for the second time, i noticed that the tailgate on my 2016 F150 opened when i went over a speed bump. i am concerned about placing items in the back when on the highway. how do i "lock" the tail gate?

 

Lock your doors?

 

On my 2017 and 2019 the doors lock when I get up to 20 km/h about 12mph. That includes the tailgate. I don't know if the 2016 does that as well. Even if the tailgate is unlocked it shouldn't just open even going over a speed bump. Is it still under warranty? When your truck is stopped can you open it without pulling the handle? Maybe try hitting it with your hand and try it locked and unlocked.