1998 GMC Safari Owner's Manual - Page 123

The dome lamps will come on when open any of the you doors. They will remain for 20 seconds after the last on door closes. When ignition switch is turned the the on, dome lamps willgo off. You can also turn on the dome lamps by turningthe dimmer dial up to second click. the If the DOME OVERRIDE button pushed in, the dome is lamps will not come on. If the DOME OVERRIDE button is out, your interior lamps will workas usual. If the buttonis pressed in, the interior lamps will not come on when any of the vehicle's doorsare open. The button is located next to the lamp switch. If you have the optional reading lamps, they will still operate if the button is pressed in. Dome Override Button Reading Lamps (Option) You may have the optional reading lamps next to the dome lamps. Turn lamps on and by pressing the the off switch next to the lamp. You can adjust the lamps to any desired position by rotating the lamp and they will work when the ignitio is on oroff. Be sure to turn the lamps before you off leave the vehicle. 2-39