Ignition Key Reminder Tone Alarm Function
WARNING: This page is about a different car, the 2004 Mitsubishi Galant. However, it is still accessible from the selected car via links, so may be relevant.
When the driver's door is opened with the ignition key inserted in the ignition key cylinder (ignition switch is in the OFF position,) the tone alarm sounds intermittently to indicate that the ignition key has not been removed.