help me solve this please! 07 HV battery

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jason99, Sep 17, 2021.

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  1. Jason99

    Jason99 New Member

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    2007 Prius
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    ----USA----
    So I have had a terrible time trying to figure out what is wrong with my 2007 Toyota Prius. The problem started when I drove it after having been parked for 3 weeks, I started it and received the red triangle of death along with the (!) light and VSC light. after doing some research I assumed that the 12V battery had just gone bad as it was original with 250,000miles on it. So I promptly bought a new one, nothing changed. then I read the codes on an OBD II and receive a P0A80 error (faulty HV battery right?) well I take the whole thing out and open up the case, clean the little corrosion there was and wire brush the bus bars hook everything back up, install and... nothing new. Then I find that a connector near the HV battery fan is corroded pretty bad so I replace that... nothing. At this point, I give up on trying to figure it out myself so I bring it into my local Toyota dealership and am told that the HV battery and HV battery ECU need to be replaced and they will do it for 4K. I was able to find one at a local junkyard for less than a quarter of the cost and swapped them completely, still same lights and now the code is reading P3030.

    please help me figure out what is wrong.
     
    #1 Jason99, Sep 17, 2021
  2. TMR-JWAP

    TMR-JWAP Senior Member

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    Your first issue was just due to the age of the battery and sitting for 3 weeks unused.

    The HV battery is built using 28 individual modules. The ecu monitors these modules for abnormal conditions like low voltage so it can provide warning if anything abnormal is going on. Over time, some of the 28 modules will develop self discharge characteristics, which will bleed off some of that modules charge. If you use the car frequently, it's not really noticeable. Kind of like refilling a cup of coffee after every sip. If the car sits a long time, that self discharge may cause the module to so low that it now triggers that warning. That's what happened to you. Sometimes this can be resolved by 'force charging' the HV battery by running the engine to charge the battery back up, which puts in back into the state it was prior to the extended shutdown.

    Now, since you already swapped the battery, the force charge is no longer an option for you. Now you have a used battery that has additional problems. A P3030 means the wire harness that the ecu uses to monitor the modules has a broken connection somewhere. The 28 modules are monitored in sets of two. Each set is called a block, so there are 14 blocks in your battery. Each block has a sensor wire that goes to the ecu. Typically, where the wire mounts to the module terminal, there is some corrosion that will weaken the crimp connection. Sometimes it's bad enough the crimp connection may crack and the wire falls off. That is what usually gives the P3030. All those sensor wires plug into the ecu using one plug/socket. Sometimes that plug/socket will develop corrosion on a few of the pins, and it may get bad enough that the pin breaks off. This will also give a P3030.
     
    #2 TMR-JWAP, Sep 17, 2021
    Last edited: Sep 17, 2021
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  3. OBJUAN

    OBJUAN Member

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    Opportunity to rebuild you pack.. TMR-JWAP is a pro! You will notice the corrosion starts on the negative post and spreads. Batts are leaking electrolyte. If the corrosion is bad enough getting in to the ECU sense connector, can trigger a fire as there are no current limiters between the sense wires. good luck
     

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    #3 OBJUAN, Sep 17, 2021
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