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Techstream shows block voltages go to zero momentarily

Discussion in 'Gen 3 Prius Technical Discussion' started by Hhumber, Mar 1, 2021.

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  1. Hhumber

    Hhumber Junior Member

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    Vehicle:
    2011 Prius
    Model:
    XLE
    I just finished reinstalling the hybrid battery in my new to me 2011 Prius. Techstream shows that block 1 and 2 momentarily go to 0.00 Volts then back to around 15V. It is throwing a P0AA6, a P0B47, and P3020. The P3020 is only a permanent code so I believe will go away after driving. If I record the voltages of the blocks while driving, all the voltages are pretty consistent, but Block 1 and 2 sometimes go straight to zero and then shoot back up.
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    The other codes are both permanent and current. I am thinking this means the voltage sensor harness is shorting out or the voltage regulator connector has burnt up. Are there any other causes for this?
     

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    #1 Hhumber, Mar 1, 2021
  2. Hhumber

    Hhumber Junior Member

    Joined:
    Feb 11, 2021
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    Location:
    Durham, NC
    Vehicle:
    2011 Prius
    Model:
    XLE
    I went ahead and took the battery voltage sensor off the battery and the connector behind the connector are burnt off. What could have caused this?
     

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    #2 Hhumber, Mar 1, 2021
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  3. PriusCamper

    PriusCamper Senior Member

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    Vehicle:
    2007 Prius
    Model:
    Two
    Always great to see someone so quickly diagnose this very common problem... For some reason the corrosion gets into the voltage sensing plug socket and if the corrosion doesn't get cleaned out it short circuits and burns the ECU. This is so common that used ECUs that used to sell for $50 now are hard to find for less than $100 and as always the Toyota Stealerships make sure they're consistent and reliable when it comes to ripping people off by charging $800 for a new one.
     
    #3 PriusCamper, Mar 1, 2021
  4. Hhumber

    Hhumber Junior Member

    Joined:
    Feb 11, 2021
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    12
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    Location:
    Durham, NC
    Vehicle:
    2011 Prius
    Model:
    XLE
    I went ahead an ordered a used ECU and wiring harness because mine showed small amounts of heat damage in the ecu plug. The battery pack had been worked on so I think this may have been a long-standing issue. Are there any other places I should look that could have caused this so it doesn't happen again?

    As far as the ecu, could covering the ecu leads behind the socket in resin or epoxy keep this from happening?
     
    #4 Hhumber, Mar 1, 2021
  5. PriusCamper

    PriusCamper Senior Member

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    Vehicle:
    2007 Prius
    Model:
    Two
    Build a spreadsheet of your modules with their voltage numbers and there's a chart on here so you can identify date of manufacture of each module based on their serial numbers to figure out if any of them are not original. Also connect a 50w 12v halogen bulb to the module and record the voltage loss at the end of 2 minutes before you disconnect the bulb.

    And let us know if you want to charge up modules with a hobby charger so you can do reconditioning and self-discharge testing and we can walk you through that.
     
    #5 PriusCamper, Mar 1, 2021
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