2006 Cadillac DTS V8 Front Wheel Drive Automatic 30000 miles
I keep the dash lights turned low for night driving. About 2/3 of the time when I drive in daylight the dash brightens up (brighter than it can be adjusted with the switch). The other 1/3 of the time it stays nearly black during daylight hours. I turn it up and drive it, but can't see it as well as I should. Then sometimes during the trip, it will suddenly brighten up into the daylight mode. Or sometimes it is the opposite; I start out and it is fine and later will suddenly become dark. Is there a daylight sensor somewhere that is possibly dirty or defective?
I am not going to say there is something wrong, nor am I going to say there is not something wrong. Is the changes in panel brightness coincidental with shade, like driving through trees, buildings, etc. I would say that your automatic headlamps are also going on and off. The twilight sensor is in the center of the dash, forward of the center speaker. Try this for a test, when driving in daylight hours, switch the automatic headlamps off. Take note if, and how regularly, a 'headlamps suggested' message appears, I would also say the dash light issue won't occur. If you are keeping your panel lights dim for night driving, it may be too dim in the daytime when the system feels it needs headlamps. There is no sensitivity adjustment for the automatic headlamps. About the only possibility for fault, is the twilight sensor dropping down in the dash, it would register lower light earlier than normal. You should be able to see the photocell through the lense, it may take a flashlight, or equivalent. The automatic headlamps will come on in daylight conditions when the the wipers are turned on, as well. There is no bulletins, or even a diagnostic procedure for automatic headlamps coming on inadvertently. The lights are controlled by the body control module, the twilight sensor is a direct input to the body control module. A check would have to be performed with a scan tool, if nothing visual stands out. There is an ambient light sensor voltage, as well as a night/day or unknown/invalid status that could be viewed.