Brake Controller Wiring

[crawdad]

My 2012 Silverado came with the towing package with factory installed brake controller and 7 way plug mounted on the rear bumper.
Up until recently, I haven't had a need to tow anything with this truck. Now, with my old truck gone, I am needing to use this truck to tow some lumber on my equipment trailer but can't seem to get the trailer brakes to work.
I've doubled checked the wiring on the trailer and everything seems to be fine on it.
Today I was reading through my owners manual and, if I'm reading it correctly, the brake controller is not even wired up when it comes from the factory. It says it must be hooked up to the fuse box in the engine compartment by a dealer. That doesn't even make sense to me, but is that the way it is? Did any of you guys have to have your dealer hook it all up?

[crawdad]

Update: I've checked the wiring to the controller and it is connected to the fuse box. I'm getting trailer lights, but I'm not getting any power output at the connector. I've checked the fuses and they all appear ok.
Question, does there have to be a trailer connected to the truck in order for the controller to work?