Back up and dome light on 2005 Chevrolet Silverado 2500 HD

My back up and dome lights do not work. The bulbs are good. How can I trace the wiring? Or, should it go to the dealer?

The fuse panel next to the door has three 15amp fuse at the bottom right one is burnt out. I found it on mine . hope this helps
Thanks that was my problem dome light and b/u lights have been off for couple years..
that was my problem also thanks, i even replace the switch and still no luke
1 more answer
You will need a wiring diagram, a voltmeter, and the ability to interpret the diagram and diagnose the circuit. If this is over your head, you should consider taking it to a shop. Try our directory if you don't know where to take it: