GM Service Manual Online
For 1990-2009 cars only

Your vehicle may have a dome lamp. Your vehicle may have a dome lamp without a switch. If your vehicle does have a dome lamp with a switch, the following are the settings.

(Off): Move the lever to this position to turn the lamp off, even when a door is opened.

(Door): Move the lever to this position to turn the lamp on whenever a door is opened.

(On): Move the lever to this position to turn the dome lamp on.