What is this thing? I have a 2013 F150 XL and this is dangling behind the dash, just about right behind the headlight switch. If I take the access panel of the left-end of the dash (the panel seen when the door is open), this is there. The wires were looped up and taped to this device with gray electrical tape and there is a gray plug which is connected to a socket mounted facing the driver. The other side of this device goes to two wires which are butt-connected to wherever it goes. Does anyone have any idea of what this is for? This is a factory item. I did not add it and I bought the truck new with 7 miles on it. Oh, one of the wires is pulled out of the butt-splice and I've seen no alarms, faults, etc. and have not noticed anything not working.
I wish I could justify paying the outrageous cost for electrical drawings.. but I don't see the point of it now... not with 220,000 miles. I noticed this because I was in the process of adding a new 12V socket in the panel between the headlight switch and the parking brake release.

 

What's the service history on your truck? Any recalls or other work performed? Any aftermarket alarms, keyless entry, or stereos? Any custom headlights, taillights, or turn signals? LED lights?

Nothing about it looks like anything I've ever seen on a car from the factory. Post pics of the connector and butt-splices!

 

Socket? What's that like?

I paid $20 for my service manual.

 

Post up some pictures of the socket and splices as suggested. Best bet would be to find where those wires go to from each end of it. I'm wondering why it's got heat shrink on it when it's not even done right. You could cut that heat shrink off and see if there is a label or part number on it that you could google. Assuming since you bought it brand new I wouldn't think it would be any type of GPS or "kill switch" like what the buy here pay here lots install. To me it looks like a LED resistor.