Bought a 2006 F350 a few months back. Have most of the kinks now straightened out and one puzzles me. Sometimes the wiper speed is correct in that on the highest speed the blades move at an appropriate speed. At other times, on the highest setting, pretty slow. I am not sure changing the wiper blade motor is the answer. What should I be looking to do to fix this issue? TIA! wg

 

Check your grounding, and wiring connections for the wipers. I had wipers that barely moved, motor didn't fix. it ended up being the alternator starting to go out. Sometime the alt would output properly, then it wouldn't.