Automatically Dimming Inside Rearview Mirror, Function

Automatically Dimming inside Rearview Mirror, Function

Function requirements
- No overvoltage/undervoltage
- Circuit 15R or circuit 15 ON

Function
The glass of the inside rearview mirror unit (A67) can be electrochromatically dimmed. The mirror glass between the reflector and the glass cover contains a layer of electrolyte gel. The light transmission ratio of this gel changes when a voltage is applied to it.
The inside rearview mirror unit (A67) relates the light shining in from the rear in proportion to the ambient light, calculates the necessary degree of dimming, darkens the mirror surface and supplies the dimming information to the overhead control panel control module (N70).

The interior rearview mirror unit (A67) dims the mirror between 6 % and 80 % in line with the voltage applied (U=0 V up to 1.5 V). The two input parameters are detected by the mirror dimming forward sensor (A67h1) in the mirror housing (rear) and by the mirror dimming to rear sensor (A67h2) in the mirror lens of the inside rearview mirror unit (A67).

A CAN message is transmitted if an interior light is switched on, over the interior CAN or if reverse gear is engaged, over the engine compartment CAN, whereupon the inside rearview mirror unit (A67) in this case is rapidly switched to the maximum brightening state. This is ensured by an additional signal line from the overhead control panel control module (N70) to the inside rearview mirror unit (A67).

NOTE: The inside rearview mirror unit (A67) is the master for the outside mirror dimming (driver side).