..and just in front of the black plastic box (which, indeed, connects your 7 pin connector to your exterior lights, brake lights, brakes, etc) is a plastic cover. Under that plastic cover is a humongous fuse. This is an in-line fuse in your
12V positive circuit. One end is connected directly to your battery, the other end goes to your
12V panel. I suspect most people don’t know that fuse is in there, but if you ever had a major short in your
12V circuit that’s a fuse worth checking.