College Student vs "Check Hybrid System" and a dashboard lit up like a Christmas Tree..

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Mac Spencer, Sep 2, 2022.

  1. Mac Spencer

    Mac Spencer New Member

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    Hello all,

    My Prius broke down today, and as someone who has only done repair on non hybrid vehicles, I am in completely over my head. So, I'll tell you what happened and hopefully you can tell me what to do. This is something that I need to try to avoid taking to the shops as I am paying for college and have a very small budget for repairs like this.

    I was at a red light, had the 2010 Prius Three in Power Mode and went to accelerate at the green light and whilst accelerating it jumped forward a little and then it started to coast. I managed to get it into a parking lot, turned it off and back on, and then had the display screen "Check Hybrid System" as well as no power steering and every warning light on the dash lighting up. It pulled no codes on my diagnostic tool, even though it has a check engine light on - but I did manage to get it home by resetting the hybrid system (at least I think that's what I did, I removed a white cable from the fuse box for 10 minutes and plugged it back in) but now it is home and I have no clue where to start with diagnosing this thing.

    This weekend I plan to check the HV cooling fan and make sure it is working, but other than that I don't have a clue what to do.. any suggestions or advice would be greatly appreciated!
     
  2. bisco

    bisco cookie crumbler

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    welcome! sorry to hear about your troubles.

    how many miles on her?

    start the car and after the engine shuts down, open the cap to the inverter fluid reservoir. there should be ripples in the water, as the pump is always pumping while in 'ready'.

    if you're lucky,there's no movement, and you need a new pump.

    i would advise eco mode in the future and gentle accelleration with speed limit driving, of you can't afford repairs.
     
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  3. ASRDogman

    ASRDogman Senior Member

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    You might want to check the voltage of the 12v battery at the fuze box, or at the
    battery itself in the trunk on the passenger side. If it's low, you will get all kinds of
    weird messages. It's the easiest thing to check, and doesn't cost anything.

     
  4. ChapmanF

    ChapmanF Senior Member

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    Even on a college budget, I'd advise looking for a way to get yourself a diagnostic tool that will show you the codes. There are a bunch of possibilities for what problem you are having, and trying to solve it without knowing what it is can very quickly turn into a false economy that you can't afford, unless you happen to get lucky on the first or second guess.

    There's a thread in the Gen 2 forum comparing diagnostic tools and showing several options that should read all the codes from a Prius. It is in the Gen 2 forum because mr_guy_mann has tested the tools specifically with Gen 2 cars, but it's likely the better options on the list for Gen 2 will work with Gen 3 also.

    In the meantime, if you don't have a usable tool available, even paying the dealer for the usual hour of shop time to retrieve and tell you your trouble codes would not be a bad investment just this once.

    It is possible the codes will show that your issue is covered under a customer service program, which would probably make you happy. And if it is a covered problem, I think you'll avoid the charge for reading the codes, too.
     
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  5. Raygon

    Raygon Junior Member

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    got to try this on my car! the P0A08 check hybrid system code keeps popping up on mine as well.
     
  6. Grit

    Grit Senior Member

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    Take out a $10,000 school loan to fix it as Long as you don’t make over $125,000 as student. The current administration will cover all of it, I mean tax payers.
     
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  7. ChapmanF

    ChapmanF Senior Member

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    "As well" is not really the right thing to say here, as the original poster has not mentioned any P0A08, and in fact does not know which of the couple hundred possible issues might be involved yet.
     
  8. bisco

    bisco cookie crumbler

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    see post #2

    p0a08-dealer-clueless.151186
     
  9. Mac Spencer

    Mac Spencer New Member

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  10. Mac Spencer

    Mac Spencer New Member

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    Wouldn't any OBDII diagnostic tool pull the codes all the same? I have a friend with a different brand tool, so I'll try to get a hold of his and see if it shows anything. I know you can go to places like AutoZone and they will pull codes for free, so if I haven't made progress before then, I'll bring it to a parts house and get a code printout.
     
  11. ChapmanF

    ChapmanF Senior Member

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    No, they don't. A Gen 3 Prius has around two dozen ECUs in it, way more than most generic scan tools would even think of asking for codes, and they're not all together on a single CAN bus. We know that Toyota Techstream will pull all the codes, and as for any of the alternatives out there, we need threads like mr_guy_mann's linked above to help us learn which tools will and which won't.
     
  12. bisco

    bisco cookie crumbler

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    if the engine won't shut down, go for a ride and watch the battery meter. you can put a kleenex over the fan grille to check if it's running, they're usually very quiet, and clean is not abnormal.

    you can also check the inverter fluid by pressing the power button without your foot on the brake
     
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  13. Mac Spencer

    Mac Spencer New Member

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    UPDATE...

    I finally got around to getting the codes read. Here's what it pulled:

    P0A94
    P0A80
    C0200
    C0205
    C1259
    C1310


    From what I've gathered, I need new wheel speed sensors(C0200 and C0205), a new inverter pump(P0A94), and a hybrid battery pack(P0A80). I did check the inverter reservoir and didn't see any turbulence, so thats why I'm thinking the P0A94 was triggered by the pump. As far as I know the C1259 and C1310 codes are being triggered by the faults in the HV system, so they aren't really telling me anything.

