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P3020 returns

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by mike_az_21, Aug 21, 2023.

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  1. mike_az_21

    mike_az_21 New Member

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    So, this was purchased as a project since day one.

    It had two fault codes when bought -420(catalytic converter) & a P0A93 - for the inverter pump

    swapped the pump, sold the oem converter before it got stolen & got a cheap aftermarket


    Sometimes the 420 still comes back, which is understandable since I’m using a 57 dollar unit off eBay

    Then after about a week of driving without any probs the p3020 pops up. I cleared it - still gets amazing mpg, runs excellent. The car has zero leaks, was mostly garage kept, all maintenance was done by a dealer. The car is a 2007 Touring with almost 290k, battery was last “redone” about 5 years ago.

    Throughout driving for a week, it popped again about 3x.

    I pull the battery, triple check everything. Founds quite a bit of corrosion. Cleaned everything, load tested every cell - lowest I got one to drop to was 7.49v - some were 7.6 or so, and quite a few 7.7’s

    All back together, again - drives perfect, now seems to charge way quicker. But, out of nowhere - p3020

    Any other input would be appreciated, only thing I’m left with is replacing the battery computer. But, I hate throwing parts at cars.
     
    #1 mike_az_21, Aug 21, 2023
  2. mike_az_21

    mike_az_21 New Member

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    Also to add, when the code pops the car starts running “odd” - it starts pulling all the power from the battery & not recharging - until I clear the code.

    So, I just roll around with a scanner plugged in
     
    #2 mike_az_21, Aug 21, 2023
  3. PriusCamper

    PriusCamper Senior Member

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    Go to Google and do a search that looks like this and start reading:

    upload_2023-8-21_13-17-34.png
     
    #3 PriusCamper, Aug 21, 2023
  4. mike_az_21

    mike_az_21 New Member

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    Thank you for your reply! It helps in no way possible as the thread that I read days ago.
     
    #4 mike_az_21, Aug 21, 2023
  5. Brian1954

    Brian1954 Senior Member

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    The trouble code from the car, P3020, is telling you what is wrong with the HV battery. Replace one or both of the moduls in block #10 and see what happens OR replace the complete HV battery pack.

    Five years since the HV battery was "redone" is very good. Usually it is a few months to 2 or 3 years until you have problems.

    Posted via the PriusChat mobile app.
     
    #5 Brian1954, Aug 21, 2023
    Last edited: Aug 21, 2023
  6. mike_az_21

    mike_az_21 New Member

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    Even if it tests completely fine?
     
    #6 mike_az_21, Aug 21, 2023
  7. dolj

    dolj Senior Member

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    It depends on how you're testing them. You assume we know what you did when you say you did a load test. Was the 7.49 V module one of the ones in block #10 perchance?
     
    #7 dolj, Aug 21, 2023
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  8. Brian1954

    Brian1954 Senior Member

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    Do you have an OBD2 bluetooth adapter that works with the Dr. Prius app? If not, you should buy one and monitor the voltage difference between the battery blocks during hard acceleration ( high amperage discharge ) and maximum regenerative braking ( high amperage charging). This stress on the modules will create a larger than 0.30v difference between the battery blocks and will trigger the trouble code that you have.

    Posted via the PriusChat mobile app.
     
    #8 Brian1954, Aug 21, 2023
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  9. mike_az_21

    mike_az_21 New Member

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    Negative, the 10 block checked out completely fine at about 7.68-7.69

    I made a “load tester” with a light bulb & my DVOM - I thought I nailed it, when I found the the lowest one. But, it wasn’t in the ten block.
     
    #9 mike_az_21, Aug 21, 2023
  10. mike_az_21

    mike_az_21 New Member

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    I just came across that actually

    But, I swear I had it when I seen and cleaned down all the corrosion + the cells checked out

    I had my mechanic friend get on it today with his Solus - and, it’s throwing out ABS codes - yet, he couldn’t spot anything on the battery. He refuses to work on these. Lol - he does all my diesel & heavy line work
     
    #10 mike_az_21, Aug 21, 2023
  11. TMR-JWAP

    TMR-JWAP Senior Member

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    The car is telling you where the problem lies, but you're not believing it........
    block 10 is the 19th and 20th module from the non-ecu end of the battery pack.
    Voltage checks and small load testing do not always reveal the answer.

