The contact owns a 2015 Ford F-150. The contact stated that while driving 60 MPH on several occasions with or without the cruise control feature activated, the transmission unexpectedly downshifted to first gear, and the rear wheels locked up. The vehicle was taken to an independent mechanic, where it was diagnosed and determined that the transmission circuit board and valve body assembly needed to be replaced. The vehicle was repaired. The manufacturer was notified of the failure. The failure mileage was approximately 105,000.