You will get a horn beep when you push the key lock and something is open (i.e. door, trunk, frunk, console box), letting you know the car is not secured.
You will get a horn beep when you push the key lock and something is open (i.e. door, trunk, frunk, console box), letting you know the car is not secured.
You forgot to mention that it will also beep if the radio pressure switch is not properly grounded when replacing the head unit (this thread is a reminder that I need to find a better ground for that...)