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P0A80 - Three HV blocks showing +323 to -300 volts!

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by MB78732, Oct 2, 2021.

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  1. MB78732

    MB78732 Junior Member

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    I have a rebuilt battery pack in my 2008 Gen2, 175,000mi. I periodically look at the 14 HV blocks using Torque Pro, and hi/lo voltage usually runs between 14.5v-19.0v. So...today I get the red triangle of death, do a scan and it's P0A80. I fire up Torque pro and one cell shows a high value of 323.9v, and two show a low value of around -300v. That would explain a P0A80, but I can't believe those cell readings. As I drive around town running errands the cells usually read within the expected range. But occasionally one or more will throw a crazy voltage value like this.

    I don't know what reports these cell values, but I'm wondering if it's not the cells but some other electronic gizmo that's failing and giving spurious voltage data. Any thoughts/wisdom?

    Thanks,
    m-
     

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    #1 MB78732, Oct 2, 2021
  2. Travis Decker

    Travis Decker Active Member

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    check for corrosion on frame wire harness to battery ECU. see it all the time. remove plug inspect pins on ecu
     
    #2 Travis Decker, Oct 2, 2021
    SFO likes this.
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    +1 to having a fault with the voltage sense wires to the battery ecu - if it was just one block going wierd then it might be a broken wire, if multiple blocks are wonky then it is more likely that the connector and ecu are damaged by corrosion. If so you can get "wire frame #2" from Toyota for a reasonable price and another ecu off ebay (or a local salvage yard) .

    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Oct 2, 2021
  4. MB78732

    MB78732 Junior Member

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    Thanks @Travis Decker and @mr_guy_mann. Is there a step-by-step of this somewhere? I've watched the HV battery unit as a whole be swapped out twice, but assume the battery ECU is inside the big aluminum case. I don't want to go in there blindly. Thanks.
     
    #4 MB78732, Oct 3, 2021
  5. Travis Decker

    Travis Decker Active Member

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    take cover off drivers side you will see ECU unplug look at connection
     
    #5 Travis Decker, Oct 3, 2021
  6. dolj

    dolj Senior Member

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    ... If you find the plug is badly damaged and therefore will need replacing, then you will need to take the cover off the rest of the battery in order to do that.

    You should find plenty of videos on YouTube that covers all that and more. Probably many threads here as well.
     
    #6 dolj, Oct 4, 2021
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