Onizukachan
Great Teacher
Cool, never seen one that way but we used to run them switch power and ground only on 89 5 series since they didn’t hav3 the reverse lead on the headliner factory, they jsut didn’t undim in reverse. Not saying you are wrong at all, just Never seen on3 need constant and switched, especially not for homelink. It shouldn’t lose programming, none of mine ever did even with the car batteries disconnected for hours or days or even months. Not on mini, nor bmw pinned gentex, nor even the magnetti morelli I had till I swapped over to gentex in my e46.Never say always. There are always exceptions to the rule. The Kia auto dimming with compass but without the homelink is a 2 wire mirror. I have one of these brand new for one of my vehicles. The homelink adds the 3rd wire for the memory.
but GM/Kia may have cheaped out on them and used eprom instead of flash memory or something.