Help with Tow Package

Hey guys, quick question. Theres an unused plug down below my truck near the tailgate, closer to the driver side. Black plug, I want to say it has 4 pins.

If you have the tow package installed, could someone snap me a picture of where the harness goes from the trailer plug socket.

Thanks in advance guys/girls!

 

There is a dual socket installed on the tow package bumpers next to the license plate, one of which is a 4 pin the other is a 7 pin. I'll try to find a pic of mine hold on.

 

This is mine

 

Is there any way you could see where the other end is plugged in? What I'm talking about is under the bumper on driver side, thanks!

 

It's directly under the rear bumper in the middle

 

The main reason I ask is because I have an SR 5 speed and theres an unused plug back there and I'm thinking its for the trailer lights but I didn't get a chance to bust out the multimeter