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

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

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

Function prerequisites
- Key in ignition lock in position 2 (C. 15)
- Dome light switched off
- Reverse gear not engaged
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.
A control module integrated into the inside rearview mirror compares the signals from the two sensors (2 and 3).
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.