1998 GMC Sonoma Owner's Manual - Page 107

Battery Run-Down Protection This feature shutsoff the dome, courtesy, vanity, reading, glove box, cargo and underhood lamps if they are left on for more than 20 minutes when the ignition is off. This will keep your battery from running down. Mirrors Electrochromic Day/Night Inside Rearview Mirror If the batteryrun-down protection shuts off the interior lamps, to return to normal operation it may be necessary to: 0 Shut off all lamps and close all doors, or Turn the ignition key to RUN. 0 Your vehicle may have an automatic electrochromic dayhight rearview mirror. This mirror autornatically changes to reduce glare from headlamps behind you. A photocell on the back of the mirror senses when it is becoming dark outside. Another photocell built into the mirror surface senses when headlamps are behind you. 2-43