Child Safety switch.
The access to it on mine has been taped over.
Quote:
shaun eddy Aug 30, 2011
The pill-shaped hole in the lower right-hand corner of the door latch mechanism is your child safety lock. Note that this not located on the jamb side of the door, but on the interior side of the door jamb, i.e the side facing the interior of the vehicle. There should be a decal just under the hole. To engage the mechanism, insert your car key and slide up. To disengage, slide down. Try cycling this a few times to see if something wiggles free. Make sure you end up in the down position. Have a good one!