lights are very dim but the radio lights up good. Tried a new headlight switch thinking that might be the problem. Recently the oil pressure gauge reads high all the time. Starts out okay, especially at idle but after a while and the engine is at normal temperature it reads high. Needle is reading at the very extreme high point. Also the temperature gauge is reading higher than usual but not to the point that it's dangerous. Sometimes I think the Alt guage is off but it seems to be acting properly. Gas gauge always seems to go down quickly especially at these prices. LOL. Fuel gauge seems okay. Just wondering if the volt meter that your talking about is also what is giving me grief ?? It's never been replaced by me in the 25 or so years I have owned the car. Thanks for any help.
Bennoel
