Mike, this is the same trailer I have. See if the black and white wires at the wheels are enclosed in a gray jacket. This gray jacketed wire (if factory) should run into the belly pan and then to the unbilical connection under the front gaucho/sofa. In my camper it is connected to the (I think) yellow wire at the umbilical as well as a 12v
dc power wire. I'm doing this from memory. If you can wait until tonight, I've got lots of pictures of the set up in mine (which is factory original).
Kevin's link above should show how it looked coming out of the factory, unless lots of stuff inside
the trailer were rewired.
Also, a look at this thread may help: