I had a similar issue recently. Each time my doors would unlock, my tailgate would drop - a big pain in the back side. I was also having issues with my turn indicators in the cab going quickly, like a bulb was out but all signals worked. The dealer had it for 2 weeks before they found a loose connection somewhere in the truck which was causing a short. No issues since.

 

So, a little update to this. The original dealer spliced in the new harness and the tailgate was still dropping on its own. I say original dealer because my truck is now at a different dealer who quickly identified the switch on the tailgate was the problem. It’s been replaced and the tailgate is no longer dropping on its own. They were surprised the original dealer didn’t figure it out.

 

Could just get s camper shell then no matter how the truck derps it won't open the tailgate without opening the hatch on the shell.

 

if you have the keyfob with the tailgate button, you may accidentally hit that button and not even know it. it's happened to me....just saying. These keyfobs are sensitive, I barely even hit the emergency button and the horn goes off.....

 

It's good, though, that the first dealer found the wiring issue. You would have had a fixed tailgate for awhile, then some other issue would have cropped up.

Removal of the tailgate down warning is probably so creepers won't know when their quarry is escaping.