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2005 F-Series Speedometer Needle Bounce, Cruise Control Drop Out, DTC P0500, and/or Uncommanded Wiper Activation:
If any of the above conditions are present, inspect the wiring harness running behind the coolant bottle to the wiper motor for chafing on a brake line clip and shorting to ground. If harness damage is found, repair and insulate the damage, and secure the harness away from the clip. Broadcast Message 3695.
I went out to my truck to see if I could find the relay for the wipers, I couldn't even find the wiper motor! Time to hang it up, things are getting too complicated
Before reading KW5413's post, I disconnected the ground to the motor and the wipers finally stopped (and yes, I did get my finger caught in the control arms between the wipers as I was messing around with the wipers on; ouch). I then disconnected the harness on the motor, then reassembled everything. They are now operating fine. We've had a couple of days of rain in NC over the past week, and all functionality worked. I'm going to find the harness that KW5413 identified to see if there is damage. -- Signed, Homer Simpson.
I'm glad you posted back on this one. It had me curious enough that I was going to start ripping apart my own truck to see what the potential problems could be. If it turns out KW was right, don't tell him. It'll just go to his head and you know he'll be impossible to live with after that.