The Stovebolt Site Forums The Shop Area The Electrical Bay GMC gas gauge

Is anyone out there familiar with the wiring on '55.2-'59 GMCs, specifically the gas gauge? I want to use one of these (I have two) in my '54 GMC, as I figure they are built for 12 volt operation. Is this assumption correct, or do they have some sort of voltage reducer from the factory? Which terminal is which? They aren't marked and I don't have a '55.2-'59 wiring diagram.

It is my understanding that GMC went from 6v pos.gnd to 6v neg.gnd in '54, and at the same time changed to the round solo gauges instead of the cluster gauge. The '55-TF series was 12v neg.gnd, and despite the fact that they look identical the fuel gauge would have to be altered from the factory for 12v. I doubt you'll need to add a reducer if they're TF gauges.

IIRC, the (+) post is behind the E; the tank sender connects to the post behind F. I trust someone will jump in with corrections if I'm backward (again).

Thanks, Hedge. I'll check out the terminals and see what happens.

IIRC, all 6v GMCs were positive ground. Not that that matters, trying to get away from 6v is what this is all about.

Don't forget the trusty 7806 regulator! There is also a positive ground version (don't know the #), and another good one is the 7808 which puts out more than 6v but can be combined with a transister to power radios, fan motors and more.