99 RX300 bell going off

[Rodsrx]

Have 250k on it with new battery and alternator. For some reason now when I'm driving there is a bell tone that goes off about every minute. And just one chime at a time. When parked it doesn't. Appreciate any help. 

Thnx Rod

[RX400h]

Perhaps it is related to the seatbelt connection or door that is not fully closed, although I would think that either of these would result in an illuminated symbol. I would check the seat belt and door switch.