I have a 2011 F150 and have installed the additional fuse and relay that came in the glove box. The outside trailer lights work fine, but the interior lights on my CM Charger 2 horse trailer only come on when the truck is running. Trailer dealer says inside lights should work as long as it's plugged into the truck. Not sure what is going on here or if I need to have some wiring changed in the 7-pin connector. I can't go back to trailer dealer as they are several 100 miles from where I live. Any suggestions are appreciated.
Thanks.

 

The lights in your trailer are apparently off the relay controlled "charge" circuit. They will only work when the truck is running. That is why the charge circuit has a relay, to prevent a dead battery.

 

You have 2 choices:
Add a battery to the trailer to power the lights or:
Bypass the under-hood relay to wire the charge line as always hot (like a GM.)
Yes, with Fords the charge line is hot only with the engine running. The dealer is wrong.

 

Don't feel to bad, the id10t that wired my horse trailer connected the interior and exterior flood lights to the running lights. I have to have my truck lights on for any of them to work. I have to get around to fixing that.