easy fix, if WD40 doesn't cure your problem, this should.REPLACE the sensor in the door mecanism.What the WD40 does is loosen the gunk and dirt build up in the door latch to where the sensors stem lies, First remove the door panel, second on my 2000 explorer there are 2 wires one is the ground and the other connects to the sensor disconnect both, third remove the screw that the ground connected to , Forth turn the sensor counter clockwise quarter turn is all it takes and remove there will be a stud in the sensor sometimes they get stuck it should push in and come back out if it doesn't, so just replace, if it is stuck in the sensor than thats your problem, reverse step 4 back to 1 , it solved my problem .