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P3000, P0A80, and a complicated history

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by AeronautMitch, Jan 30, 2023.

  1. AeronautMitch

    AeronautMitch New Member

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    2004 Prius
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    I
    I have a 2004 Prius with 171k miles that has been performing well, but recently the 12v battery died. Shortly after, some events transpired recently that have my head scratching.

    Before replacing the 12v, I had jumped the car a couple times to get it to turn on so I could read codes. During one of those jumps, I had an extremely embarrassing and expensive brain fart - I jumped the car backwards (embarrassing since I'm fairly experienced working with basic electronics). It popped the 150 fuse block and two others, a 10amp and a 15amp. I had the dealership replace all three, then I replaced the 12v battery myself after driving it home. After installing the new 12v, the car drives fine, but now I'm getting the red triangle and codes P3000 and P0A80. First it was just P3000 and triangle but after a 40min trip today P0A80 popped up too.
    These are totally new after putting the new 12v in; at the shop and during my 5min drive home from the dealership the car was code free. During that trip home I had the old 12v in; they had jumped it before I left.

    The 12v battery install was uneventful, no problems getting the HV battery vent reinstalled. My 2004 isn't smartkey enabled, so I bought a 34B20R-AGM by Duralast which should be fine from what I've read.

    I bought my Prius used and in excellent shape 100k miles ago and to my knowledge has the original HV battery but still gets great gas mileage for how old it is, averaging 40-46mpg on the highway, about 35-40 in town. Please pardon the dumb questions but, could jumping it backwards have damaged the HV battery? It seems like it shouldn't, and The car was sitting for 4 or 5 days while waiting on my 12v to be delivered, but I've done that before without problems. Could putting a new 12v in trigger it? I tested the voltage before putting it in and it was healthy and does its job now that it's in the car. Maybe just a coincidence? The shop gave my car an all green health report after a multipoint inspection.

    I used Dr. Prius to collect some data before, during, and after the trip today. I was ok with driving it today for my 40min to work since the temps seemed ok, getting no higher than 65F, it held a good charge and performed well, giving mpg on the highway averaging 45mpg. I'm not familiar with the app, but while the battery wasn't being charged or under load, the number 5 block seems to consistently drop down...judging from the bar graph.

    I don't plan on driving it in this state for very long in case doing so could harm the car, but I need to find out what's wrong so I can decide what I want to do. I can see if I can provide a more detailed report or any other info you'd like on the car. I saved a recorded a CSV file of the trip today but haven't poured over it, just took some screenshots of Dr. Prius during the drive.

    Thanks for taking the time to read this!
     

    Attached Files:

  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!
    You may have a HV ECU or harness/plug with some corrosion, or it could be a failing/unbalanced cell in one of the block #5 modules.
    Take a picture "under load"; while "heavily" charging (hard braking) or discharging, this will show the true state of the graphed outlier(s).

    If you have basic tools and a DIY mindset, check for corrosion in the HV sense wires/connector and HV battery ECU.

    Given the miles, consider reconditioning/balancing your HV battery with a "HV power supply" or a "grid charger", it may or not help to fix it.
    Though not a fix for the current issue, did you have a chance to clean up the HV battery fan while replacing the 12v battery?

    FYI : you're moderated until you've posted 5 times.
     
  3. dolj

    dolj Senior Member

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    You are correct, no it wouldn't have damaged the HV battery.
    No, the 12 V wouldn't trigger anything in the HV battery by simply just replacing the 12 V battery so, yes, it is exactly that coincidence.

    If you are up for it, SFO's suggestion is a good one or if you just want it to be done once so you can forget about battery issues, then just get a new OEM battery installed. You could self-install to save the labor if you wish.
     
    #3 dolj, Feb 7, 2023
    Last edited: Feb 8, 2023
  4. ChapmanF

    ChapmanF Senior Member

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    * wouldn't
     
  5. dolj

    dolj Senior Member

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    Thanks, Chap for spotting that typo. I've made the edit to correct it.