license plate light

I assume your are talking about the courtesy light.turn dimmer switch backwards and see if courtesy light works. If it does then that is the way it's supposed to work.

this is about the light that lites up the LICENSE PLATE on the rear door passenger side

check body ground and ground for light at back

where is body ground i found black wire from light screwed on to big screw with other ground wires.

the ground for the license light is behind right rear wheel house inside van. do the taillights do the same thing? also check at left rear wheelhouse interior same area for ground there. then if those are ok check for a broken ground wire leading to lamp, maybe broken where door opens if you play with it the light may go on then you have found it. If taillights work ok license light should as well as they are all hooked together.