1973 Plymouth Duster repair and rebuild

WTF, where do I find a diagram of the headlight switch and identify what each wire is for? The wiring diagrams for my car at MyMopar is useless in providing this information.

I though I had bought a bad headlight switch, so I exchanged it for another. Even changing brands from cheap to Napa. Still nothing. I found what I thought was the 12v source coming into the switch. Can anyone tell me if there are 2 terminals on the headlight switch which have 12v coming in? If not, then its safe to assume that I found the source terminal. And when I jump to the terminal going to the tail lights, I have an appropriate light. Hit the brakes, and those come on.