You mean the mirror control? I know there is a little light that comes on when you press a certain button but i thought that was to just activate the mirror controls.
If that's it I know I won't be able to resist playing with it now lol.
What i did was undid the window and actually felt the mirrors to check they were actually hot... it will help u when washin the car too as its hard to chamois them as water sticks around but juss whack on the ol heated mirrors and as if by magic the water is gone
I've had to use my scraper on my cars windows the last few mornings, but I doubt we'll get any snow where I am, it never snows here I'd be happy with just 1 or 2 inches of snow, makes for an interesting driving experience which I want to do again