2008 Prius With Bad "Battery ECU and HV ECU" - Help, Please

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Prius Newby, Apr 30, 2024.

  1. Prius Newby

    Prius Newby Junior Member

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    My sister owns a 2008 Prius with 190K miles.

    She bought it about 4 months ago. The previous owner claimed he replaced the hybrid battery, and we believe him even now...

    She drove the car about 5K miles since buying it without a significant issue. Fairly recently, the red triangle of death light illuminated on the dash, and the hybrid battery cooling fan (the fan that is vented near the passenger side of the back seat) began intermittently blowing air. The car was running fine.

    So, she took the car to the local Toyota dealership for diagnosis. The dealership results are attached. Apparently the Battery ECU and HV ECU may be faulty. The dealership cleared the codes, and the car was fine for the next ~500 miles, then the red triangle of death light illuminated and hybrid battery fan began blowing again.

    Obviously, the $3,000 price tag for replacing the two ECUs is really high, so I have looked into getting salvage yard ECUs, and the total would only be about $200 for both ECUs. My understanding is once installed, a Toyota dealership must re-program the ECUs. Is this correct?

    Any and all assistance is appreciated!
     

    Attached Files:

    #1 Prius Newby, Apr 30, 2024
  2. bisco

    bisco cookie crumbler

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    could just be corrosion at the ecu pins and harness connector. open up the battery and look around. that's an opportunity to confirm a new battery as well.
    high voltage! read up on precautions necessary.
     
    #2 bisco, Apr 30, 2024
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    Well, IF the Hybrid Control ecu is replaced, you need to perform a "handshake" procedure with the other ecu's on the car. This requires an OE level scantool.

    The HV battery ecu is plug & play.

    I might want to see some more information before replacing things. The mentioned TSB states that there should be several specific codes in the battery ecu. The write up only mentions the P3000, which is set by the Hybrid Control ecu - it means "hey the HV battery ecu says it has a problem - go there and look for codes". There's nothing in the write up about any battery codes.

    Maybe the P3000 freezeframe data does match the TSB, or maybe not.

    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Apr 30, 2024
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  4. TMR-JWAP

    TMR-JWAP Senior Member

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    95% chance it's just an HV battery issue. 4% chance it's something else in the hybrid system, 1% chance the dealership actually understands what they're looking at in this case and is being straight with you.

    Please look at this thread, sounds like a VERY SIMILAR situation

    Does the "hybrid control computer" go by another name? | PriusChat
     
    #4 TMR-JWAP, May 1, 2024
  5. Prius Newby

    Prius Newby Junior Member

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    I looked at the thread and am unsure what to do next...

    Okay, I will recommend she call the dealership and ask for any and all codes, thanks.
     
    #5 Prius Newby, May 1, 2024
    Last edited by a moderator: May 1, 2024
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  6. Carall

    Carall Member

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    These symptoms indicate a problem with the hybrid battery; it appears to have been reconditioned and poorly reconditioned.
     
    #6 Carall, May 1, 2024
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  7. maleko

    maleko Member

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    any updates? dealing with similar on mine, not exact. just brainstorming my dilemma
     
    #7 maleko, Jun 19, 2024
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