Key Not Detected, assuming short

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by amtx, May 4, 2026 at 12:40 PM.

  1. amtx

    amtx New Member

    Joined:
    Monday
    5
    0
    0
    Location:
    texas
    Vehicle:
    2010 Prius
    Model:
    III
    2010 w/ 117k miles. Light comes on while car is running, not moving, in D or P, and a door closes from someone getting in/out. Have checked to ensure gate fully closed, replaced FOB battery. The 12V adapter in cig outlet is unchanged/unmoved for cell charging with same phone, only a cord was replaced. Assuming there is a short or loose wire because it happens with door closing. 12V battery is about a year old and no other electrical issues. Keys stay on flat part of accessory/storage area while driving.

    Is there any way to narrow this down to FOB vs car better before hitting the dealership?
     
    #1 amtx, May 4, 2026 at 12:40 PM
  2. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
    13,579
    2,450
    0
    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    Car ever been in a wreck or damaged there are antenna . That detect fobs. Fob's can go bad. You could have a locksmith scan you're immo system . Some of these newer scanners will pinpoint breaks antenna issues etc . Might be cheaper than the dealer you're going to drive it to the locksmith so no service call he just walks out his backdoor with the scanner
     
    #2 Tombukt2, May 5, 2026 at 1:29 PM
    amtx likes this.
  3. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    114,877
    52,526
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    maybe the door switch
     
    #3 bisco, May 5, 2026 at 6:14 PM
    amtx likes this.
  4. amtx

    amtx New Member

    Joined:
    Monday
    5
    0
    0
    Location:
    texas
    Vehicle:
    2010 Prius
    Model:
    III
    Thanks! Will look into this.
    Def no major damage. I'm the 2nd owner - I did check the carfax at dealer. Might have been minor accident + repairs....
     
    #4 amtx, May 5, 2026 at 7:58 PM
  5. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
    13,579
    2,450
    0
    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    Then I would try the passenger front door it has sensor too. I know both my front doors will unlock when I extend my hand to handle on all my SKS cars .
     
    #5 Tombukt2, May 5, 2026 at 10:23 PM
  6. Tombukt2

    Tombukt2 Senior Member

    Joined:
    Nov 29, 2020
    13,579
    2,450
    0
    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    Passenger door?
     
    #6 Tombukt2, May 6, 2026 at 9:38 AM
  7. amtx

    amtx New Member

    Joined:
    Monday
    5
    0
    0
    Location:
    texas
    Vehicle:
    2010 Prius
    Model:
    III
    It happens with front and rear doors after it starts. I wasn't clear on the initial description.
    Today it was fine at first and then started doing it again. Maybe the FOB was sitting slightly closer at first. Planning to go to a locksmith tomorrow to see if they can help troubleshoot.
     
    #7 amtx, May 6, 2026 at 4:53 PM
  8. AzusaPrius

    AzusaPrius Senior Member

    Joined:
    May 27, 2020
    2,248
    935
    0
    Location:
    California
    Vehicle:
    2010 Prius
    Model:
    IV
    Lol mine does this and did it today.

    I would say its a low battery in the FOB.

    If you just changed it, it can be a cheap no name brand and is losing its power quick.

    Non issue and you can keep driving.
     
    #8 AzusaPrius, May 8, 2026 at 1:39 AM
  9. Mendel Leisk

    Mendel Leisk MMX GEN III

    Joined:
    Oct 17, 2010
    61,142
    42,044
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    What light?
     
    #9 Mendel Leisk, May 8, 2026 at 12:12 PM
  10. AzusaPrius

    AzusaPrius Senior Member

    Joined:
    May 27, 2020
    2,248
    935
    0
    Location:
    California
    Vehicle:
    2010 Prius
    Model:
    IV
    Key Not Detected message "light"
     
    #10 AzusaPrius, May 8, 2026 at 12:52 PM
    amtx and Mendel Leisk like this.
  11. amtx

    amtx New Member

    Joined:
    Monday
    5
    0
    0
    Location:
    texas
    Vehicle:
    2010 Prius
    Model:
    III
    Additional info after I stopped by locksmith...FOB battery voltage is good. The key not detected did not come on while I was there. He checked the FOB for what they typically can and said it is fine.
    The only thought he had was that the physical location of the FOB might be making a difference:
    Further forward on the flat area next to accessory panel, the signal may be getting blocked by the center line arm just enough to trigger the light/alarm.
    For now, I am trying to relocate the FOB and see how that goes. Today, it seems to have worked by moving the FOB to the rear of the flat area.
     
    #11 amtx, May 8, 2026 at 6:40 PM
(You must log in or sign up to post here.)