If it detects that the occupant seat belt is unfastened, the warning light or beep alerts the occupant.
Refer to Taking Action (Search).
Refer to Seat Belt Warning Beep (Search).
Seat belt indicator light (rear seat) (green) (Some Models)
The light turns on when the ignition is switched ON and a rear seat belt is fastened, and then it turns off after about 30 seconds.