1997 GMC Sonoma Owner's Manual - Page 94

Front Map Lamps(If Equipped) If your vehicle has optional front map lamps, they are located on the inside rearview mirror. They will automatically come on for approximately 20 seconds when either front door is opened or unlocked with the Keyless Entry System, if so equipped, or until the ignition key is turned to RUN or ACCESSORY. The lamps will also stay on for approximately 15 seconds after you exit the vehicle, They will also stay on for 15 seconds when the INT LIGHTS switch on the instrument panel is turned on then off, while the ignition is off. You can also turn the lamps on and off by pressing the switch near each lamp. Mirrors Inside Daymight Rearview Mirror Dome Lamp Turn the INT LIGHTS dimmer switch up until it clicks to turn on the dome lamp. Press the tab under the mirror to reduce glare from headlamps behind you. 2-46