The micro-switch sits upside down just below the actual locking latch itself. It activates by riding on a cam that rotates with the locking latch. When the latch opens (door open) the micro-switch is activated and the window stays down. When it malfunctions the problem is more than likely because of wear. The cam and switch have lithium grease on them for lubrication, but after time and dirt getting into the latch it will wear. I pulled my switch out and was able to trim off some plastic on a couple of tabs that aligns it on the cam and with the spring that holds it down was able to get it to work again.
This can only be done with it removed from the door. If yours is malfunctioning and before you replace or try and fix it, try spraying some penetrating oil into the bottom of the latch assembly into the door. It might be enough to get it to work, if not you'll have to remove it anyway.