Quote:
Originally Posted by BMWZ4
Ha...I didn't know that. Learned something new.  |
NP.
Actually, to be rigorous correct, it uses two sensors on the RV mirror, the one mentioned above and the small circular one at the top center of the mirror side.
The ECU measures the difference between the front and rear mirror sensors, and darkens the mirror when the light detected as coming from the front of the car is less than the light coming from the back. When you cover the sensor on the windshield side during the day, it registers as a big difference between the front and back light levels, with the front being much darker.
Conversely, if you cover the small round sensor on the mirror side of the RV mirror, it prevents the mirror from darkening at all. I know someone who made a small open/closed cover for that sensor from the top of a TicTac box. He flips it open when he wants the autodarkening to work, and closes it when he doesn't.