Trailer Harness Question

Does anyone know where the Aux Power/Dome wire (black wire in trailer cable, Pin # 4) in a 7 way harness originates from in a '14 Suburban. I lost the interior lights in the trailer and suspect I blew a fuse but can't seem to find an open fuse or anything on the fuse list that mentions Trailer Aux power. It is a factory installed trailer plug and I have confirmed I have good wiring from the battery box on the trailer to the switch but no juice. It has to be something dumb. That and how do we search for topics now, I'm sure this has been brought up before.

In our '12 Tahoe, I recall having to connect a stowed red wire up at the fuse/relay panel before I got power at the factory installed trailer plug.

Dunno if that's any help, but it's all I've got...

My silverado was the same way, but it was an orange wire. It was intended to be connected to one of the "aux" fuses in the engine bay fuse box. 2 fuses, each 30 amps. Not sure of your newer truck has any aux fuses, but might be worth looking for.

This is something that is/was connected. The lights have worked for years. The stakon connectors on the switch inside the trailer had broken off and when I found them, I hoped the hot wire had touched the metal framework and shorted out a fuse. After checking continuity of everything, the only thing I could find that was wrong is no power at the #4 pin on the truck. I thought I would find a blown fuse but no such luck. Will try looking for an aux  fuse and if no luck look to see if I can find an FSM wiring diagram. I was surprised that I couldn't find an answer from Google.

In reply to gearheadE30 :

Ding, ding, ding, you are the winner. The wiring is connected to a couple of posts that hang off the front of the fuse box, one of the posts had a 40A fuse that was open. I have lights inside the trailer again!