Factory trailer light plug in question

[kris]

I have a 2006 Ranger Sport 2wd. It has a factory 4 terminal plug in just under the bumper. There is no voltage at this plug in. Is there an additional fuse that has to be added to power this plug. The fuse panel under the hood has left and right signal fuses but nothing else related to trailer lights that I can find.
The in cab fuse panel that is by the passenger foot well has 3 unmarked white switches. What would these control? The manual makes no mention of them.