From autogenius.info, on a 2003 Deville:
=== ***Underhood Fuse Block*** ===
The underhood fuse block is located in the front of the engine compartment between the windshield washer fluid reservoir and the power steering fluid reservoir on the passenger’s side of the vehicle
[image|2621530]
=== ***Minifuses*** ===
Fuse Usage[br]
23 Cigar Lighter
=== ***Rear Underseat Fuse Block*** ===
To access the fuses, push in the two tabs located at each end of the fuse block cover.
[image|2621534]
=== ***Mini Relays*** ===
Relay Usage[br]
58 Cigarette Lighter
=== ***MaxiFuses*** ===
Fuse Usage[br]
65 Cigar Lighter
So there are two fuses and a mini relay that control power to the cigarette lighters and you'll need to check them all.