I have a question, I have a 99 300M and I bought a replacement mirror but accidentally didn't buy a heated mirror, so I was wondering if there was a way I could replace the heating mechanism on the new mirror, since I bought it on Ebay and can't return it?

 

If you still have the wiring harness from the old mirror, there are two wires that run to the mirror glass itself. You would need to add these, and the mirror glass.

 

Okay.... so How do I remove the glass, because I tried to remove it but I couldn't figure it out.

 

That, I would have to check out in person. Is there any way you can take a picture of the back side of the mirror? I understand it would be best possible, but I should be able to give you direction on how to remove the glass. If you move the mirror in the furthest direction so as to see behind it with a flashlight, you can make a decision how it was attached. Sometimes there are clips at the bottom to let loose, and then the mirror glass slides out at the top. Some glasses have a 3 1/2 inch circular "base" on the mirror glass and has clips spaced around the circumference, with double sided tape holding it for vibration, some mirrors have a center pivot, and two "screws" for adjustment top and side. I hope this helps somewhat, but if pictures are possible, please post them.