Self-darkening rear view mirror

Discussion in 'Gen 3 Prius Main Forum' started by Yaesu, Mar 31, 2019.

  1. Yaesu

    Yaesu Junior Member

    Joined:
    Nov 19, 2016
    92
    24
    0
    Location:
    Kentucky
    Vehicle:
    2010 Prius
    Model:
    IV
    I would like to know how the mirror darkens at night. Does it sense headlights or does it sense darkness? I wish the mirror darkened a bit more, because some of the HID or LED headlights are too bright in the mirror.
     
  2. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    15,192
    10,577
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    If you look closely, you can see it has a photocell facing forward, and a photocell facing rearward. It compares the brightness forward (so it doesn't dim as much when it's light out) to the brightness from the rear (so it dims more when stronger light falls on that cell). If you put some partially light-absorbing film over the front sensor, it will tend to dim more, or you could put the same stuff over the rear sensor, and it would tend to dim less.

    The Prius presents an interesting design issue because of the split rear window. Depending on the height of the car that's following me (or height of their headlights, anyway) and their following distance, and also my height and the aim of my mirror, sometimes their headlights shine all over inside my car, including right in my mirror and full-on in my eyes, but the shadow cast by the spoiler just happens to fall right at the bottom edge of the mirror where the sensor is, so it doesn't sense the light, and it doesn't dim.

    And somehow, people following me seem to have an instinctive sense for the exact right following distance to make that happen, and maintain it for 20 miles.

    There was a post here some years back where somebody just rotated the mirror so it's upside-down with the buttons and sensor at the top edge, and it solved the problem for them. :)
     
  3. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    95,314
    43,206
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    i think it senses headlights. i don't like them, prefer the cheapo flip mirror, but i'm sensitive to glare.
     
  4. Yaesu

    Yaesu Junior Member

    Joined:
    Nov 19, 2016
    92
    24
    0
    Location:
    Kentucky
    Vehicle:
    2010 Prius
    Model:
    IV
    ChapmanF,
    Thank you for the detailed explanation of how the light sensors work on the mirror. I was curious because one time when I backed out of the darkened garage during the daytime, the mirror was dim until I got out in the sun.

    The problem with following headlights in the mirror is sometimes a problem in FL, but when we are in KY, they follow so closely that I don't see their headlights.
     
  5. bettergolf

    bettergolf Active Member

    Joined:
    Jan 8, 2019
    277
    253
    0
    Location:
    Sanford NC
    Vehicle:
    2015 Prius
    Model:
    Two
    I agree on the cheapo flip mirror. My 2015 being salvage, the windshield was replaced and they stuck on a plain old flip mirror, which I have missed terribly for years now. Everybody has lasers nowadays for headlights...especially the high trucks which from behind is like having a WWII search light in your rear window.
     
  6. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    95,314
    43,206
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    a lot of todays headlights are illegal, or should be
     
  7. Yaesu

    Yaesu Junior Member

    Joined:
    Nov 19, 2016
    92
    24
    0
    Location:
    Kentucky
    Vehicle:
    2010 Prius
    Model:
    IV
    I find that some of the projector type headlights (HID and LED), whether or not they are OEM can be much too bright in certain situations. Because of their intense focus and sharp cut off, if the vehicles are on an incline, the lower portion of the beam can be bothersome. Having old eyes contributes to the problem.
     
  8. padroo

    padroo Senior Member

    Joined:
    Jan 11, 2008
    2,763
    2,243
    13
    Location:
    Chesterton, Indiana Another third world country.
    Vehicle:
    2016 Prius
    Model:
    Four
    Yes everyone hates the new headlights except the people who have them.

    I get people flashing their headlights at me all the time and they are on low beam.
     
  9. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    10,242
    12,569
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    My 2005 had the automatic mirror. I hated that thing!!!
     
    WilDavis likes this.
  10. WilDavis

    WilDavis Senior Member

    Joined:
    Feb 4, 2014
    2,463
    2,117
    49
    Location:
    Top RH Corner of RH Coast on L side of The Pond
    Vehicle:
    2009 Prius
    Model:
    II
    …same here, and I prefer to dip my own headlights, floss my own teeth, and wipe my own bum (so many things are getting automated these days, "…Arms that can only lift a spoon
    You see everyone's gone, everybody's gone
    Everyone's gone to the moon
    Everyone's gone to the moon" (Kenneth King) o_O :(
     
    bisco likes this.
  11. padroo

    padroo Senior Member

    Joined:
    Jan 11, 2008
    2,763
    2,243
    13
    Location:
    Chesterton, Indiana Another third world country.
    Vehicle:
    2016 Prius
    Model:
    Four
    I thought I was the only one who never liked those auto darkening mirrors.
     
