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HV CPU failure symptoms

Discussion in 'Generation 1 Prius Discussion' started by John B., Nov 15, 2016.

  1. John B.

    John B. Junior Member

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    I have a 2003 Prius that I am trying to bring back to life. I have changed several cells in the HV battery, but I still keep getting the 3006 error code. It appears that the batteries are in range to me, so I am wondering if the CPU is failing. Besides the 3006 error, I have had one for the ecu a couple times. In addition when driving the car the battery status in the car seems to fluctuate wildly. It will say it is fully charged one minute, and then I will go a couple blocks and it will be at the low range. In also, it seem like it takes a really long time for the car to get into the ready state and start. Maybe 4-5 times as long as the 01 prius I have. The other warning codes I get are for certain blocks registering too low. The problem is that the weak cell set is always a different set of batteries.
     
    #1 John B., Nov 15, 2016
  2. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

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    It sounds like you have more bad cells to me. The symptoms you describe are a weak cell(s). If the car sat for a long time, you will likely have multiple weak cells.

    A great way to check would be to place the battery from your working 01 into the 03.
     
    #2 usnavystgc, Nov 16, 2016
  3. dolj

    dolj Senior Member

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    The consensus of opinion (from people who refurb packs for a living) is that the availability of good cells for Gen I are pretty much non-existent now, so just buy a new pack from Toyota which will have genuine new cells in it. You may want to try refurbing using cells from two good Gen II or Gen III packs, as you will need to replace all 38 modules (can't mix 'n match Gen I, II and III). However, the cost by the time you are finished would be so close to a new Gen I pack from Toyota, that you may as well just do that.
     
    #3 dolj, Nov 16, 2016
    strawbrad and usnavystgc like this.
  4. Kevin_Denver

    Kevin_Denver Active Member

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    Have you tested the amp hours of each module and performed a load test on each to determine that the voltage drop is near uniform for each module under load? It sounds like you have bad modules, they're just showing acceptable voltages when not under load (and this voltage doesn't tell half the whole story). It sounds like your pack needs a full reconditioning, where each module is charged and discharged 3+ times and the amp hours recorded each time it's discharged. Then bad modules are replaced with good ones.

    I'm not ruling out a bad ECU, but considering the battery is 13+ years old, the battery is where I'd look first. Have you looked through the battery reconditioning threads on Prius Chat? The discussions for the gen 2 are just as relevant for the gen 1; it just has more cells.
     
    #4 Kevin_Denver, Nov 17, 2016
    Last edited: Nov 17, 2016
    FireFighterHill and strawbrad like this.
  5. FireFighterHill

    FireFighterHill Member

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    My advice is to get a Bluetooth OBDII reader and the TORQUE app. configure the app to see all the module pairs and log the info. You should be able to see rather quickly which pair/pairs of modules are out of range and need to possible be replaced. Your problem could also be as simple as corroded bus bars or corroded and deteriorated sensing harness. The cheapest way to cycle the modules is with an hobbyist RC battery charger, but very time consuming. There are LOTS of threads on this. I was able to learn enough to test and rebuild my battery pack all from the information found in this forum.
     
    #5 FireFighterHill, Nov 27, 2016
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