Its easy but that little box is high for my jeep so i bought the cheapest one and spliced it in so it would work with my jeep.Im poor like that lol.Just trace the wires on your truck side from the four way and youll find it.If it looks melted or has the odor of burnt plastic replace it.
Yep if one of those are bad youll have to replace it since its sealed.If its bad and its shorting it will cause haywire,The little box im talking about is where the short should stop so it wont burn up your tow vehicle electronics.Forgot the name but if you cant find out ill find out,let me know.