2011 Silverado LTZ here, 4 door with factory DVD. Cab lights don't come on when doors are open. The first thing that comes to mind: Light override switch-Nope, its in the correct position. The dimmer dial that turns on the cargo lamp and the interior lights, only turns on the cargo lamp and dims the instrument cluster and the navigation/radio. I can manually push the light lens and each light can be turned on/off individually, they are single filament bulbs, so they aren't getting power when doors are open. I've removed and inspected every fuse from both fuse panels, they look fine. Don't see any relay that would be responsible for that operation, though it really sounds like a relay issue. Removed the cover from the circuit breaker power center near the brake pedal, removed and tested all four circuit breakers for continuity, and they tested good. Stereo works as expected, stays on after key is removed until driver's door is opened, so it doesn't seem to be a door switch. It doesn't matter which door I open, lights don't come on. Is there a module or computer responsible for all theses "courtesy lights?" Could it be that the override switch has failed? Could there be a relay hidden someplace, maybe near the high mounted third brake light (since the cargo lamp works)? Help, I need somebody, help not just anybody. Someone else must have had this issue??????