Problem with reverse lights and interior lights [Expired Topic]

I just bought an 03 K1500 LT with 75000 mi.
I bought it during the day, and didn't notice till last night that the overhead interior lights do not work. This applies to the 3 sets that are over each seeting row and also the lights on the inside panels of both rear doors.
I pushed the dome overide switch several times, and no change. I also tried manually turning lights on with dimmer dial by turning full up.
I also noticed the underhood light, does not come on, and the reverse lights are not working.
I checked the underhood fuse labeled INTPARK and appears fine, (I will double check with an Ohm meter)
Is there a relay or another fuse that might be the culprit. Perhaps one related to the Retained Accessory Power circuit. I know it is involved with all but the reverse lights.
Just FYI, the front row map reading lights do work, as well as glovebox light, and front door panel lights.
Any one with similar issues or a fix would be greatly appreciated.