Buzzer Sound Function
WARNING: This page is about a different car, the 2003 Lexus IS 300 and 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.
If all doors indicated that they are locked after the lock command, the keyless buzzer goes on once. If any door indicates that it is open after the unlock command, the keyless buzzer goes on twice. If luggage door indicates that it is open after the open command, the keyless buzzer goes on once.
When the body ECU receives the lock signal from the wireless door lock control receiver while any door is open, the keyless buzzer goes on approximately 10 seconds.