Automatic dimming inside rearview mirror, function - GF68.49-P-0003AA

MODEL 129, 140, 210 as of 1.6.96 with CODE (491) U.S. version with CODE (625) Australian version 

MODEL 202 as of 1.8.96 with CODE (491) U.S. version with CODE (625) Australian version 

MODEL 129, 140 / / / /, 202 (except 129.076, 140.056 /057 /076 /063 /070) as of 1.6.97, 210 as of 1.3.97 with CODE (249a) Automatic dimming inside rearview mirror 

MODEL 170 as of 1.12.97, 129.076, 140.056 /057 /076 /063 /070 as of 1.6.97 

MODEL 210 as of 1.3.97 with CODE (954a) Avant-garde 

MODEL 210 as of 1.3.97 with CODE (955a) Elegance 

Fig 1: Identifying Automatic Dimming Inside Rearview Mirror Components

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Function sequence 

1. Function prerequisites
   • Key in ignition lock in position 2 (C. 15)
   • Dome light switched off
   • Reverse gear not engaged
2. The ambient brightness is measured by the sensor (2) in the inside rearview mirror housing.

   Simultaneously a second sensor (3) on the surface of the rearview mirror measures the light intensity hitting the mirror.

3. A control module integrated into the inside rearview mirror compares the signals from the two sensors (2 and 3).
4. If the intensity of the light reaching the surface of the inside rearview mirror is greater than the ambient brightness, the outside rearview mirror is dimmed by the control module in the inside rearview mirror.