This occurred today for the first time, startled me. Turned off truck and opened door for a few min but when re-starting sound persisted. Had no choice but to drive 30 min to dealership. When I arrived, I left the car on with the sound blaring and grabbed the manager. He heard it, a salesman heard it, but they shut the car off and left it there for about 10 min and when the car restarted, no more noise. I did record it and showed the tech but all he did was a master reset. I'm annoyed and unhappy that this has been happening for some time and there doesn't seem to be a fix? Really dangerous, luckily it occurred when I was pulling out of a parking spot, if I was doing highway speeds, could have been much worse.
My ears are ringing still.