Originally Posted by Brock250

I had this exact same problem with our 2007 4.8i.
It was due to the sunroof drains being plugged, and water dripping directly in to the passenger footwell fuse area. I used contact cleaner and rubbing alcohol to clean the relay inputs on the panel, and replaced my relay. That fixed it.

Sure is awkward when your rear wiper won't stop even when the car is off.