Cadillac: 97 cadillac sts, cigar lighters, analog instrument

Question
i have a 97 sts that the instrument cluster back lighting goes out after about 30 seconds and ive noticed it does it at the same time the courtesy lights time out.

Answer
Digital or analog instrument panel lighting ?.

This is a FIRST. Has the radio and or anything electrical been added or replaced recently or in the past ?.

Does the cigar lighters go inop also when the instrument back lighting goes out ?.

Did you check your Engine compartment MIRROR FUSE (10 AMP)?