a safety feature is built into front windshield shades, tying them to the ignition, in either the 'ON' position, or while running, to prevent the user from bringing the shade down too far and blocking the driver's view...
(the same feature controls the steps, the awnings, and the slides)
if your shade is not coming down all the way, even without the ignition on, then first run the shade all the way UP, then try it all the way down again.
If still no success, you may have to 'reprogram' your shade, if you have the type that has a 'button' hanging somewhere near the driver side end of the shade roller. This button allows you to tell the shade 'where' the fully down position is. You should have some instructions within your bag of product info/manuals.
two Campers, two Electric cars
former diesel pusher traveler