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

Code P3030 present after changing bus bar and sensing wires

Discussion in 'Gen 2 Prius Technical Discussion' started by dshawster, Jul 1, 2021.

  1. dshawster

    dshawster New Member

    Joined:
    Jul 1, 2021
    2
    1
    0
    Location:
    Maple valley, wa
    Vehicle:
    2005 Prius
    Model:
    ----USA----
    Hello everyone!
    I have a 2005 Prius that gave a P3030 code the other day after sitting for a few weeks (red triangle, check engine light and an explanation point). I did some research on this forum and checked the sensing wires on the battery pack. They had some corrosion on them and I decided to order a new harness from Toyota, the $100 seemed worth it instead of trying to repair the small gauge wires. After installing the new harness today the code is still present, I removed the battery again and did a continuity test on the wires from the terminal to the connector that goes into the ECU for each wire and they checked out good at close to 0 ohms. I inspected the ECU and there is nothing obvious there, the PCB has a good coating on it and no corrosion or burnt electronics. I’m at a loss what to do or check next, I have a basic OBD scanner that can check and clear codes but cannot see the individual cell voltages while the battery is installed. I’m willing to shell out the money for one to help diagnose if there are recommendations on what to get.
    The car drives fine and the energy usage screen shows the battery charging up while driving and the battery putting power to the drivetrain. Thanks in advance for any help.

    Dave
     
    #1 dshawster, Jul 1, 2021
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    110,166
    50,060
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    most are using mini vci and old windows. not a lot of money, but sometimes tricky to set up
     
    #2 bisco, Jul 2, 2021
  3. mr_guy_mann

    mr_guy_mann Senior Member

    Joined:
    Sep 3, 2020
    3,676
    1,718
    0
    Location:
    NJ-USA
    Vehicle:
    2006 Prius
    Model:
    Four
    Getting a mini VCI cable (that comes with a bootleg copy of Techstream diagnostic software- amazon or ebay) is a good idea for anyone working on an older Toyota, esp a Prius. Another possibilty is to get a compatible OBD2 adapter and use an app like Dr Prius or (android) Hybrid Assistant - which let you see data from the battery ecu.
    Many here have both- vci and obd2.

    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Jul 3, 2021
    bisco likes this.
  4. JoeX

    JoeX Junior Member

    Joined:
    Aug 26, 2015
    10
    6
    0
    Location:
    PA
    Vehicle:
    2006 Prius
    Model:
    Two
    remove both harnesses and check individual battery voltage. I had this happen and the acid followed the sensing wires all the way to the controller where it shorted and burned off 4 or 5 pins inside connector on the controller
     
    #4 JoeX, Jul 7, 2021
  5. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    24,915
    16,216
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    Pins getting messed up in that connector is a fairly common problem, but I'm not convinced the reason is electrolyte following the wires there all the way from the battery modules.

    As a minor point, but worth remembering, the electrolyte in the NiMH battery is a strong alkali—about as far from an acid as you can get on the pH scale.
     
    #5 ChapmanF, Jul 8, 2021
  6. dshawster

    dshawster New Member

    Joined:
    Jul 1, 2021
    2
    1
    0
    Location:
    Maple valley, wa
    Vehicle:
    2005 Prius
    Model:
    ----USA----
    Thanks for the replies, I would have replied earlier but I didn’t realize I had not set up notifications for the thread.
    I did check the ECU pins and they all looked good with only minor corrosion on them, no electrolyte present from any batteries and each cell measured around 8.3 volts or so, I opened up the ECU and did a continuity test from the outside connection pins to the solder joint joints on the PCB and it all checked out good. With a little more research I found a service bulletin stating if the continuity of the sensing wires check out ok then replace the battery ECU.
    I ordered a unit off eBay for less than $100 shipped, it had a different part # but said it was for an 04-09 Prius. I installed that today and it cleared the problem! Thanks for the suggestions.
     
    #6 dshawster, Jul 9, 2021
    Mahal likes this.
(You must log in or sign up to post here.)