I think, that´s the fuse, but I´m not sure. Check the fuse (inner of the kick panel, left side.
Defroster switch won´t work? What about the yellow control light within the defroster switch? Make an selfcheck. Check the inner grids of power (12V) with an check lamp. If this not works, than it could be, that the switch is defect.
Question: Which function have the courtesy lights switch?
We here in German have instead of courtesy lights,...
an headlamp cleaner and cruise control main switch.
Mike / Cologne