2012 Toyota Prius Owners Manual - Page 926

1-3. Opening, closing and locking the doors Alarm Situation The "POWER" switch was turned to ACCESSORY mode while the driver's door was open (or the driver's door was opened while the "POWER" switch was in ACCESSORY mode) Correction procedure Interior alarm pings continuously Close the driver's door, or turn the "POWER" switch off The driver's door is open with the shift position in R Close the driver's door, shift the shift position to P, or turn the "POWER" switch off