When it rains. Tailgate opens on it own. Either have to lock truck or quickly put into drive to prevent tailgate from opening on its own. Only in wet weather. Tailgate opened on its own in rainy weather when parked at hardware store. I began to drive away not knowing tailgate opened and lost tool box and material out the back while making a turn. Speaking with GM I was explained its a known issue on 2500 models but not for 1500 models.