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temperture control and outside temperture display

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by hc167, Mar 23, 2015.

  1. hc167

    hc167 Member

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    It was a cold winter in Boston in the last two months. And since then almost everytime I started my 2005 Prius, the temperature was default to 75F. Is there anything I can do to fix it? Also, the first time I start the car in a day, it almost show the outside temperature as Celsius instead of Fahrenheit unless I press the screen to display something else and then come back, then the Fahrenheit will come back. Is there anything to fix it? Thanks
     
    #1 hc167, Mar 23, 2015
  2. Britprius

    Britprius Senior Member

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    Make sure the wires to the temperature sensor are not damaged and that the connector has clean contacts. It is mounted on the center metal vertical support strip in front of the radiator.
    It could be the sensor it's self that is faulty. This can be checked with an ohm meter set to 2k ohms connected to the sensor. Warming the sensor with your hand should make the reading fall.

    John (Britprius)
     
    #2 Britprius, Mar 23, 2015
  3. Mylar

    Mylar Member

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    A new ambient air temp sensor part # 8879022131 is relatively cheap (Under $20). I had to replace mine because the plastic clip holding it to the frame broke and could not be purchased separately.
     
    #3 Mylar, Mar 23, 2015
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  4. hc167

    hc167 Member

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    Why do you think the issue is the sensor? My car detect temperature correctly. it just showing Celsius instead of Fahrenheit initially
     
    #4 hc167, Mar 24, 2015
  5. hc167

    hc167 Member

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    Why do you think the issue is the sensor? My car detect temperature correctly. it just showing Celsius instead of Fahrenheit initially
     
    #5 hc167, Mar 24, 2015
  6. Mylar

    Mylar Member

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    Once you select F in the MFD, it should always default to that setting. You shouldn't have to continually change it. My reasoning for changing out the sensor is it's cheap, and it may solve your problem.
     
    #6 Mylar, Mar 24, 2015
  7. hc167

    hc167 Member

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    I don't think there is an option for me to change to C or F. anyway. I do not believe this is sensor issue. I believe this is internal computer hardware issue that I need to reset the MFD hardware to make it behave normal again. I am just wonder if there is anyone know the way to reset the MFD. Otherwise, I will try to disconnect it from battery.
     
    #7 hc167, Mar 26, 2015
  8. Britprius

    Britprius Senior Member

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    As far as I am aware there is no volatile memory in the MFD so disconnecting the battery will accomplish nothing.
    In your first post #1 you say that the weather was cold in Boston presumably you mean around 32 F, but you have a reading of 75 F, "quite warm to most" and then in your post #4 you say this reading is correct.
    Checking condition of the wiring the resistance of the sensor will cost nothing but time, and will eliminate it from the equation if all is well. You seem fixated on it being the MFD, and it may be, but surely you eliminate the easy and cheap possibilities before the expensive complicated components that require dismantling of the dashboard to check out.
    If you do not heed the advice given why ask for it?

    John (Britprius)
     
    #8 Britprius, Mar 26, 2015
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  9. hc167

    hc167 Member

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    OK. I understand the confusion now. The reading is already correct. It just show C instead of F for the outside temperature. I remember my car have been showing outside temperature in F, not C. Now, second issue, for the temperature control. It is now default to 75F (yes, somehow it still use F for climate control) even my last driving I set it to something else. In which the climate control always set to what I set from last time. Now, it just sometime use my previous setting, sometime it default to 75F. That is why I am thinking of resetting the entire MFD. But don't know how to do it except unplug from the battery
     
    #9 hc167, Mar 30, 2015
  10. Dodge Aries K

    Dodge Aries K Junior Member

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    Bumping this up haha. My 2005 Prius does the same thing after it sits for more than a few hours. The display will show the outside temp in Celsius and the climate control resets to 75 degrees. Was the answer to this odd issue ever found? I've been thinking that I should just replace the 12 volt battery (since I think it's original and therefore over 10 years old) but before I spend money on it, be nice to know if that fixed the issue for anyone else.
     
    #10 Dodge Aries K, Oct 16, 2015
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