Up and under the dash on the driver side you would have a blue wire coiled up. Check your 12 volt fuse panel and see if you have a dedicated fuse for a trailer. I have one, fuse, but still could not find that dang blue wire so I had to start from scratch.
Seems to me that the Motor Home mfg's. would leave that wire where you can find it and have it labeled. But I guess that is to much to ask.
However from what I understand, the blue wire is the standard to a trailer wire.
1997 Triple E Empress, Freightliner Chassis, CAT 3126 w/ 275 horse's.
MD 3600 Tranny, 2011 Ford Escape Hybrid w/Blue Ox tow bar and Roadmaster Base Plate.
Amsoil Synthetic Oil only for my baby.