I was helping a friend w/ trailer wiring on a 2001 S-10 and under the truck I found 3 connectors that are new to me. I know alot of newer vehicles w/ tow-prep packages come w/ connectors that are "capped" and all you have to do is buy the special factory pigtail and plug it in and end up w/ a 4-way or scotch-lock a 4-way to the wiring.

So, I was looking to see if it had a factory trailer wiring connector that I could use and found the 3 connectors. 2 of them were identical(about 6 wires) and were below each tail light and the third was larger(about 10-12 wires) and in the center behind the spare. The thing that is new to me is that when I took the caps off, instead of the caps just being plain plastic, they had metal pins in them that actually plugged into the connectors like jumpers. All 3 were just "dead-ended" connectors, but the caps have those metal pins. What are these?

Thanks in advance.