Instrument Panel Dimming

[dshield]

We're talkin' about an '03 GCL. WHen the headlights go on the instrument panel lights are supposed to dim, including the information panel in the ceiling and the display on the radio.

Trouble is they dim to the point that they appear to be off when driving in daylight. So, on a rainy day, with the wipers and headlights on, one can not read the radio display, or the info center in the ceiling. At night, not a problem, they're bright enough to see.

I'm reading up on the schematics in my Haynes book and they refer to an "instrument panel dimming/drl module". Anybody know where it is? Or, can anyone point to a possible root cause? Could it be the headlight switch on the steering column?

Thanks.

Dshield