Four Flat Wiring

So my tow connector has some messed up wires. I want to repair this but I’m not 100% sure what the red wire is supposed to tie in to. Help? Thanks.

 

Since you didn't show what color is attached to the green with already connected using the butt connector it hard to say? A test light would tell you, but I can GUESS that if the wire hidden by your thumb is green and all the rest of the wires are matched according to color I would guess they should be color matched. But that is a guess and a test light will tell if you are right or wrong.

 

The wire under my thumb doesn’t exist. That green wire with the butt connector is loose. It comes from the passenger light. It looks like most kits have some sort of black box that connects these wires. Maybe the previous owner bypassed that box. Idk. The wires are old and pretty stiff. There are a few cracks along the coatings. I may just replace the tow harness all together.