Automatic Day/Night Mirror: Operation

The ambient photocell is located on the forward facing (windshield side) of the rear view mirror is the mirror housing, and detects the ambient light levels outside of the vehicle. The headlamp photocell sensor is located inside the rear view mirror housing behind the mirror glass and face rearward, to detect the side to the light being received at the rear window side of the mirror. When the circuity of the automatic day/night mirror detects that the difference between the two light levels is too great (the light level received at the rear of the mirror is much higher than that at the front of the mirror), it begins to darken the mirror.

The automatic day/night mirror circuity also monitors the transmission using an input from the backup lamp circuit. The mirror circuity is programmed to automatically disable its self-dimming feature whenever it senses that the transmission backup lamp circuit is energized.

The automatic day/night mirror is a completely self-contained unit and cannot be repaired. If faulty or damaged, the entire mirror assembly must be replaced.