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2008 Prius with C1241, C1310, C1378

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Hank Weiss, Mar 1, 2021.

  1. Hank Weiss

    Hank Weiss New Member

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    About 2 weeks ago the check engine light came on. There was no change in performance that I noticed. About a week later the Brake System warning light activated followed by the red triangle within a day or maybe the same day. Performance changed drastically. The combustion engine is doing most of the work it seems. The car severely lags when accelerating from a stop and it sputters here and there. The battery charging bars go down to one bar real quick when the car is working and then back to full real quick when the car isn't working much.

    Orielly's says the 12v battery is good. A friend suggested to start by replacing the Brake Control Power Supply Assy ECU if I can find a used one for cheap. Any other advice for me?
     
  2. bisco

    bisco cookie crumbler

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    sounds more like the hybrid battery
     
  3. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    From the description, it would appear that the HV battery is failing.

    How many miles of the vehicle, and is the HV battery still the original OEM?
    Did you noticed the HV battery fan in the rear passenger area running at an audible level?

    There may be additional OBD2 codes (DTCs) stored in the ECUs (computers), and a toyota hybrid compatible scanner can retrieve them. Many prefer using a 'Mini-VCI' cable and techstream (dealer technician software) or a windows device. Some get by with using an OBD2 bluetooth adapter with an App like Dr Prius or Hybrid Assistant. Which scanner was used for the above DTCs?

    Don't fall for the refurbished/rebuilt options, either a DIY repair, low mileage used, or install a NEW hv battery
     
  4. Hank Weiss

    Hank Weiss New Member

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    • The vehicle has 155k miles. I bought the car at about 80K miles. I haven't replaced the battery. I doubt it was replaced before I bought it either.
    • I used a scanner at Orielly's. I did it myself and it was my first time so I could've missed something. Checked it several times though after disconnecting battery and harness to other parts by the battery.
    • Yes I can hear the fan going hard quite often
     
  5. SFO

    SFO Senior Member

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    Likely an OEM then, and could be a good candidate for DIY rebuilding, are you mechanically inclined and process tools?
    You didn't miss anything, that was a basic limited scanner that wasn't hybrid compatible. Knowing the codes (DTCs) can be helpful.

    Best to read and record the OBD2 codes before disconnecting the 12v, which will erase them until they are set and stored again.
    Tell tale sign of a failed/failing HV battery.

    FYI: you're posts are moderated until you've posted five times.
     
  6. Hank Weiss

    Hank Weiss New Member

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    Scanned again today. Showed a C1259 in place of the C1241 this time. The other two codes were still there. I have tools and I’m pretty mechanical. I have friends who are very mechanical so I should be able to handle a DIY option.

    Do you have any incite/advice for how to approach that best? Looks like Amazon has the cell modules for about $30.
     
  7. SFO

    SFO Senior Member

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    Start by grabbing a "mini-vci" cable ($20), then you will have access to the same OBD2 scanning software as the dealership. If that is too much, then pick up an OBD2 bluetooth adapter, but first research here before making a purchase : Hybrid battery diagnostic and repair tool for Toyota and Lexus
    Best to go one step at a time. Do you plan on using the vehicle for anything?

    If not, and while you wait for the mini-vci cable to arrive (pick a local seller for faster delivery), now might be a good time to learn how to get at and remove the HV battery, and clean the HV battery fan.

    There are videos and threads on HV battery removal and fan cleaning, but following the Hybrid Automotive guide step by step will get you most of the way there : 2004 – 2009 Toyota Prius Plug-and-Play Car Harness Installation Instructions | Hybrid Automotive

    Once you've removed the HV battery main cover, look for leaks/stains around the modules and underneath on the bottom pan. Check the HV battery ECU and associated connectors on the drivers end of the pack for corrosion, also get a visual on the level of corrosion around the voltage sense wires, busbars and nuts. If it looks bad, you may want to order a new harness for $60.

    For others :

    Here is the workup for DTC C1259 and DTC C1310 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/repair%20manual/04pruisr/05/21avn/cic12595.pdf

    Here is the workup for DTC C1241 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/repair%20manual/04pruisr/05/21avn/cic12414.pdf

    Here is the workup for DTC C1378 : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/repair%20manual/04pruisr/05/21avn/cic13784.pdf
     
    #7 SFO, Mar 2, 2021
    Last edited: Mar 2, 2021
  8. Hank Weiss

    Hank Weiss New Member

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    Something to mention is that when I had nothing but check engine light a few weeks ago a scan reveled a P0456 (evaporative emission system leak). The car did begin to sputter a little like when a fuel pump is letting go. Reading through these different threads has me believing that one problem can ultimately lead to many other codes popping up in a Prius for systems that are effecting by the original problem but don't necessarily have an issue themselves. Any new feedback base on this info perhaps?? Thanks!
     
  9. SFO

    SFO Senior Member

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    Given your above description, the HV battery is failing (or has failed), scanning with a hybrid compatible OBD2 scanner/app is best.