Rear View Mirror

The auto dimming mirror has nothing to do with darkness. In fact, it's the opposite--it's activated by the *presence* of light. The little sensor on the opposite side of the green "on" LED is the photocell. Whenever *any* light is present it dims the mirror. The more direct light into the sensor, the more the mirror dims. It is designed like this so when a car is directly behind you shining its headlights at your mirror, you get maximum dimming. As soon as the car goes away the mirror lightens some to help you see behind you at night when there's no direct light source.

Try this on a bright sunny day. Close your sunshade on the moonroof and turn the mirror on. Give it about 15 seconds to adjust to the ambient light (it doesn't change instantaneously). Then slide open your sunshade and watch what happens. Even though it's not direct light it's enough to dim the mirror.

You can also take a flashlight (day or night) and shine it at the sensor and watch the mirror dim. Conversely, at night when a car is behind you and it is full dim, you can put your thumb over the sensor and the mirror will switch to full lightness.

This is why it does function in the daytime and why there is a switch to turn it off