No running lights on trailer

I picked up my 2012 Armada last night, today I took it to a BIG RV dealer where I bought 2 trailers in the past, to hook up the brake controller, No running light on the trailer, everything on the Armada works. Took it back to Nissan they said the guy at the trailer has to use the Nissan wire harness with the controller or it won't work, took it back to trailer dealer, they said the only difference between their harness and Nissan's is the Nissan one has to be spliced and the one they used is plug and play. They unplugged the controller unit and still no power to the running light part of the trailer plug.The trailer dealer said there is no power at the plug under the dash for the running lights before the connector, I'm hoping it's just a fuse maybe. It's under warranty of course but I hate stuff like this. Took it back to Nissan and I have an appt next Tuesday so they can check out the thing. Any ideas of something I can check myself??
signal lights and brake lights work on the trailer, just no running lights.