The cigar lighter and aux power outlet are a different problem. For them did you check the 20 Amp fuse in underhood electrical center to see if it is blown? I think it is fuse #34 but it is the only 20 Amp fuse in any case.
In regards to you complaint on what I would call your instrument cluster backlighting, does other backlighting in the vehicle also not work?
Trunk Release Switch
Panel Dimmer Switch
Heater A/C controls
Door Lock Switch
Power Window Switch
Shifter Gear Indication
This would help determine if this is a problem with just the instrument cluster or something else. It is good that you confirmed that your tail lamps work and that you checked fuses. The most important fuse to have checked would be the 10 Amp fuse in the right hand Instrument Panel Endcap fuse center called "INST LPs". It is the one on top kind of by itself.
Your comments on aftermarket radio are interesting but does it actually have any backlighting which varies in intensity based on rotating the dimmer switch?
I have some additional suggestions but provide back response on these questions first
Thank you.