2003 prius red triangle

Discussion in 'Generation 1 Prius Discussion' started by William s, Sep 19, 2025.

  1. William s

    William s Junior Member

    Joined:
    Sep 17, 2022
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    Location:
    Ann arbor michigan
    Vehicle:
    2003 Prius
    Model:
    Base
    So I was driving the other day..all was normal and red triangle came on and transmission acted like I was I was in neutral...pulled over..transmission started working normally so I drove home..not far. Don't have access to techstream. Came out a few hours later..auxiliary battery has less than 2 volts..
    Can a bad 12v battery cause thus and if so please explain?
     
  2. Brian1954

    Brian1954 Senior Member

    Joined:
    Jan 31, 2021
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    Location:
    South Central PA, USA
    Vehicle:
    2011 Prius
    Model:
    III
    Just like the thread you started back in April of this year, you need to get access to a capable scan tool to read the trouble codes that are triggering the red triangle. Until that is done, you will not know how to fix the problem with the car.
     
  3. Trombone

    Trombone Active Member

    Joined:
    Oct 26, 2019
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    Location:
    Allentown, Pennsylvania
    Vehicle:
    2002 Prius
    Model:
    N/A
    Sounds like what happened to my '02. In my case, cleaning the MAF sensor cured the problem. But your 12V is definitely cooked!