an electrical nightmare , please help , 1972 dart

67Dart273 said
IT MAY BE that the lamps are not GROUNDING, which would feed "evident" power back on the unused line. The way to find out is to turn on the lamps and measure at all three lamp terminals. Only one lamp terminal should be hot at one time. Unplug both lamps and see if the "3rd wire" goes cold

I finally got to the lamps and sockets . With lamps loose , but attached , all three terminals on both headlights had power at the same time . They all lit up with the test light . After unplugging both lamps , the "3rd wire" at the dimmer switch went cold . With both lamps unplugged and headlight switch on , I was seeing 6 to 12.30 volts at the top terminal of the headlight socket . 0.20 - 0.30 on one of the side terminals and 0.00 - 0.03 on the third . It was about the same for both sockets .

67Dart273 said
What have you done to check grounding and do you understand how?

i do not know how to check grounding . all i have done is cleaned up the ground where the wires connect at the radiator/support . just to bare metal as best as i could . Same for the negative battery cable end at the block .