Chevrolet Equinox Service Manual: Automatic Day-Night Mirror Description and Operation

Inside Rearview Mirror with the Automatic Day-Night FeatureSystem Operation

The inside rearview mirror uses 2-photocellsensors. One sensor is the headlight sensor, located on the faceside of the mirror. The headlight sensor is used to determine lightconditions present at the mirror face. The other sensor is theambient light sensor, located on the rear of the mirror orwindshield side. The ambient light sensor is used to determine theexterior light conditions. With a low exterior light conditiondetected, and a high light condition from behind of the car, at theheadlight sensor, the inside rearview mirror will automaticallydarken the face of the mirror.

In the daytime, the mirror is in a normal state because ofthe high exterior light condition that is indicated by the ambientlight sensor. With the gear selector lever in the REVERSE positionand the engine running, backup lamp supply voltage is supplied asan input to the inside rearview mirror. The mirror monitors thisinput to disable the automatic day-night feature. This allows thedriver to see objects in the mirror clearly when backing up, evenduring the night.