Key-in-Ignition Warning Chime
WARNING: This page is about a different car, the 2007 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
The key-in-ignition warning chime sounds when the driver door is opened with the key in the ignition lock cylinder, and the ignition switch is in the OFF or ACC position. It continues to sound until the key is removed from the ignition lock cylinder, or the driver door is closed.