Where is the sensor in the driver side door of my 98 windstar?

Lately, the open door chime continues even after the door shuts, and the interior lights stay illuminated after exiting the vehicle. I've had to disconnect the battery when this happens and now I don't use the drivers side door at all now. The door is closing securely, but the van doesn't seem to notice. This has happened on other vehicles I've owned, but the answer has usually been a sticking on or something. Ive checked all around the frame of the door, both on the body and the door itself, but see nothing I have identified as a sensor-type mechanism. Help!