    Take a look at this thread starting around post 15
    Just Another HV Battery Thread and Experiments | PriusChat
     
    #11 TMR-JWAP, Aug 21, 2023
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  12. rjparker

    rjparker Tu Humilde Sirviente

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    Cliff Notes:

    Battery voltage and amp capacity do not always correlate particularly when the problem is more than a discharged cell.

    Rechargeable batteries have a limited number of cycles available. If this was not true there would be built in reconditioning circuits.

    Some modules fail before others providing an opportunity for those who mix and match.

    Eight or more years of reliability requires new cells.
     
    #12 rjparker, Aug 22, 2023
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  13. mike_az_21

    mike_az_21 New Member

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    I have looked up the codes - but, I really thought the corrosion would have been the culprit - especially after load testing the cells

    I was expecting to find crappy cells in the 10 spot - but, they checked out fine - not even the lowest ones

    it’s still an interesting running project atm - still gets great MPG, but I really expected the code not to come back after cleaning all of the copper & cell connections
     
    #13 mike_az_21, Aug 22, 2023
  14. dolj

    dolj Senior Member

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    And the "10 spot" is as in the image below?

    Prius Gen II HV Battery module ID.png
     
    #14 dolj, Aug 22, 2023
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  15. Tombukt2

    Tombukt2 Senior Member

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    A lot of times those 10 spot wires if you unbolt them off of the battery flip them over and look at the side that's aiming towards the battery and you'll see green corrosion and one of those wires will be not copper it will be black like it's seen lots of heat black blue whatever I have those wires many sets laying right here in the carport when I test the wires from end to end with an ohm meter etc or so on and so forth they seem to tell me that the own meter which is a high-end model is getting good readings continuity is good electricity is flowing through the wire seemingly okay but that's what I see .. maybe this can be partially some of the resistance and issue I don't know I'm not really a battery person per se but I do know that in other electrical things that I do seeing wires that are blue black as generally not a good thing I need to go look at heating elements and things that are in that circuit to see what is drawing the high amp or high current load a bad heating element something along those lines so I imagining the car's battery and the orange wiring I or we wouldn't want to see blue black copper I would think.
     
    #15 Tombukt2, Aug 22, 2023
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  16. Brian1954

    Brian1954 Senior Member

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    There are 28 modules in your HV battery pack. Toyota groups two modules together to create a block. Toyota uses small wires on each block to monitor the voltage of the block. If the voltage difference between the 14 blocks in your battery pack becomes too large, a trouble code is triggered by the ECU.

    Trouble code P3020 is telling you that one or both modules that make up block #10 are bad. I do not think that you understand where block #10 is located in your battery pack and that there are two modules that make a block.
    Posted via the PriusChat mobile app.
     
    #16 Brian1954, Aug 22, 2023
    Last edited: Aug 22, 2023
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  17. mike_az_21

    mike_az_21 New Member

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    Yup, I focused on the wrong blocks. I was counting them backwards.

    I’ll see how she goes - I’m not in the mood to tear it back down again right now.

    But, yeah - I did not really focus on the chrome tabs & that can def be the issue
     
    #17 mike_az_21, Aug 22, 2023
  18. mike_az_21

    mike_az_21 New Member

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    Tore it all down - boy, u sure get faster after your 1st run

    Looked at the 10 block & connectors - nothing. Checked the wires running to the battery ECU - nothing
    D4A5524A-FB70-4A17-919E-5AA6C59E0E37.jpeg
     
    #18 mike_az_21, Aug 22, 2023
  19. Brian1954

    Brian1954 Senior Member

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    You are not going to see an internal problem with the two modules in block #10 by looking at the outside of the modules unless the module is leaking electrolyte. One or both of the two modules that make up block #10 are bad internally and need to be replaced.

    You can monitor the voltage of block #10 and compare it with the other 13 blocks by using an app like Dr. Prius or other app like I suggested in post #8 above.

    Also, look at post #11 above again.

    Posted via the PriusChat mobile app.
     
    #19 Brian1954, Aug 22, 2023
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  20. mike_az_21

    mike_az_21 New Member

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    I’m waiting for my Amazon Bluetooth dongle to get here & go from there

    Load tested them again & the voltage held well.
     
    #20 mike_az_21, Aug 22, 2023
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