Panic Alarm
WARNING: This page is about a different car, the 2007 Pontiac Solstice. However, it is still accessible from the selected car via links, so may be relevant.
The horn will sound 3 times and the headlamps and parking lamps will flash 3 times. Press and hold the button for 3 seconds to sound the panic alarm. The horn will sound and the headlamps and parking lamps will flash for 30 seconds. Press the button again to cancel the panic alarm.