Re: courtesy lights
The power supplying your switch is terminated at the center terminal. The power that feeds your lights comes off the bottom terminal. Check for power first at the center terminal. If you don't have power there, check the fuse that protects that circuit, unless there is a breaker that protects it, make sure it's not tripped. If the fuse/breaker check OK, then turn the switch on and see if you have power to the bottom terminal. If you do, then it is the wiring that goes from the switch to the lights. If you don't, then it's the switch.