Help Troubleshooting (New) Red Triangle of Death - 2007 Prius

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PriusNoob86, Jan 29, 2025.

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  1. PriusNoob86

    PriusNoob86 Junior Member

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    Hi Prius Fam,

    My Prius is my secondary driver. I've only been driving it off and on in winter. Not much lately, so it's sat at the curb for a minute or two! I just got in yesterday to drive it, and was greeted with this array of warning lights on the dash. I hooked up the OBDII and checked Dr. Prius (I haven't used the app much but have heard that it can help troubleshoot issues). One cell bar looks very low. Could this be related? Anything else I can check to figure out what's going on? Engine kicks on and off just fine; I'm guessing the battery is the culprit?

    Thanks in advance for any feedback!
     

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    #1 PriusNoob86, Jan 29, 2025
  2. Brian1954

    Brian1954 Senior Member

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    You need a better scan tool than the Dr Prius app to read the trouble codes. Read this thread, https://priuschat.com/index.php?posts/3290690

    The Autel AP200 is a very good choice. It is $59 + tax on Amazon.

    Another option is to get and use Techstream software that the Toyota dealership uses.
     
    #2 Brian1954, Jan 31, 2025
  3. PriusNoob86

    PriusNoob86 Junior Member

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    Thanks, Brian! So would you say there's a fair chance that if I bought the AP200 tool, it could detect and convey why the red exclamation point and check engine light have appeared?
     
    #3 PriusNoob86, Jan 31, 2025
  4. MAX2

    MAX2 Active Member

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    The car has problems with the hybrid part. It could be the hv battery, mg generators, wiring, inverter. Your photo shows low voltage of the first pair of hv battery modules. It is necessary to check this pair, voltage and connecting wires. The problem could also be in the battery ECU or transmission ECU.
     
    #4 MAX2, Jan 31, 2025
  5. Brian1954

    Brian1954 Senior Member

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    Yes, the Autel AP200 will scan for all the trouble codes that your Prius has.
    Once you have the trouble codes, post them in this thread, and you will get additional help.
     
    #5 Brian1954, Jan 31, 2025
  6. PriusNoob86

    PriusNoob86 Junior Member

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    Thanks, Max! That was certainly my assumption - engine seems strong. I did go ahead and purchase an OBD scanner, so I'll see what it says and post results here.
     
    #6 PriusNoob86, Feb 2, 2025
  7. PriusNoob86

    PriusNoob86 Junior Member

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    I did purchase the AP200. I will get it scanned early this week and see what it says and upload the results. Thanks again.
     
    #7 PriusNoob86, Feb 2, 2025
  8. PriusNoob86

    PriusNoob86 Junior Member

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    Just getting back here with the results from the Autel diagnostic scan that I ran. Attached are the error codes I've received, as well as the Battery Report.

    The engine checked out with no error codes, as I suspected. It seems like it's been a workhorse. But of course the scanner picks up issues with the hybrid system. The codes that came up, for quick reference:

    -P0A80 Replace hybrid battery pack
    -P3000 Battery control system
    -B1421 Solar sensor circuit (passenger side) - A/C threw a code, though it seems to be running/cooling fine still
    -B1442 Air inlet damper control servomotor - A/C threw a code, though it seems to be running/cooling fine still

    Can anyone possibly tell from that battery report whether I could just change some of the cells and have luck getting the battery going again? I've never worked on the hybrid battery, but have kind of wanted a reason to. That is... I've wanted to work on it and replace some parts versus replacing it altogether, if it's an option.
     

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    #8 PriusNoob86, Feb 6, 2025
  9. mr_guy_mann

    mr_guy_mann Senior Member

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    The report shows that one of the two battery modules in block 01 has failed. There are MANY threads in the forums about HV battery repair (search DIY module replacement).

    In general it seems that "just" replacing some modules has a very small chance of working for more than a few weeks - if at all.

