Strange Voltmeter Issue
My '72 Camaro runs great, but in the past year I've had an intermittent problem that is driving me nuts. At times, the voltmeter pegs itself to the left, past 0 volts. When this happens the dome light fails to operate. Everything else seems to work. The battery terminals read over 13 volts (meaning it's charging), the exterior lights, dash lighting, heater, other gauges etc. all seem fine.
I had replaced the alternator and jumped out the old voltage regulator months ago, but it has failed to address the problem. I obviously have a faulty connection someplace. But what circuit do I home in on? Everything under the dash seems ok visually. What common circuit would my voltmeter and dome light occupy when everything else works?
It's hard to trace because even if I disassemble the dash (as it is now) the problem will disappear and then reappear. No wire tugging (so far) seems to have an effect.