I have a new to me 2017 CR-V with the automatic rear view mirror dimming feature. How can I tell if it is on or working? There are no lights glowing at the bottom of the mirror at night or when the headlights are on. Is there an on/off switch somewhere? I have looked in the online owner's manual and it just says this feature is always active and will turn off when the vehicle is in reverse. How can I tell if the dimming feature is really working?