I been towing my 17ft Safari Condo “Alto” F1743 trailer for 5 months now. When hitched and the electrical cable connected so that the blue tow icon shows in the drivers display, when backing up the X ultrasonics audible alarm sounds. Of course they are detecting the trailer; I can see that shown in the driver’s display. But the firmware should mute the alarms since it detects that the car is hitched because the trailer electrical cable is connected to plug next to the Bosal hitch. I am interested in hearing from other X owners who tow to see if their rear ultrasonic alarms go off when they back up. So far I have heard from two X owners I know who tell me their alarms do not go off in that situation, which is the way things should work. But not with my car. I spoke with my local Tesla Service Center about this issue several months ago. They asked me for the approximate date/times when the rear ultrasonic alarms went off while hitched and backing up. I provided that information, and a few days later got a call saying that it appeared there was a firmware problem with my car and when they had a fix they would push it to my car. I have had at least two firmware updates since then but the problem remains. Note: installed a Tekonsha P3 brake controller before I picked up my trailer following the excellent instructions in another thread here, it appears to work fine and I don’t see how it could be related to the problem I describe in this post.