1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Engine Refuses to Turn Off at Red Lights?

Discussion in 'Gen 3 Prius Technical Discussion' started by Anthony E, Jan 5, 2017.

  1. Anthony E

    Anthony E New Member

    Joined:
    Jan 5, 2017
    3
    0
    0
    Location:
    Orlando, FL
    Vehicle:
    2010 Prius
    Model:
    II
    Hello there! I've noticed a problem with my prius today and would like some input. Normally, at almost every red light the ICE will turn off, except in certain cases when the battery is low, I have the heater on, etc. However, today, the engine did not turn off once. Even at a red light with the battery fully charged, no heater or AC on, and the temperature was about 70 degrees, not cold. Even after 20 minutes driving on the highway, the engine would still refuse to turn off at red lights. The energy display monitor at these red lights showed no energy being produced by the engine even though it was clearly on, it was just blank as it normally is during red lights. The only way I managed to get the engine to stop at a light is when I would press the EV mode button. However, as soon as I would turn it off, even if the car was still sitting still, the engine would kick back on. Any thoughts?
     
    #1 Anthony E, Jan 5, 2017
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,699
    48,946
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    welcome!
    how many miles on her? could be a degrading hybrid battery, or possibly a bad 12 volt.
     
    #2 bisco, Jan 5, 2017
  3. Anthony E

    Anthony E New Member

    Joined:
    Jan 5, 2017
    3
    0
    0
    Location:
    Orlando, FL
    Vehicle:
    2010 Prius
    Model:
    II
    159k about. Quite a lot for a 2010
     
    #3 Anthony E, Jan 5, 2017
  4. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,699
    48,946
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    yes. i'm surprised you don't have any dash lights on. is it the original 12v?
     
    #4 bisco, Jan 5, 2017
  5. Anthony E

    Anthony E New Member

    Joined:
    Jan 5, 2017
    3
    0
    0
    Location:
    Orlando, FL
    Vehicle:
    2010 Prius
    Model:
    II
    Nope, no dash lights on at all. I'm honestly not sure, I bought the car about 4 months ago. I believe I can find out though.
     
    #5 Anthony E, Jan 5, 2017
  6. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,673
    38,214
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Accidentally shifted into B (instead of D)? I think that keeps the engine running, not sure.
     
    #6 Mendel Leisk, Jan 5, 2017
    scona likes this.
  7. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

    Joined:
    Dec 4, 2014
    778
    514
    0
    Location:
    Outside Philly, PA
    Vehicle:
    2009 Prius
    Model:
    II
    +2 on having the 12 volt battery checked. The car may be trying to charge it continually.
     
    #7 ILuvMyPriusToo, Jan 5, 2017
    Montgomery likes this.
  8. glutaman

    glutaman Member

    Joined:
    Sep 18, 2016
    73
    26
    0
    Location:
    Dublin, Ireland
    Vehicle:
    2010 Prius
    Model:
    N/A
    But even with the ICE off, the traction battery will feed 14V to the 12V battery. So why would a bad 12V battery keep the ICE running?
     
    #8 glutaman, Jan 6, 2017
  9. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

    Joined:
    Dec 4, 2014
    778
    514
    0
    Location:
    Outside Philly, PA
    Vehicle:
    2009 Prius
    Model:
    II
    I don't know specifically how the ECU reacts to a low reading on the 12V, but folks consistently report long ICE cycles (and consequent hits to mpg) as a consequence. Maybe the computer tries to direct more current to the battery to charge it. It is a simple thing to check and rule in or out, so is a reasonable place to start - particularly if one doesn't know the history of the vehicle.
     
    #9 ILuvMyPriusToo, Jan 6, 2017
    Montgomery and glutaman like this.
  10. slewinson

    slewinson Junior Member

    Joined:
    Nov 1, 2016
    36
    30
    6
    Location:
    Australia
    Vehicle:
    2009 Prius
    Model:
    N/A
    Heater on defrost or cabin temp set way high? My wife has done it a few times.

    Simon
     
    #10 slewinson, Jan 6, 2017
  11. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,673
    38,214
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Ruled out by initial post:

     
    #11 Mendel Leisk, Jan 6, 2017
    glutaman likes this.
  12. RyanM

    RyanM Member

    Joined:
    Sep 30, 2005
    68
    40
    0
    Location:
    Wisconsin
    Vehicle:
    2010 Prius
    Model:
    III
    159k is not that much for a 7 year old car. About 22k per year. Just a bit above the national average.

    I have 235k on my 2010, but have seen a few over 300k (mostly used for professional driving).

    I have never used my car for professional driving. I have considered uber/lyft as a part time thing for side cash.
     
    #12 RyanM, Jan 11, 2017
  13. herqulees

    herqulees Junior Member

    Joined:
    May 6, 2014
    59
    24
    0
    Location:
    Tennessee
    Vehicle:
    2014 Prius
    Model:
    Two
    Well I'm interested in hearing why a Prius would do this. Our 2014 did the same thing a week or so ago to my fiancee. Yet the day I hop in it to see what's going on it has yet to do it again. She told me the engine would stay running the whole 50mile round trip drive to/from work, most of it being stop and go traffic, for multiple days. No heater, no defrost, Eco mode on since we bought the car. 50-60F. Will check the 12v battery with a load tester if the car starts acting up again.
     
    #13 herqulees, Jan 16, 2017
  14. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,699
    48,946
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    not sure about menders b mode theory in post #6, worth testing. i have never used b in 12 years, so don't know.
     
    #14 bisco, Jan 16, 2017
  15. ILuvMyPriusToo

    ILuvMyPriusToo Senior Member

    Joined:
    Dec 4, 2014
    778
    514
    0
    Location:
    Outside Philly, PA
    Vehicle:
    2009 Prius
    Model:
    II
    If so, the symptom would not repeat (unless shifted into B again!)
     
    #15 ILuvMyPriusToo, Jan 16, 2017
    fuzzy1 likes this.
(You must log in or sign up to post here.)