1. Attachments are working again! Check out this thread for more details and to report any other bugs.

06 traction battery voltage jumping

Discussion in 'Gen 2 Prius Technical Discussion' started by Duramaxjoe, Oct 28, 2016.

  1. Duramaxjoe

    Duramaxjoe New Member

    Joined:
    Oct 28, 2016
    1
    1
    0
    Location:
    Ky
    Vehicle:
    2006 Prius
    Model:
    ----USA----
    image.png image.png I've rebuild a couple of these gen 2 batteries and never ran into any issues. This time after reinstalling the traction battery I got code p0afa hybrid battery system low voltage. And the car will not start. I downloaded torque and 13 of 14 read around 15.4v but block 14 jumps back and forth from positive 15.2 to negative 15.1. I have no idea what could cause this or what my problem could be. Thanks in advance
     
    #1 Duramaxjoe, Oct 28, 2016
    mydaughtersprius likes this.
  2. jadziasman

    jadziasman Prius owner emeritus

    Joined:
    Jan 17, 2011
    1,355
    487
    0
    Location:
    District 6
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    The P0AFA could be caused by a problem in the battery ECU or the bus bar assembly according to the service manual. It offers little troubleshooting help beyond that.

    My best guess is that the sensor wiring at block 14 is loose/damaged and does not have the proper continuity to the battery ECU. You will need to take the cover off the HV battery so you can inspect/test the sensor wiring at block 14.

    It is also possible that the bus bar wiring harness connector at the battery ECU is damaged. You should have noticed that if/when you disconnected the harness (not everyone disconnects the harness from the ECU when rebuilding).
     
    #2 jadziasman, Oct 29, 2016
  3. DanGiant

    DanGiant Junior Member

    Joined:
    Jan 19, 2015
    12
    6
    0
    Location:
    Bremerton
    Vehicle:
    2005 Prius
    Model:
    Two
    Slightly off topic, but how did you get torque to show the individual cell voltages? I would like to set my torque profile to do the same.

    SAMSUNG-SM-T817A ?
     
    #3 DanGiant, Nov 30, 2016
  4. strawbrad

    strawbrad http://minnesotahybridbatteries.com

    Joined:
    Aug 9, 2011
    953
    1,002
    0
    Location:
    Minnesota
    Vehicle:
    2005 Prius
    Model:
    II
    The cause is a broken voltage sensing wire. I have seen this before.

    Brad
     
    #4 strawbrad, Nov 30, 2016
    mydaughtersprius likes this.
  5. mydaughtersprius

    mydaughtersprius New Member

    Joined:
    Apr 12, 2018
    1
    0
    0
    Location:
    Reading, PA
    Vehicle:
    2007 Prius
    Model:
    Touring
    Brad - First, thanks for this post! I have spent weeks playing with my daughter's '07. Replaced cells, balanced, cleaned all connections, checked every plug, checked every nut, etc. This is the first mention I found after hours of searching as to what could be causing p0afa. I am seeing the exact same readings in Torque as pictured above for block 14.

    Second, which wire is the voltage sensing wire and can it be replaced by itself or as part of a larger collection?
     
    #5 mydaughtersprius, Apr 12, 2018
  6. strawbrad

    strawbrad http://minnesotahybridbatteries.com

    Joined:
    Aug 9, 2011
    953
    1,002
    0
    Location:
    Minnesota
    Vehicle:
    2005 Prius
    Model:
    II
    The P0AFA code is closely related to the P3030 (voltage line snapped) code. The voltage sensing lines are the small wires on the front side bus bars. They all lead to the orange plug at the battery computer. The oscillation from negative to positive lasts just a short time and then one block will read zero and the next will read double.

    Look at the two wires closest to the battery ECU. I think it's the first one that's broken. The silver tabs can get very fragile. Look closely for hairline breaks. They can be solder or spliced or replaced.
     
    #6 strawbrad, Apr 14, 2018
  7. Hybrid Battery Exchange

    Hybrid Battery Exchange Member

    Joined:
    Nov 15, 2017
    67
    86
    0
    Location:
    Portland, OR
    Vehicle:
    2010 Prius
    Model:
    III
    I see this problem all the time in Oregon, it is caused by corrosion on the sensing harness plug and battery ECU. This needs to be addressed immediately, I've even had a battery catch fire while sitting on my bench a couple of years ago. See this thread for more information:
    The battery fires at ECU sense connector thread | PriusChat
     
    #7 Hybrid Battery Exchange, Apr 21, 2018
(You must log in or sign up to post here.)