Tesla Full Self Driving (FSD) failed us, resulting in a side swipe with a tractor trailer and the likely total loss of our Model 3. We were under FSD for much of our trip from [XXX] to [XXX]. We were in [XXX], traveling north on [XXX] in the right lane with a tractor trailer in the center lane. The car made a sudden, violent turn to the right. The startled driver grabbed the wheel to bring the car back to the lane center, which resulted in a major grinding noise. The driver then brought the car to a safe stop on the shoulder. It became clear the left side of our vehicle had contacted the trucks right front wheel. The truck left the scene. I believe the truck either came close to its lane right line or actually was changing lanes. The car took evasive action. However, the car failed to communicate the situation to the driver, which is the reason for filing this report. It is possible that had FSD activated the horn, both driers would have acted more appropriately and the loss of our car might have been avoided. Other possibilities are for FSD to have some method to communicate what was happening or had refused to permit the driver to bring the car into contact with the truck. It may be beneficial for NHTSA to request a copy of the car’s data before it is deleted after the car is declared a total loss; especially since there isn’t any Dash Cam video of the incident. The dash cam’s most recent video was several weeks previous and includes GB of video taken in our garage. But