1997 Cadillac Seville Owner's Manual - Page 113

This mirror automatically 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 intothe mirror surface senses when headlamps are behind you. At night, when the glare is too high,the mirror will gradually darken to reduce glare (thischange may take a few seconds). The mirror will return to its clear daytime state when the glare is reduced. Press the button at thebase of the mirror to turn on the automatic feature. The button has an indicator light to show it is on. Press the button to turn the automatic feature off.