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Bad cell replaced then P3030 code

Discussion in 'Gen 2 Prius Technical Discussion' started by mlduncan96, Mar 30, 2020.

  1. mlduncan96

    mlduncan96 New Member

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    Okay, I just replaced a bad cell in my hybrid pack. This is about the 5th or 6th cell I have changed out. I have come across a few other issues with the hybrid pack, but really scratching my head and banging it against the wall tonight.

    The last few times I have noticed the oxidizing and corrosion more significantly on my copper bus bars. Today I sanded them all clean and gave a small coating of dielectric, first time trying this, to prevent the oxidizing of the copper bus bars. The corrosion and oxidizing has created problems in the past where my cells were all good but had the reading of a bad cell until I cleaned and reinstalled the bars.

    So, after putting it back together the codes would not reset. They triggered as soon as I reset them. I then noticed the code was new. Looked it up and saw it was typically a broken wire on the monitor. I went back in and checked continuity on every wire and it was good. reconnected the electrical and still have the same code.

    So, is my dielectric grease the culprit or am I missing something else? Side note: I did not clean the sensor plates, just the copper.

    Thank you for any help or advice.

    Matt
     
  2. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    It's not the dielectric grease. You just have not managed to pin point the broken voltage sensing wire.
    What are you using to read codes and can you see the 14 block voltages with your reader? The block voltages would show which sensing wire is broken.

    Did you pull the orange voltage sensing wire plug from the battery ECU? Corrosion can form at that plug and cause the P3030 code.
     
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  3. mlduncan96

    mlduncan96 New Member

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    I am using Torque Pro. I am going to look up and add the PIDs to read the actual voltages this morning.

    I did pull the orange sensing wire plug. It looked good, with nothing appearing burned or corroded. I figured any light corrosion would be displaced, at least temporarily, with disconnecting and reconnecting. I used my volt meter to monitor continuity between the back side of the connector and the nut where the wire attaches.

    Matt
     
  4. mlduncan96

    mlduncan96 New Member

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    Okay, I isolated the issue to bank 5. Looking at the raw data, the bank is flipping back and forth from +16V to -16V. I was expecting to see no reading with a bad wire. What can cause the voltage reading to flip back and forth between positive and negative? Is this an issue within the ECU?

    Thanks,
    Matt
     
  5. mlduncan96

    mlduncan96 New Member

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    Problem solved!! After pulling some of the sensing wires, cleaning the ends and confirming continuity I found the problem on the other side. I had managed to miss tightening one nut. So, nut tightened and code is gone! Thank you!
     
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  6. George W

    George W Active Member

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    Now you know!! :)
     
  7. TMR-JWAP

    TMR-JWAP Senior Member

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    If you'd like to plan ahead for next time, order a new 'wire frame #2' from Toyota to replace the voltage sensor wire harness. It comes complete with new busbars. Runs about $57 bucks. It makes life much easier and is a ton more reliable.
     
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  8. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    That is what happens with a P3030 code. After a couple of minutes of the voltage flipping positive to negative one block will read about 32 volts and the other will read zero.

    The voltage wire sensing plug is orange because there is full pack voltage present. It deserves respect and caution. I recommend removing all the bus bars before messing with that plug.

    Glad to see you got it fixed.
     
  9. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    While I'm on my soapbox preaching battery safety here's an example of what can happen when bus bars nuts are not properly tightened.

    Battery Fire | PriusChat