If you are installing the USB port in your glovebox, there is a + and - on the back of the plug. I didn't notice and had my wires backwards, wouldn't work. Double checked and that was the problem.
You need to add the harness that comes with the kit .It plugs/splits where the visor power comes from .Where is the connection plug located? Once you remove glovebox lid and top shroud is it right there?