I noticed this plug just hanging out in the wheel well of my truck. It must have been there since I bought it because I've never messed with it and everything works fine. I can't tell where the wire goes to, and I'm not seeing any receiving end for it to plug into.

 

I guess fog lights.

 

Yep, looks like fog lights.

When it came to trucks that didn't come with Fog Lights from the factory (mainly 4x2 trucks, 4x4 and Edge/Sport usually always had fog lights), most of these trucks were fully wired, some only had the connectors at the bumper but not at the radio bezel for the switch, and others had the connector by the radio bezel, but nothing at the bumper. There's no rhyme or reason for this that anybody has ever figured out.