    Correct me if I'm wrong, but the wheel speed sensors don't affect normal braking, but only the ABS. Are these sensors something that could wait? I've driven cars without ABS before, but I just want to check and make sure that ABS is the only thing they affect.

    The P0A80 "Replace HV Battery" confuses me. The battery pack was among the first things I tested, and each cell tested exactly 7.5 volts on my multimeter. I did notice a small amount of corrosion on the bus bars, would that trigger this code too? What would be the process for narrowing this one down?

    In the meantime, I'm getting a better OBD scanner with an app that will give me more information.

    I appreciate everyone's help.

    -Mac
     
  14. bisco

    bisco cookie crumbler

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    you definitely want to clean up any corrosion, and test the battery under load
     
  15. ChapmanF

    ChapmanF Senior Member

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    The P0A80 judgment that the ECU makes is not based on the static voltages you read with your multimeter, but on how the module voltages hold up under load.

    Any small amount of corrosion you might see on bus bars is unlikely to be a factor: if the nuts were properly torqued, if you remove them you will probably see clean metal underneath, where it really matters.

    P0A94 isn't about the inverter cooling pump (that would be P0A93). P0A94 is an issue with the DC/DC converter, which produces the 12 volts for operating the car when in READY. You may want to check at a dealer for coverage of that under a warranty extension.
     
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  16. rjparker

    rjparker Tu Humilde Sirviente

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    Agree that the Op needs to go to the dealer and request diagnostics, particularly as related to the inverter code since its likely to cause the stall and is still covered by Toyota. If it is the inverter, the diagnostics will be free. Various functions are in the "inverter" including IPM transistors and a dc to dc converter.

    Often extraneous codes appear when one device fails. While the hv battery is getting old (many have been replaced or repaired by now on a 2010), I doubt more than one thing failed during this incident. Same goes for the speed sensors.

    F1556B4E-0F84-4D70-B4BF-5599F92AF1A0.jpeg
     
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  17. johnHRP

    johnHRP Active Member

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    Yes, go to the dealership first for any recalls. At the same time, they usually will give you a proper diagnostic for that.
     
  18. Mac Spencer

    Mac Spencer New Member

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    Dropped the car off two days ago at the dealership, they're fixing two recalls that are probably unrelated and then the P0A94 code under warranty. After talking to the mechanic, the recalls are for a passenger side curtain airbag and a hybrid system update. As for the P0A94, he said they are ordering a transistor kit.. He said he was new to hybrids and wasn't able to explain to me what this does. Of course they are going to fix this when the part is not on backorder, but just out of curiosity, could anyone explain to me what a transistor kit does? I would assume it is to regulate voltage from the HV batteries, but that's just a weak guess at best.

    The mechanic said he also suspected the HV cooling fan to be bad, so I'll go ahead and replace that myself rather than pay Toyota to do it.
     
  19. rjparker

    rjparker Tu Humilde Sirviente

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    The transistor kit includes the power semiconductors in the inverter that makes everything work. Sometimes called the IPM.

    The proper terminology for the Inverter repair is a Customer Support Program which is a voluntary repair paid by Toyota only after a specified failure. A Recall is usually a safety oriented defect that is done regardless of its current operational state.
     
  20. ChapmanF

    ChapmanF Senior Member

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    This is what it looks like:

    [​IMG]

    As you can see, it is a fairly elaborate module. There is more to it than big transistors, but those are the main attraction: six each controlling the power flow to each of the big motor-generators (MG1 and MG2) inside the transaxle, and a couple more driving what's called the "boost converter", which takes the roughly 200 volt battery supply up to around 650 volts for the MGs, and the reverse when taking power from the MGs back to the battery.

    Besides the big transistors, this module has a bunch of supporting components monitoring the current and temperature of all the big boys, and reporting all that status back to the MG ECU that is calling the shots. Also, you see a pipe nipple sticking up at the top left and another at the bottom right. When you look at the inverter assembly under the hood, you can see those nipples sticking right out of it; they are where the coolant hoses attach. The liquid-cooled heatsink to keep those big transistors cool is also included in this module.

    IPM ("integrated power module" or "intelligent power module" depending on whom you ask) is an industry-standard name for this kind of thing. It's not really super-"intelligent"; its abilities are really limited to turning the big transistors on and off when the MG ECU says to, and protecting itself from gross overheating and overcurrent. The rest of the intelligence making the transaxle work is in the MG ECU and the power management control ECU.

    "Transistor kit" is kind of a funny name Toyota also uses for it, though often it makes people think more of a bag of transistors or something, not this assembled module.

    Each MG is a three-phase motor-generator, so each one has three wires connecting to it. In the IPM, each of those wires connects to two transistors, one connected to the + DC rail and one connected to the − rail, so the IPM can independently switch each of the leads of each motor to either + or − voltage, or none, at any given instant.

    The other two transistors are used in a kind of circuit that uses a big inductor and capacitor to either 'boost' the lower voltage from the battery to the higher MG voltage, or 'buck' the MG voltage down to battery voltage for charging.

    So that's the thing that got replaced any time your invoice says "IPM" or "transistor kit".
     
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