Hyundai Elantra MD/UD: Automatic-dimming Function - Description and Operation - Electro chromic Inside Rear View Mirror - Body Electrical System - Hyundai Elantra MD 2010-2015 Service manualHyundai Elantra MD/UD: Automatic-dimming Function

To protect your vision during nighttime driving, your mirror will automatically dim upon detecting glare from the vehicles traveling behind you. The auto-dimming function can be controlled by the Dimming ON/OFF Button :
1.
Pressing and holding the Feature Control button for more than 3 but less than 6 seconds turns the auto-dimming function OFF which is indicated by the green Status Indicator LED turning off.
2.
Pressing and holding the Feature Control button again for more than 3 but less than 6 seconds turns the auto-dimming function ON which is indicated by the green Status Indicator LED turning on.
The mirror defaults to the "ON" position each time the vehicle is started.

Description
The ECM (Electro Chromatic inside rear view Mirror) is for dimming the reflecting light from a vehicle behind at night, Preventing glare from the light. The forward facing sensor detects brig ...