GM Service Manual Online
For 1990-2009 cars only

This feature prohibits dimming of the digital displays and backlighting during daylight hours when the key is in the ignition and the headlamps are on. This feature operates with the light sensor for the Twilight Sentinel and is fully automatic. When the light sensor reads darkness outside and the parking lamps are active, the digital displays can be adjusted by turning the instrument panel brightness knob counterclockwise to dim and clockwise to brighten lighting.