I have 2015 F150 XLT with the extended cab. I have noticed a few times that while driving it the dash would say that the driver side rear door was ajar. Also I have noticed that when parked and not locked the lights would sometimes come on. And to top it off when it is locked the alarm would go off. Apparently when the truck thinks the door is ajar when it is locked the alarm will go off. I believe the door sensor is bad and needs replaced. It is a real treat to hear the alarm go off in the middle of the night every night!