    The battery ecu monitors voltage levels of the 14 blocks. If they stay within around 0.3V of each other (over the entire State Of Charge operating range), there's no problem.

    The modules degrade (lose effective capacity) with time and use. As long as they degrade evenly, again no real problem.

    Any replacement module will very likely have different effective capacity & voltage levels. So at some point the block voltage difference will go above 0.3V for more than a few seconds, and more codes. Might happen trying to ready up, might happen when driving (high amperage in or out).

    Some here have used "grid chargers" to discharge-charge cycle the entire pack. Others use RC hobby chargers to cycle individual modules.

    Cycling the modules can improve effective capacity - hopefully bringing all modules up to the "same" level. (This is what some "refurbished" packs are).

    Do your research. Can take a fair bit of knowledge, time, and money to "do it right". Even then you might get 2-3 years. Do it wrong and it might never work at all.

    Refurbished packs can work, but understand everything about the warranty as you'll likely need it.

    Another option is to find a (good - complete) used pack from a junkyard.

    Last time I got a new pack from Toyota - zero problems.

    Posted via the PriusChat mobile app.
     
    #9 mr_guy_mann, Feb 7, 2025
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  10. PriusNoob86

    PriusNoob86 Junior Member

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    Mr_guy_mann, love the name. Thanks for the very detailed response. So the gist of this is that the module replacement/repair method is not very reliable and might end up being a lot of research and work on my end towards a possibly disappointing result.

    So the other unfortunate thing is I had just replaced the passenger side CV axle to stop some scraping and grinding before the battery went bad. My own DIY that I was fairly proud of, having not done much work with suspension components before. The goal was actually to get it fixed to sell it, more than likely. The car has been fantastic but went from being my primary driver to one that mostly sat by the curb and didn't get driven much.

    In light of that, I'm still interested in possibly buying a used or refurb'ed battery pack, knowing that I won't have it for the long haul, but would like to have it in working order when selling. Do you think it's worth the investment before selling it? Sell as-is? Obviously this is getting outside the scope of the diagnostic , but I'm just trying to decide how to proceed. Any input from anyone is appreciated. And I say a used pack because I assume the dealer would charge close to $2,000 or so for a new one?
     
    #10 PriusNoob86, Feb 8, 2025
  11. MAX2

    MAX2 Active Member

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    By errors P0A80:
    The first pair of modules has a lower voltage relative to the second pair of modules.With a high degree of probability, one of the modules in the first pair has failed.

    B1421 do not pay attention to this error in the light sensor for automatic lighting, you simply do not have it
    B1442 error associated with the incorrect position of the damper for supplying air from the air conditioner to the cabin. Mechanical wear of the tracks, the part of the damper with a good contact group is changed. But this is not scary, you can drive if you change a couple of modules in the high-voltage battery.
    And one more thing. Gen2 allows movement immediately after starting, but until the engine has warmed up, the electrical component is used more. Your engine and battery have not warmed up, but you pressed the gas and began to accelerate decently. A large current passing through the old battery makes it work at the limit of its capabilities.
     
    #11 MAX2, Feb 9, 2025
  12. ChapmanF

    ChapmanF Senior Member

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    There is a light sensor on the dash even in cars without auto headlights; it's used so the HVAC can proactively respond when you drive in and out of strong sun.

    The B1421 code is just provided to give you a way to tell if that sensor is working: if you have the code when no strong light is falling on the sensor, and strong light there makes the code go away, then the sensor is working.
     
    #12 ChapmanF, Feb 9, 2025
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  13. mr_guy_mann

    mr_guy_mann Senior Member

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    It was about $1800 - $2000 "at cost" about a year ago. That was for a Toyota pack sitting in a crate & doesn't account for the (refundable) core charge. You would have to install it or pay for labor.

    "List price" was something like $2500. I have heard that prices have gone up a bunch recently.

    Posted via the PriusChat mobile app.
     
    #13 mr_guy_mann, Feb 9, 2025
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