Steve,

Here is another thread about the auto dimming mirror:
W126 - Modification of Rear-View Mirror

It is a easy DIY modification and if you have any other question after reading that thread, just let me know.

greetingz,

__________________
1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)