another bad amp guage

[Badpuppy]

Originally Posted by bobmc

... with the gauge removed from the car in my hand not wires attached it is in the -10 position

That tells you right there the meter is bad. Since this thread piqued my dead cat, I pulled apart my extra one and had a look. Appears to be the repulsion type, with two magnets. There's the obvious toroid magnet attached to the needle, and apparently a thin bar magnet clipped to the underside of the conducting brass plate. The opposing fields keep the needle centered. An iron or ferrite magnet will stay that way unless a strong field demagnetizes it. A dome lamp doesn't carry much current, not a strong field around its wire. But the ignition wire puts out lots of RFI - that would be the main suspect, I would guess.

I've got a strong magnet around someplace. I'll stick it behind the ammeter (has a bent needle now anyway) play around with it and see if I can duplicate the phenomenon. Seems odd no one else has had this problem.