[72stepside327]

Anyone have experience wiring up the factory battery gauge in a 1972 C10? I recently did a swap out from idiot lights to factory gauges, now everything works but the batt gauge.

I can't understand how these old batt. gauges operate. They basically have two hot wire hookups, one from the positive battery (passenger fender junction) and one from the red hotwire off the back of the alternator, at dash clip wires 12 and 1, respectively. I've been told the gauge measures the difference in amperage between the two. However, two hotwires don't make a circuit...there is no ground, except dash clip wire #7, which is seperate. But if you hook the gauge between positive battery and ground, you smoke the gauge.

Is there supposed to be a resistor or jumper across the back of the gauge? Mine just has this piece of varnished-looking cardboard. Also, I get continuity across both posts in the back. Does that mean the gauge is shorted, or is that the way it's supposed to be? Looks like the gauge is nothing but some fine copper wire wound around a chunk of plastic, soldered to each back post.

Any help appreciated.Thanks.