Door Ajar 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.
When any door is ajar and the ignition switch is in the RUN position, the door ajar warning indicator is activated and remains on until all doors are closed. A one second warning tone sounds once any time the key is in the ignition switch and any door is opened.