wipers stay on all the time even with key out of truck

 

Does the vehicle only do it when you leave the truck's windshield wipers on or even if you turn them to off and turn the truck off? Usually there is a solinoid some where between the wiper motor and the switch. I had a bit diffrent of a problem with my 1988 F150 the windshield wipers would never come on at all so I replaced the motor and that didn't work and looked for a solonoid and sure enough there was one on there I replaced it and it worked again. But a 2002 may be diffrent not sure I haven't had our 2002 F250 very long to know everything about it.
Trav