Retrofit 2002 ML exterior mirrors with lights to 2001 - Why can't it be done?
 

Just got an e-mail response to my question if I can upgrade the 2001 ML mirrors to the 2002 which have the lights. They told me it can't be done. Why? It doesn't seem to be that hard. The new mirror is the same shape and I already have electrical wires because it's the power mirror on the ML55.

You can, but you probably have to splice in the turn signal wires from either the rear or the front. Depending on how you do this, it will change either the resistance, voltage, or amperage of your indicator circuit, or all of them. If you go to the parts counter they'll tell you that you need a different wiring harness. I'd stay away from it. Too much trouble give that you have to essentially fabricate a new harness.

Kuan