Edit: SOLVED: My issue was the GM3. Replaced it with one I got at a junkyard of the same year (2003). The interior lights now work properly again.

I need help diagnosing my issue and following this wiring diagram. What am I looking for and where to test?

Problem: Front overhead dome light does not work. No interior courtesy lights work. I was able to short (not sure which wires now) inside the dome light and all the interior lights and dome light illuminated. Figured I had a bad switch. Replace the dome light fixture and still have the problem.

Not Working: Front Dome Light, all courtesy lights.

Works: Front map reading lights, front amber led ambiance lights, rear dome lights, rear map lights.

Door contacts: I "assume" the door contacts work because (1) if a door is open, the central locking does not lock the doors but does when all doors are closed, (2) if I open a door while driving the dash displays "door open."