If you have a light beside your hitch, like the NorthPoint does, take it off and pull the wires out from the 7-way plug. That’s where they terminate.
The yellow wire is the reverse light wire, I would assume it’s not hooked to anything.
Here’s my back up light mod
https://www.jaycoowners.com/forums/f...res-33346.html
It’s on a Nothpoint and our layouts are different, but I could find no way of feeding a wire across the overhang to get to that hole with the wires. Maybe you can get an idea from what I did