Outside temperature sensor

Discussion in 'Gen 2 Prius Main Forum' started by marjam, Jul 6, 2006.

  1. marjam

    marjam Member

    Joined:
    Jun 17, 2006
    220
    0
    0
    Location:
    Silver Spring, MD
    Does anyone know where the sensor is that tells the HVAC and the MFD what temperature it is outside? The location might explain some strange readings at times.
     
  2. mssmith95

    mssmith95 Michael

    Joined:
    Feb 1, 2006
    535
    4
    0
    Location:
    Valencia, CA
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Premium
    <div class='quotetop'>QUOTE(marjam @ Jul 5 2006, 09:27 PM) [snapback]281814[/snapback]</div>
    I think I remember others posting that it behind the front grill.

    So far, I have only had issues after a car wash, when it seem slow to recover. There was a thread about this a week or so ago.

    Other then that it always seems pretty close (it does take a few minutes between updates).

    What is your doing?
     
  3. Frank Hudon

    Frank Hudon Senior Member

    Joined:
    Jan 11, 2004
    4,147
    12
    0
    the climate control temp sensor is the one on the dash.
     
  4. marjam

    marjam Member

    Joined:
    Jun 17, 2006
    220
    0
    0
    Location:
    Silver Spring, MD
    <div class='quotetop'>QUOTE(mssmith95 @ Jul 6 2006, 12:42 AM) [snapback]281820[/snapback]</div>
    Mine is pretty accurate when compared to the radio forecasts and bank thermometers. But on both my Prii, it always moves in increments of 2 degrees. If you start the car and the temp is an even number any changes always go to even numbers. I bet in 5 years I have only seen the temperature change by one degree 4 or five times. It also registers high when the car has been parked for a while so I figure it must also pick up heat from the engine when the car is stopped.

    None of this is bad, I'm just curious. <_<

    <div class='quotetop'>QUOTE(Frank Hudon @ Jul 6 2006, 01:45 AM) [snapback]281852[/snapback]</div>
    The one on the dash is for inside temperature, isn't it? I mean outside tepmerature.
     
  5. galaxee

    galaxee mostly benevolent

    Joined:
    Mar 14, 2005
    9,810
    441
    0
    Location:
    MD
    Vehicle:
    2005 Prius
  6. etkal

    etkal New Member

    Joined:
    Apr 5, 2006
    64
    0
    0
    Vehicle:
    2012 Prius
    Model:
    Four
    I think my temperature sensor is defective and seems to have a lower limit. This morning it was well below 0 outside, but my car said it was 7ºF. In fact, it stayed at 7 for about half an hour before rising. I've seen this before, and have never seen it read anything below 7ºF. Is this a known issue? Does it not get below 7ºF in Japan? :-P
     
  7. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,054
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    <div class='quotetop'>QUOTE(marjam @ Jul 6 2006, 01:20 AM) [snapback]281870[/snapback]</div>
    The outside temperature sensor works in Celsius, then converts to Fahrenheit. There are 1.8 Fahrenheit degrees for every Celsius degree, so that is where you get the two degree increments.

    Tom
     
    Wonder likes this.
  8. ken1784

    ken1784 SuperMID designer

    Joined:
    Dec 18, 2003
    2,940
    1,348
    67
    Location:
    Yokohama, JAPAN
    Vehicle:
    2010 Prius
    Model:
    N/A
    <div class='quotetop'>QUOTE(Erik Tkal @ Mar 7 2007, 04:45 AM) [snapback]401058[/snapback]</div>
    My bet is the 7ºF is a kind of limitation on the system. It is not defective but a specification. :)
    In Japan, we saw -40ºC (-40ºF).

    [email protected]
     
  9. eej5

    eej5 New Member

    Joined:
    Apr 4, 2006
    9
    0
    0
    My outside temp reading always seems high compared to back clocks -- usually 4 to 6 degrees. I assume it picks up some heat from the car.
     
  10. dmckinstry

    dmckinstry New Member

    Joined:
    May 4, 2006
    1,034
    4
    0
    Location:
    Cheney, WA (Near Spokane)
    Vehicle:
    2005 Prius
    <div class='quotetop'>QUOTE(eej5 @ Mar 7 2007, 08:30 AM) [snapback]401685[/snapback]</div>
    I guesstimate the same difference, and assume for the same reason. The faster I drive into the wind, the closer I suspect the displayed temperature is to the actual outside temperature. Someday, I'll have to actually hand a thermometer out the window.

    Dave M.
     
  11. dwalkerw

    dwalkerw New Member

    Joined:
    Sep 8, 2006
    6
    0
    0
    I have noticed the same 2 degree increment. This past winter I saw a -6 for a low, so it must get colder than 7 degrees in Japan. My temp is usually 2 degrees warmer than most other references, no matter what the outside temperature is. I suppose some of it may be the round off error of the 2 degree increments.

