F350 Wipers won't turn off
 

My 2006 F350 6.0 has wipers that will not turn off. At start up, they are not on. Once I turn them on, either in continuous mode or intermittent, they run at normal speed only. They will not go intermittently or high speed, and they also won't turn off. I have to go under the hood and pull the fuse to stop them. Any thoughts before I start buying parts?

Always a good move to check the grounds at the wiper motor and mtg.