eth555

To me the wire looks like a deadhead, or an unused wire; since there are various models of trucks and features, they use the same wiring harnesses in most of them; but not all wires are used. Might be worth a few $$ (I would guess $100 or less) to take to a Ford shop and have them diagnose, they are able to pull up the sensors to see what ones are working and which are not.

IceFishinFool

That is the sensor to read the temp. If you put it in between your fingers your temp reading will go up assuming it is cool outside and you hold it for long enough.

BCBob

It is an intentional deadhead. On my 2008 it's for the brake light on my canopy (or topper... or cap)

lariat05.4

Thanks for the replies guys. I'll just have to keep troubleshooting with the sensors.
Scobar- yea I put blue LEDs in the truck and wired them to a switch.