    Dennis
     
  12. Leo

    Leo Leo

    Joined:
    Jul 18, 2005
    68
    11
    0
    Location:
    Ottawa, Canada
    Vehicle:
    2005 Prius
    <div class='quotetop'>QUOTE(DWalker @ Mar 7 2007, 07:40 PM) [snapback]401911[/snapback]</div>
    In Canada where we have Celsius, I find the outside temperature displayed is usually one degree C warmer than it really is out there. So your two degrees F difference may be partly due to the conversion, but also part of it is because it isn't all that accurate. All you have to do is make a mental correction.
    It seems however to get increasing inaccurate as the temperature drops. We had -24C this morning (-11F) and my display was showing -21C all the way to work. Also something that I want to check: 200 yards after I leave my heated condo's underground garage there is a traffic light. This morning, for example, the temperature on the display began plummeting as soon as I got out of the garage (naturally), dropping about one degree every couple of seconds. But as soon as I stopped for the light the temperature hung there without any change. Then when the light turned green and I began moving again, it continued on its plummet. I've noticed this a number of times. I was wondering if it doesn't monitor the outside temperature when it's stopped. On the other hand it could be the engine heat was holding it constant. I need to check that on a windy day.
    This conversion of C to F is only one of the bizarre designs in the Prius - what I call "What was Toyota thinking?" For example, the speedometer in Canada is in kilometers (metric), but the cruise control increments in mph (imperial). So in Canada we have the reverse situation with cruise control: if you flick the cruise control level up or down it increments in mph but still displays in kilometers.
     
  13. hobbit

    hobbit Senior Member

    Joined:
    Mar 23, 2005
    4,089
    459
    0
    Location:
    Bahstahn
    Vehicle:
    2004 Prius
    Model:
    N/A
    What Toyota was thinking was probably that the bullheaded stupid
    american adherence to non internationally standard and non-scientific
    units didn't count for much, so they do everything in MKS like they
    should and then make a token nod toward english units by converting
    if needed.
    .
    The sensor is only a NTC thermistor, and is not necessarily the most
    accurate device on the planet. I think mine reads about 2 F [see,
    duh] high too. It's plenty good enough for the ECM to make its
    determinations about running conditions, and that's what counts.
    .
    _H*
     
  14. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    42,856
    14,332
    41
    Location:
    Canada
    Vehicle:
    2018 Prius Prime
    Model:
    Technology
    Just note that your Fahrenheit display isn't true Fahrenheit. It's in Celsius and then converted which will explain why it skips numbers in °F
     
  15. deh2k

    deh2k New Member

    Joined:
    Jul 12, 2004
    241
    0
    0
    Location:
    New Hampshire
    Vehicle:
    2005 Prius
    <div class='quotetop'>QUOTE(Erik Tkal @ Mar 6 2007, 02:45 PM) [snapback]401058[/snapback]</div>
    Yesterday it was -17 F outside here, and that's what the MFD showed.
     
  16. John in LB

    John in LB Life is good

    Joined:
    Aug 5, 2006
    399
    27
    0
    Location:
    Orange County
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Advanced
    <div class='quotetop'>QUOTE(Tideland Prius @ Mar 7 2007, 08:11 PM) [snapback]402065[/snapback]</div>
    Folks, I may sound anal here, but the sensor itself is just a thermocouple and does not know anything about Celsius or Fahrenheit. Now it is possible that the software programmers were lazy and took the signal from the thermocouple and converted it into a celsius value first - then for purposes of displaying fahrenheit, they took that celsius value and converted it to fahrenheit - that could possibly result in a 2 degree jump between readings.

    PS: there is nothing inherently superior about celsius versus fahrenheit - its just a different scale - please don't get snooty on us... :blink:
     
    Wonder likes this.
  17. R1200GS

    R1200GS Junior Member

    Joined:
    Mar 5, 2007
    71
    0
    0
    Location:
    chicago
    Vehicle:
    2009 Prius
    Model:
    IV
    whats that other one? Kelvin? isnt my prius talking to me in Kelvin!!! B)
     
  18. HTMLSpinnr

    HTMLSpinnr Super Moderator
    Staff Member

    Joined:
    Dec 8, 2003
    5,339
    913
    251
    Location:
    Surprise, AZ (Phoenix)
    Vehicle:
    2018 Tesla Model 3
    Model:
    N/A
    <div class='quotetop'>QUOTE(John in LB @ Mar 8 2007, 06:41 AM) [snapback]402180[/snapback]</div>
    Consider the fact that most of the world uses the Celsius scale, it's probably easier/cheaper to hack Fahrenheit in for the minority that still utilizes that scale.

    Some scientists will beg to differ - Fahrenheit is a more granular scale which permits more precise measurement with fewer decimal places, especially at very low or very high temperatures.
     
  19. John in LB

    John in LB Life is good

    Joined:
    Aug 5, 2006
    399
    27
    0
    Location:
    Orange County
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Advanced
    <div class='quotetop'>QUOTE(htmlspinnr @ Mar 8 2007, 09:31 AM) [snapback]402257[/snapback]</div>
    There is not a chance in H--L that the above statement is true.... With that logic, you have more accuracy with a speedometer reading in KPH rather than MPH

    Give me the Quack's name that said that! :p
     
Loading...