My brake lights and turn signals work .the strange part is that I just had a brake line go on my truck I replaced it but still the same no running lights when I turn the head lights on no camper tail ...
I bought a 7 pin adapter that has the 4 pin adapter for the TC side and it has 3 red lights on top that let me know it's working on the truck side. So now if I'm having light issues, I can see if it's on the truck side or the TC side. I put newer LED tail lights on my TC and just found out the passenger side wires were crossed!