Auto-Dimming Rear-view Mirror Override (Electrochromic)

thingiverse

I drive a 2013 Subaru with an automatic dimming mirror that's normally reliable, but I've encountered several instances where it fails to adjust its brightness when it should. The problem tends to occur at dawn or dusk when the ambient light from the sky is intense. The need for this device arose from my frustration with the lack of a manual override on the existing system. This simple solution allows me to manually control the dimming by positioning a small slider that blocks the light from entering the rear-view mirror, fooling it into thinking it's nighttime. To attach the device, I use 3M trim tape available at auto supply and hardware stores.