Earlier this year I had the random alarm going off almost every night. A dealer update fixed it. Yesterday I pulled a trailer and everytime I locked the truck the alarm would go off within 15 seconds. Unplug the trailer harness and no issues. Ugh!

 

Yup! There's something wrong with the software load on the trailer anti theft.

There's the quick fix: disconnect the trailer.
Or there's bugging the dealer service department about it

 

My had the trailer disconnected alarm constantly when I had a trailer hooked up. There was an update done by dealer about 2 months ago. Don’t remember which update it was but I’ll post a pic of the two updates performed. My trailer has been hooked up all week and I haven’t had a single issue since the update.