take the sliding door and open, the metal pins (7) of them come out of the door. take a small screw driver and pry open the plastic holder these pins come through. once you get it out about 1/4 in you can push it back in and pull out the two black plastic put in securing bolts (not really bolts, more like plastic anchors).
put the plastic unit out. look at the assy close, take it appart and clean the grease and crud off the pins and notice the springs come out as well as the pins.
the problem is the contacts that grasp the pins conduct current for the signal and need to be stressed with the pin out so that when you put it back together it is tight to the pins.
try that and clean the pads on the door post but make sure you don't contact more than one at as they may pass current between each other if you use a conductive cleaner like a emory cloth.
don't shine too much on the 7 pads.