John,
I'm stumped. The diagrams I have seen of this type of gauge show two coils in series...powered at one end and grounded at the other end. The sending unit is a tap between the two coils. The coils act as electromagnets on the little needle, swinging it one way or the other based on the variable ground..the sending unit.
If the gauge isn't grounded properly through its case, maybe the whole deal doesn't work.
I agree with you. Some gauge movement would indicate the gauge is good and another problem might exist. A 6 volt gauge that had been cooked with 12 volts would be dead..no movement.
I don't know how a positive ground gauge would work if connected backward. I would suspect it wouldn't work at all, but would not be destroyed.
This system passes such a tiny amount of current I think it would take a real hit to kill the gauge.
If the gauge truly did have a strap or something that looked like a ground, and it is broken, it wouldn't take much to repair it and see if that solved the problem. Good luck and keep us posted.
Stuart
