Fallon
Super Member
Trailer Wiring Diagrams | etrailer.comthere are so many different wiring diagrams and trailer connectors, between round pin and flat, 6 or 7 .
if you goggle trailer connector pin outs you can find all the different ones and the color codes.
Of course that assumes things are properly wired with standard color codes. Trailers are often wired with non-standard colors, especially older ones. Not sure if truck manufacturers color code the OEM plug wiring or not.
The gold standard is always testing it yourself. Either with a multimeter, test light or fancy $10-20 plug tester (which is just a handful of test lights on a plug). The Etrailer page lists out what pins do what if you scroll down.