Driving home from Colorado I heard a slight "ringing" sound that varied in loudness. Checked the doors, windows, tailgate, etc. It stopped and started a few seconds later, even with the ignition off. It went off and while driving through Texas I heard a slight "ring" or "whistle" each time I hit the brakes when the vehicle took a nose dive. I heard it a few times when the vehicle leaned to the left on a hard right turn. Have been home several days and have not heard it again. No lights came on and no fluid leaks under the car (2010, 4 Runner Trail). What kind of alarm would go off when the ignition is turned off? It was more like a "ringing" alarm, not a "dinging" alarm like a door adjar. Anyone have a suggestion?