Inside Rearview Mirror Dimming, Basic Function - GF68.49-P-9900A

Model All (4XWD) 

with code 249 (Automatic dimming inside rearview mirror and outside mirrors) 

Model All (CAR) 

with code 249 (Automatic dimming inside rearview mirror and outside mirrors) 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 

General 

The "Auto dimming inside rearview mirror" function protects the driver from being dazzled by following traffic.

Function requirements 

• No overvoltage or undervoltage
• Circuit 15R ON
• Reverse gear not engaged
• Interior illumination not switched on

Function 

For the function, two photo sensors installed in the mirror measure the brightness difference between the traffic area in front of and behind the vehicle. The inside rearview mirror evaluates the sensor signals and if the light intensity behind the vehicle is greater than in front of the vehicle, it dims the mirror glass.

For this purpose, the inside rearview mirror has a special electrochromatic layer on the glass. This contains electrolytes consisting of uniform crystals, similar to a LCD display. The inside rearview mirror applies a voltage to this layer, the crystals align themselves in a specific angle as a result. This leads to an immediate and depending on the light intensity and sensor measurement to a continuously variable darkening effect.

The inside rearview mirror also transmits the dimming request to the outside mirrors.

	Additional basic functions
	Automatic dimming of mirror glass of outside mirror, basic function		GF88.79-P-1000A
	Function schematics
	Function schematic for automatic dimming of mirror glass of inside and outside mirrors	Model 118, 167, 177, 247, 293 with code 249 (Automatic dimming inside rearview mirror and outside mirrors) Model 213, 238, 257, 290 as of model year 2021 with code 249 (Automatic dimming inside rearview mirror and outside mirrors) Model 243 with code 249 (Automatic dimming inside rearview mirror and outside mirrors)	PE88.79-P-2501-97A
		Model 192, 206, 214, 223, 232, 236, 254, 294, 295, 296, 297 with code 249 (Automatic dimming inside rearview mirror and outside mirrors)	PE88.79-P-2501-97B