Its the multifunction switch...absolutely the worst quality piece on any Ford vehicle. I've had a little luck in the past removing the switch and cleaning it well with terminal cleaner, but others I've had to completely replace. They're easy to replace so don't let the dealership charge you $200 to do it. The switch is about $45 and it can be replaced in about 30 minutes time.
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Jeff Chambers
T/S #3
11.86 Seconds/113.8 MPH
Chambers Racing Team