The switch only works on the passenger door mirror. But the function is flaky. Pressing the switch only works when reverse is engaged, but I've never found them reliable, and the mirror reverts to normal when you go forward again. It's a pain if you have to shuttle to and fro to get into a parking space.
I have worked round this. I have programmed button 2 on the memory seat to leave the seat in the same place but to dip both mirrors. That way they stay dipped until I want to drive off again.