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2008 Prius no start unless 12v dis/reconnected

Discussion in 'Gen 2 Prius Main Forum' started by Brenscars, Apr 10, 2020.

  1. Brenscars

    Brenscars New Member

    Joined:
    Apr 2, 2020
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    Location:
    North Carolina
    Vehicle:
    2008 Prius
    Model:
    Base
    Mentioned in an earlier post that I was considering a purchase of an 08 Prius with a no start issue unless 12v battery is disconnected between restarts with power button. I purchased the car after all for a really good price. I used a recommended scan tool (Torque Pro) and no codes showed up however I was able to get red triangle and VSC lights to go out. I have done the HV battery test which includes "hyper" driving the car in drive with a/c on and charging it full with all green blocks and then proceeding in reverse with a very slow discharge down to one block left after 6-7 minutes. Used Dr, Prius app. to show battery temp as well as voltage and it was low 60's(It's 59 degrees F here currently). No dead cells blocks showed and all were within 15-17 volts a block. I am stumped and wondering if anyone has had symptoms like this and knows what to test next? P.S. I tried to load a version of Techstream but could never get it work because key provided was not legit.
     
    #1 Brenscars, Apr 10, 2020
  2. TMR-JWAP

    TMR-JWAP Senior Member

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    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    You have a HV isolation fault. P0AA6. There are 5 possible subcodes to help determine it's location. Most often, but not always, it's an electrolyte leak at the bottom of a HV Battery module, which has no affect on module voltages, at all.

    The P0AA6 is the ONLY code that will allow the car to continue to drive normally, but once the car is turned off, it will not allow it to go READY again......unless you disconnect the 12v battery for a minute. Then just repeat the cycle

    This was mentioned in your previous thread...………but maybe this will help
     

    Attached Files:

    #2 TMR-JWAP, Apr 10, 2020
    Last edited: Apr 10, 2020
    ydpplqbd likes this.
  3. edthefox5

    edthefox5 Senior Member

    Joined:
    Jul 25, 2007
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    Location:
    Clearwater, Florida
    Vehicle:
    2007 Prius
    Model:
    Two
    Yeah your battery is rotten.Lots of corrosion and a cracked cell or 2. if you look at the outside of the battery box sometimes you can see electrolyte leaking out of the case. There's been some reports of loud pops in the back and smoke with continued driving doing battery resets which is battery modules exploding.


    If you have the TOD its throwing lots of codes your just not harvesting them with your obd.

    I have one of these works great on my G2. Easy to setup. Full TIS. Just don't use it on a laptop you use for business.

    https://www.amazon.com/VXDIAG-Diagnose-Programming-Compatible-Version/dp/B078N34ZPW/ref=sr_1_2?dchild=1&keyw
    ords=vxdiag+toyota&qid=1586607902&sr=8-2
     
    #3 edthefox5, Apr 11, 2020
  4. Brenscars

    Brenscars New Member

    Joined:
    Apr 2, 2020
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    Location:
    North Carolina
    Vehicle:
    2008 Prius
    Model:
    Base
    Update! So, I finally dug into removing HV battery block. Yes, I removed orange safety plug as well as 12v terminals just to be extra safe. I took off top cover and at first everything looked clean, until I turned rear of battery pack (closest to rear seat) over. Then I could see where a leak has occurred among maybe 6 cells
     
    #4 Brenscars, Apr 13, 2020
  5. dolj

    dolj Senior Member

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    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    I hope you realize in this state the battery is not safe. It is still two (and up to) 115 V blocks, depending where you might touch it and create a circuit. The battery should be handled with linesman's insulated gloves (rated to at least 300 V) until you remove at least one side of the bus bars wearing said gloves and preferably insulated tools.

    Maybe you realize this, but for the sake of some noobies with limited electrical knowledge, I'm putting it out there.
     
    #5 dolj, Apr 14, 2020
    Last edited: Apr 14, 2020
    edthefox5 and Prodigyplace like this.
  6. edthefox5

    edthefox5 Senior Member

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    Location:
    Clearwater, Florida
    Vehicle:
    2007 Prius
    Model:
    Two
    If I was working on this battery I would tape up all the wrench and tool handles with electrical tape. No tool bare metal surfaces to short to.

    High voltage tools are dipped no metal showing. Lots of potential in that box.

    And always always wear protective eye glasses.
     
    #6 edthefox5, Apr 14, 2020
  7. qmanqman

    qmanqman Active Member

    Joined:
    Mar 29, 2020
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    Location:
    CO
    Vehicle:
    2007 Prius
    Model:
    One
    Wonder if he'll make it back
     
    #7 qmanqman, Apr 14, 2020
  8. Krissy Martinez

    Krissy Martinez New Member

    Joined:
    Oct 4, 2023
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    Location:
    san dimas
    Vehicle:
    2009 Prius
    Model:
    Base
    hey same thing happening to my car
     
    #8 Krissy Martinez, Oct 6, 2023
  9. ColoradoCrow

    ColoradoCrow Active Member

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    Location:
    Leawood, KS
    Vehicle:
    2008 Prius
    Model:
    I
    Yup. Time for a new cells or a complete new battery.
     
    #9 ColoradoCrow, Oct 7, 2023
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