Auto Dimming Mirror

[Trickythemerc]

Evening All. The drivers side mirror on my CLK has stopped auto dimming, the interior mirror still works as it should. There are no signs that the mirror glass has failed so I need to test for output from the interior mirror, question is what sort of voltage should I have at two wires going to the door when the interior mirror is dimmed.

 

[Diesel Benz]

The output from the interior mirror is a CAN message. The side mirror dimming is controlled by the door control module. I'd first measure the door control unit output, then change the mirror glass.