I disconnected the plug just as you said to no avail. The lights still repeated the issue. I found a hard plastic-type harness with lots of electrical tape around it and several exposed wires, but none of them seemed damaged. Here is a picture of that
harness. It is located just above the driver's side rear strut.
I did notice a wire that was sticking out of the harness. It's probably not the source of my problem, but I am curious as to where it should go. It has a label sticking off of it that says "CHMSL". In the picture below, that harness at the bottom leads to the trailer light connector.