l live in texas - meaning usually dry and never icy.l have mentioned it to a couple of folks and they look at me like l am crazy.However, my 5 yr old heard it one day AND now a friend has too.Any imput is appreciated.
l always use the seatbelt and my son is alway in his carseat in the back.l have not noticed whether l have bags or something heavy in the front seat. l will look into the BCM re-flashing???Thanks.

have your BCM (body control module) or the ECU tested. chances are it needs to be reflashed.

Are you using your seat belts? that may be the noise.

If your daughter weighs less then 85 lb is the seatbelt alarm will go off when she is sitting as she if under that weight should be in car seat in back by law. It is a Toyota safety feature if it is these conditions.