Quote:
Originally Posted by TA1754
I've got the entire gauge cluster out of my '58 chevy stepside & just installed a new fuel gauge.
When I removed the 2 wires on back of the amp gauge, they weren't marked.
I connected power back to the battery, checked each wire, & both have constant 12 v. to ground.
I called the shop that rebuilt my speedometer couple yrs ago, he told me only one should be constant hot, 2nd wire should be load going to lights etc.
Running a 77 350 engine, & complete drive train is from a 77 malibu.
Can't recall ever seeing the gauge needle reading wrong when it was hooked up.
Need some advise.
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Both wires are positive since it measures the amperage going through the positive side of the circuit. You are reading the normal voltage potential between positive and ground, and stating that they are constant hot to ground sounds like they are shorted to ground, which is not what you meant.
Prior to 1963 all the positive current ran through the Amp meter which only read up to 60 amps. GM decided to go to a battery gauge which only measures a tiny current that shows whether the alternator is charging or not.
It also reduces the fire hazard from a short with this type meter, since it is fused only with a fusible link at the battery.
This is your wiring diagram and not knowing which wire goes to which side of the ampmeter only means that the meter will read backwards showing negative amperage (discharge) when it is really charging. You may be able to read the diagram and figure out which of your wires goes where.
You probably have a generator instead of an alternator as shown in the diagram but the general wiring is the same.