The contact owns a 2018 Ford F-150. The contact stated that while driving at various speeds, the transmission was slipping. Additionally, while driving in high gear, the transmission unexpectedly downshifted to a lower gear. The vehicle was taken to a local dealer where the vehicle was diagnosed, and the contact was advised that the transmission lead frame was faulty and needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure. The approximate failure mileage was 59,000.