    jerrymildred and WilDavis like this.
  12. WilDavis

    WilDavis Senior Member

    Joined:
    Feb 4, 2014
    2,463
    2,117
    49
    Location:
    Top RH Corner of RH Coast on L side of The Pond
    Vehicle:
    2009 Prius
    Model:
    II
    Ah, there are but few of us still remaining! I love driving, and that includes having total control of everything in my car (all the controls, that is!) and that includes gears, engine, clutch, brakes, lights, ventilation, heater, air-conditioning, music, wipers, seat-belts etc. etc. It saddens me when I see just how society is being dumbed-down! :(
     
    jerrymildred likes this.
  13. Grit

    Grit Senior Member

    Joined:
    Aug 22, 2017
    5,302
    3,739
    1
    Location:
    Wilkes Land
    Vehicle:
    2012 Prius
    Model:
    Four
    I’m still trying to figure out how to set default mirror to off when engine on ready. Haven’t had the long chance to jump on. Techstream for capability.
     
  14. Montgomery

    Montgomery Senior Member

    Joined:
    Sep 11, 2015
    1,898
    1,951
    2
    Location:
    Orange County, CA
    Vehicle:
    2015 Prius
    Model:
    Two
    Ahh, the essence of projection lights. For me, the reason for people wanting brighter lights is because the person coming towards them has bright lights and once you pass the cars, your eyes take longer to adjust back to a level you can see. So, people buy the brighter lights, thinking that the issue has been solve. Well it has, but the main problem hasn't been bulb brightness, it's our eyes trying to adjust back after being hit with bright lights, thus the contiuning cycle of brighter and brighter lights being sought.
     
    WilDavis and jerrymildred like this.
  15. bettergolf

    bettergolf Active Member

    Joined:
    Jan 8, 2019
    277
    253
    0
    Location:
    Sanford NC
    Vehicle:
    2015 Prius
    Model:
    Two
    True...I hear people say "they're safer because now I can see so much better at night!". Problem is, everyone else is blinded so they only feel safe, not understanding the other drivers can't see anything at all. I've had cases where I had to just hope nothing rand out in front of me or hope that I don't run off the road until those atomic headlights pass by me.....totally blinded sometimes for up to 4-5 seconds.
     
    jerrymildred likes this.
  16. padroo

    padroo Senior Member

    Joined:
    Jan 11, 2008
    2,763
    2,243
    13
    Location:
    Chesterton, Indiana Another third world country.
    Vehicle:
    2016 Prius
    Model:
    Four
    I am glad when the days get longer and I am usually home before dark when I can be. I don't like blinding people but what to do about it and I don't see it getting any better as brighter and brighter headlights come out. It doesn't help getting older and your night vision deteriorates either.
     
  17. Maarten28

    Maarten28 Active Member

    Joined:
    Jul 13, 2014
    414
    220
    1
    Location:
    Netherlands
    Vehicle:
    2011 Prius
    Model:
    Three
    Yeah, my rear view mirror usually does not dim. It does occasionally so it is not broken, but most of the times it does not dim even though there are very bright lights in the mirror and I want it to dim.
    I've also assumed this is connected to the spoiler and I've tried turning the mirror 180 degrees to see if the sensor would pick the lights up better, but that made no difference. Now I'm just thinking if I could mod the mirror to have the button not cancel the auto dimming, but force the mirror to dim.

    It is incredible that this flaw was not spotted by the Toyota testers.
     
  18. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    15,192
    10,577
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    If I can pull far enough ahead or drop far enough back toward the following car so the light from their headlights actually lands on the sensor then my mirror will dim.

    The trouble is just that the following driver usually really likes the exact following distance where that doesn't happen.
     
  19. The Electric Me

    The Electric Me Go Speed Go!

    Joined:
    May 22, 2009
    9,083
    5,778
    0
    Location:
    Undisclosed Location
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    I'll preface this with the admission that I've never owned a vehicle that did have a self dimming mirror.
    But I've never really wanted one. Sometimes I think the simpler solution to the problem, is the best, and the flip technology is fine with me.

    Also, I've never needed any help being dim.
     
    padroo and WilDavis like this.
  20. WolfpackBill

    WolfpackBill Active Member

    Joined:
    Mar 28, 2014
    337
    489
    6
    Location:
    Lexington, NC
    Vehicle:
    2010 Prius
    Model:
    IV
    I agree with you guys. I have had auto dimming mirrors in different cars (even some with both auto-dimming wing mirrors) and they work great but it does not work for our Prius. That dang spoiler is right in the line of sight of the sensor. I actually prefer the regular manual day/night mirror for this generation Prius.

    Not sure about the 4th gen hybrid but my bro-in-law just bought a 2018 Prius Prime Advanced and we drove it at night and that mirror works perfectly!! The sight line is low enough for the mirror to catch all the glare so it can dim.
     
    WilDavis and padroo like this.
Loading...