brake switch on a 65 c10

[spookylynx]

So I am starting the wiring on my 65 c10. Using a Speedway universal GM harness.

I was going to wire the brake switch, there are two terminals on the back. I imagine one is for the switch wire and the other is a ground, but they are not marked. Or, the markings have worn off. The original harness has been out for a while so I don't have a reference.

How to I proceed or test to see what goes where.

Any guidance is appreciated as like a lot of people wiring is not my strong point.

Thanks

[_Ogre]

one wire is 12v+ keyed hot, the other wire feeds 12v+ to the turn signal switch
no ground, that would be a dead short

there is a sticky at the top of the electrical section with full 60-66 wiring diagrams