I have 98 Deville Concours and am havin an interior electrical problem. My dome, map, and mirror lamps do not work... also, ALL my cig. plugs do not have power. Ive checked all fuses and relays. Everything checks out. Any ideas? Thanks!

Did you check the fuses behind the rear seat carpet in the trunk?

Yes I check ALL fuses... BUT... I Had failed to check 1 relay... The "Inadvertent Power Relay" ... Turns out the wires were corroded. One of the wires had broke off. I re-striped the wires and re-attached them... Everything works fine now. Thanks