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Home >> Mercury >> 2008 >> Milan Base, 3.0 1, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 513 (Rear View Mirror -- F250-F550 Super Duty) >> Diagnosis And Testing >> Rear View Mirrors >> Principles of Operation >> Auto-Dimming Mirror

Auto-Dimming Mirror

WARNING: This page is about a different car, the 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The interior rear view mirror may be equipped with an auto-dimming option. This feature automatically reduces the glare caused by headlamps reflecting in the mirror. The auto-dimming feature is disabled when the vehicle is in REVERSE. Power is supplied to the auto-dimming interior mirror when the ignition is in the RUN or ACC position.

The automatic dimming feature has 2 photoelectric sensors that detect forward and rear light conditions. Based on these inputs, the automatic dimming feature adjusts the reflectance level of the mirror glass to eliminate unwanted glare. The reflectance level of the mirror glass is variable and depends on the amount of rear glare in relation to ambient light conditions in front of the interior mirror.

When the forward sensor detects daytime conditions, the rear sensor is inactive and the mirror stays in a high reflectance mode. When the forward sensor detects nighttime conditions, the rear sensor is active and detects glare from the headlights of vehicles approaching from the rear or other glare-producing light sources. To provide increased visibility when backing up, the mirror will automatically return to a high reflectance mode whenever the shifter is placed in REVERSE.

If the forward or rear sensors are blocked, the automatic dimming interior mirror might not work correctly.