No headlights on '75 duster

grades said

Here's what i did today, i plugged the red (+) wire of my voltmeter to the + terminal of the battery, and the negative into the headlight plug which showed my 12 volts on 2 of the wires. I guess high and low beam. So that means that the ground is ok right?
This was with the headlight switch off.

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You need to learn basic multimeter use (youtube, etc).

Normal use in voltage mode is to connect the black lead (-) to BATT- and the red lead (+) to whatever you want to know the voltage of (rel. to gnd).

The other basic is measuring resistance between 2 points. In your case, check gnd by measuring ohms from the headlight plug gnd terminal to BATT-. Should be <5 ohm.

Not sure what to make of the dV measurement you made. With the switch off, 2 of the 3 wires are floating.

Not sure why you are guessing which wires are low and high beam. The wiring diagram has a pictoral view of the headlamp connector and gives the color code.