Good advice. BTW Classic Industries lists an ammeter as 1970-75, a voltmeter as 76-78 that looks just like what I've got. Oddly though, I have a replacement dash panel stashed away, and I looked at that today. It has the same voltmeter! Gotta be from the 76-up cars. The car had this stuff when I got it 14 years ago, but I never had this problem until recently so it can't be a catastrophic mismatch. BTW the meter reads 8-18, not 0-18, so the left pin is a true 0. My bad.
I unplugged the hot lead from the meter and everything (even the dome light) still worked. So definitely not an ammeter on the same line as the dome light or anything else. Only God knows what my real wiring diagram is after 40 years
I'll keep pluggin'! Of course, everything is working fine now, even the dome light (I took it off the roof and it seemed to have good looking wiring... yanking on them had no effect on anything, good to bad or bad to good).
At least I'm pretty
sure I have an open circuit somewhere and not a short. Bad ground always a possibility I suppose.
PS nice Vicky!