Garage door power wire/camera install

[X5chemist]

Which wire should have power? I assume the larger one. I grounded the power adapter to an overhead console screw. I don't think it's grounding properly. I'll probably remove the entire console and ground to a metal screw. There was no place use my voltmeter leads. The leads were too short to reach any metal. I didn't realize how much trim covered all the metal. Anyway, the forward camera is installed. The wiring goes through the headliner into the console. A small end wire pin or electric clamp will be used for connecting power.