While driving a 2016 Ford F-150 XLT Supercab with a 6-speed transmission and 5.0L V-8, the truck was acting abnormally where the rear tires locked up and chirped once, then acted normally. The following week I auto-started the truck to warm the engine up prior to leaving for work, the transmission clunked into reverse and moved, then when in forward motion the transmission lagged and heavily shifted upon acceleration. I turned around, came home, and switched vehicles. Upon arriving home after work, I took the truck for a test drive and it functioned normally, so I continued onto the grocery store. While traveling at 35mph, the transmission slammed into first gear and jolted me. The transmission began shifting on its own from 1st to 3rd back to 1st then to reverse. I was stopped in the middle of the road. I shut the truck off and waited approximately 5 to 10 minutes and tried to restart the vehicle. It wouldn’t start, then it finally started and I pulled off to the side of the road. (There was no shoulder.) I gingerly pulled out and started my way back home. Luckily I made it home. There was no engine light (wrench) on the dashboard. I let the truck sit overnight. I started it the following morning, and then the light turned on. Now, if my family (wife and [XXX] ) would’ve been in the truck while pulling a trailer and 4-wheelers on our way out of state for the weekend and travelling at highway speeds (65-70 mph) and the transmission would’ve unexpectedly dropped into first gear, the truck and trailer would slam to a stop and there would be a pile up accident with death / mangling done to my family and myself. The truck was taken to a Ford dealer diagnosed with a [XXX] transmission wiring harness control being faulty, and replaced. I drove the truck for 2 months before travelling with a travel or allowing my [XXX] son anywhere near the truck. The repair fixed the issue, but we’re strongly considering selling it. Repair cost ~$1800 INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552