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MFD Dies, now traction battery troubles

Discussion in 'Gen 2 Prius Technical Discussion' started by TimmGleason, Jul 20, 2018.

  1. TimmGleason

    TimmGleason New Member

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    2007 Prius Touring. Bought 8 or so months ago with 104K on the odometer. Have put about 7K on it, mostly commuting 60 miles or so daily. Around the 20th of June, the MFD went dead. No lights, no sounds, no motorcar. Check all fuses, nothing. Find a junk yard replacement after about a week or so, maybe 10 days. Decide to pull the JBL disc changer radio also for something newer (JVC touchscreen headunit) and add a small subwoofer (8" JBL self contained powered).

    Replace the MFD first. Power up vehicle, everything looks good! Yay! Change out radio and install sub in rear on drivers side, side-panel just behind the seat. Connect everything, works great, sounds great.

    Now for the problems. Start the vehicle and drive maybe 1/4 mile, dash board lights come on crazy. Red triangle, check engine, VSC, & brake system warning. Pull out OBD reader and fired up Torque. P0A80, battery failure. Get the 'Dr Prius' app and start looking at the individual blocks, and block 6 is much lower than all the others, consistently. Run the chicken dance Battery Life Test and get result of 20% life left, replace soon. Pull the trim panels in the rear to access the traction battery, see that it has already been replaced previously with a Dorman. Re-manufacture date- June 2015, exactly three years prior to now.

    Order two replacement cells from eBay, and when they come in, they measure 7.94 and 7.91. Pull traction battery and start testing cell voltages. Most are 7.80 to 7.84, couple are 7.91 (Block1), and #11 is 6.54. Block 6 just like observed. Replace #11 and #12 with eBay cells, reassemble, and re-install. I have no particular way of balancing all the cells out, so I am just trusting to luck here. Run Life Test again, 50%. Pretty good, 30% jump. I'll take it.

    However...

    Now the vehicle codes EVERY time I drive it. Sometimes it's 100 feet, sometimes it's 5 miles. If the car has been sitting for longer than 15 minutes, it will code (P0A80) and immediately discharge the battery stores down to 15-20% charge. Reset it and it's fine for the rest of the drive.

    Aux battery has a consistent 13.8 - 14.1 volt reading on it while sitting.

    Kind of resigned at this point to replacing the traction battery with a new one, but I am wondering if there is something else I might have missed here (thus the lengthy story-telling)?

    Cheers!
     
  2. bisco

    bisco cookie crumbler

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    you are not testing the 12v correctly.
     
  3. JC91006

    JC91006 Senior Member

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    You might still have a warranty with Dorman, the battery is not sold immediately after it's manufactured. I'm really surprised that battery lasted 3 years.

    As for your situation, you still have bad modules in the battery pack. If you read the codes, it'll provide you with the information with which block is low. So read the codes again
     
  4. TimmGleason

    TimmGleason New Member

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    Not sure how to respond to this. I was unaware that there is a correct and an incorrect way to use a volt meter.
     
  5. TimmGleason

    TimmGleason New Member

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    I was unaware that the traction battery had been replaced when I purchased the vehicle last October. There were extensive service records from the vehicles original owner (I an the second owner), but no mention of battery replacement. I imagine that now that I have opened said battery and replaced several cells that there is less chance of that warranty being honored.

    The only code that the vehicle has ever posted is the P0A80 general battery failure, so I am unsure which code you are suggesting I read again. Did you perhaps mean RE check the cell voltages?

    Thanks!
     
  6. bisco

    bisco cookie crumbler

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    you are using the volt meter correctly, but testing the battery while it is being charged by the converter is almost pointless.
     
  7. TimmGleason

    TimmGleason New Member

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    Well yes, that does make complete sense when actually explained instead of just being told "you're doing it wrong".
    Thank you.
     
  8. JC91006

    JC91006 Senior Member

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    You are using a code reader that is not reading all the prius codes. Something more advanced is needed. P0A80 should be followed by a code, example P3014 telling you the block that actually triggering the P0A80 code.

    A less scientific way of identifying bad modules would usually require you to test the battery for an entire week and then take voltage measurements. The bad modules will usually self discharge to a level you can identify that's not similar to the other modules

     
    #8 JC91006, Jul 23, 2018
    Last edited: Jul 23, 2018
  9. TimmGleason

    TimmGleason New Member

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    Should I be able to read those with the Techstream software and the mini vci cable? I have those but have not tinkered with it too much yet.

    Thank you
     
  10. fotomoto

    fotomoto Senior Member

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    Yes, it will show you the voltages of each of the 28 blocks of modules so you can see if there are others about to die too.