Are my preset radio buttons ALL suppose to illuminate,also both temperate slides on 2004 Chevrolet Trailblazer

just bought vehicle. only buttons 1, 2 are illuminating at dark, along with only one side of the temperature slide for vents. Nothing in manual about illumination. Hard to see them at night.

Asked by for the 2004 Chevrolet Trailblazer
poss bad bulbs or circuit board inside.not sure if they are servicable in these units