[ERY]

Fixed it. 2018 EX-L
It’s two beepers. One in the driver’s side rear panel and the other under the bumper skin right in the middle.
For the bumper one I removed the 5 mm hex bolt under the left tail light, pulled the bumper skin back and put tape over the beeper. Everything there went back pretty easy, it took a little fiddling to get the weatherstrip back exactly right because I didn’t pay attention to what it look like before.
For the side rear panel I pop the cover off the netting clip, remove the 8 mm bolt and simply peel the panel back. There’s a black box there with three plugs in it. It’s held in place with one Phillips head screw on the top and a flat piece of metal that it just slides on to in the bottom of it. I opened it up and put a piece of tape over the beeper.
All is quiet. View attachment 133140 View attachment 133141 View attachment 133142 View attachment 133143

Fixed it. 2018 EX-L
It’s two beepers. One in the driver’s side rear panel and the other under the bumper skin right in the middle.
For the bumper one I removed the 5 mm hex bolt under the left tail light, pulled the bumper skin back and put tape over the beeper. Everything there went back pretty easy, it took a little fiddling to get the weatherstrip back exactly right because I didn’t pay attention to what it look like before.
For the side rear panel I pop the cover off the netting clip, remove the 8 mm bolt and simply peel the panel back. There’s a black box there with three plugs in it. It’s held in place with one Phillips head screw on the top and a flat piece of metal that it just slides on to in the bottom of it. I opened it up and put a piece of tape over the beeper.
All is quiet. View attachment 133140 View attachment 133141 View attachment 133142 View attachment 133143

This is very helpful for a permanent solution, thank-you. I found I could just turn the latch mechanism in the tailgate to the closed and locked position. Beeping stopped. When I’m done driving with tailgate open I found I had to have car turned off, “open” (or release) the tailgate by using the key fob, and then when the lock releases/clicks, I have to manually put it back into the open position so it can be closed properly again.

I have also used this as an anchor point to tie the tailgate partway closed when I have a load in the back.