Sox is saying the thumbwheel dash light dimmer switch next to the light switch (to the left of the steering column) has 2 setting for dash/interior light control. In the 2nd from the top notch (look at the printed marks to the left of the thumbwheel), the dash lights remain at 100% brightness all the time. Move the switch a postion below the 2nd notch and the day/night feature on the radio will work. The top notch is all interior lights on all the time. All the way down is everything off all the time.
Personally, I have mine set to 100% brightness all the time because the radio switching back and forth while drive (near dusk, going thru tunnels, etc) sync'ing with the auto headlights was driving me a little nuts.
2012 GC Owner's Manual, Page 187:
Courtesy and dome lights are turned on when the front
doors are opened, when the dimmer control (rotating
wheel on the right side of the headlight switch) is rotated
to the its farthest upward position, or if equipped, when
the UNLOCK button is pressed on the Remote Keyless
Entry (RKE) transmitter. When a door is open and the
interior lights are on, rotating the dimmer control all the
way down, to the OFF detent, will cause all the interior
lights to go out. This is also known as the “Party” mode
because it allows the doors to stay open for extended
periods of time without discharging the vehicle’s battery.
The brightness of the instrument panel lighting can be
regulated by rotating the dimmer control up (brighter) or
down (dimmer). When the headlights are on you can
supplement the brightness of the odometer, trip odometer,
radio and overhead console by rotating the control
to its farthest position up until you hear a click. This
feature is termed the “Parade” mode and is useful when
headlights are required during the day.