Check the other tires. If you rotated them, the sensor will still read for that corner, but the rim/sensor could be at a different corner of the truck.
Check owner's manual on how to reset them. Has something to do with turning on/off parking lights so many times til the horn blows, then starting at the drivers side front, releasing 10psi from the tire, after the horn blows go to the passenger side front. Do the same thing, continue to the rear passenger side, and so on and so on.