96 Windstar door chime

help! my 96 Windstar open door chime wont stop sounding off even if the doors are closed. sometimes, while on the road and i open the driver door and close it, it will stop for a while, but when it reaches a stop sign/light, the chime goes on again. I dont know where the door sensor would be for that van. I tried looking for a pin or a sensor, couldnt find any.. help!