I don't have anything extra plugged into the truck when the camper is plugged in. Just the camper plug. I thought maybe the brake controller but it is always in the truck and I didn't tap onto the output wire for the brake controller.
I checked the voltage on the lance plug and I have 13v on the charging wire that is coming from the camper battery and isolator. but on the truck side, that wire is just capped off under the truck.
Can it be anything with the 8 gauge ground wire that I have bolted to the truck chassis but I don't have the 8 gauge hot wire to the batteries? I was just figuring the ground needed to be hooked up in order to make the turn signals and brake lights to work.