Power Door Locks - BUICK & CADILLAC Automatic: Operation: Buick
With all doors closed and courtesy lights off, doors are automatically locked when transmission is shifted out of "PARK". Also, unlocking the drivers door using the key, will unlock all doors.
On all models, if transmission is in "Drive" and any passenger door lock is manually unlocked, or unlocked using the drivers remote control switches, all doors will automatically re-lock when passengers door is closed.