Though the license plate lights work when I open the trunk lid. I notice that they go out when the trunk lid is closed about 1/2 way and they don't work at all with the headlights on in either position. I looked for a plunger or some kind of switch that might be getting triggered by the trunk hinges but I don't see anything. Does anyone have any thoughts? Could it be something with the wiring harness? Many thanks.

 

That is usually a break in the wiring harness between the trunk and body of the car. Kind of typical.