I have a 2005 Express 2500 and the dome lights stopped working I didn't find any info when I searched the threads.I'm thinking its the panel behind the switch but not sure, Thanks Jim

 

not 100% sure on the dome light setup in the 05, i got an 01 with just a basic light but have you popped it off an checked if you are getting 12v across the terminals?

 

On the 05 the dome lights share a circuit board with the headlights so they turn off automatically etc. the headlights work fine,now I've noticed the backup lights don't work I don't know if they share the same circuit as well