Prius ICE won't turn on. Limp mode.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Clytnjms, Feb 6, 2025.

  1. MAX2

    MAX2 Active Member

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    What scanner do you use to search for errors?
    If the EPS system is faulty, you should also have errors for this system.

    The system itself is powered by two supply lines. And you can check the voltage supply without a scanner.
    The 60A EPS fuse and the 10A ECU-IG NO.2 fuse should be intact and the contacts pin 1 (A) and pin 6 (B) should receive a voltage of 11-14 V relative to the case (pin 2) with the ignition on.
    See the diagram

    The output signal about the serviceability or malfunction of the EPS goes via the CAN bus pin 1 (В) and pin 7 (B) to the instrument panel.

    If the CAN bus is damaged, errors will be generated with the letter U.

    Your scanner does not record these errors?
     
  2. MAX2

    MAX2 Active Member

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  3. ChapmanF

    ChapmanF Senior Member

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    It's true that a lot of people struggle to make do with scan tools that won't show all Prius trouble codes because they don't talk to all the controllers in the car, and eventually (if the steering light stays on) the OP might want a better scan tool that can show those codes.

    But for the immediate future I think the OP's going to be busy with the P0A4B first, and then with the P3190 if that recurs.
     
  4. Clytnjms

    Clytnjms New Member

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    An inexpensive walmart one because that's all I could afford. Which one should i buy and how much is it?
     
  5. Clytnjms

    Clytnjms New Member

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    Which one should I buy? If it REALLY makes that big a difference and can help me get the car started I'll seriously look into it.

    Unfortunately I'm not Made of money and this ordeal has lost me 1k dollars easily and counting.
     
  6. ChapmanF

    ChapmanF Senior Member

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    I don't think you need it in order to pursue your top issues at the moment: the P0A4B, just go look at where the low-volt control wires plug in to the tranny, I'll guess they took some damage in the highway sign encounter. Fix that. Then the car can probably try to crank the engine. If P3190 persists, that's next.

    Once you've made some progress there and have some breathing room, you can review this thread:

    Gen2 OBD2 app review | PriusChat

    Yes, it's a gen 2 thread because that's what mr_guy_mann had available to test the different scan tools on. I don't think anyone has generously sent him a gen 3 to test on yet. But the tools that come out tops on that list are probably good bets for gen 3 also. The Autel is very much mentioned these days since he reviewed it in that thread.

    If a time comes when you've banished the engine and hybrid system problems, and the steering light is still on then and you want to know why, that's a place the better scan tool will help.
     
  7. Clytnjms

    Clytnjms New Member

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    Before it died while driving it'd last acceleration especially when driving uphill which I had to do everyday based on where I lived. The last couple days of driving it a few times it wouldn't make it uphill and was going at a literal snails pace so I had to pull over and wait 5 minutes or so to get up the hill then coast all the way down it while never having it to touch the gad pedal. Every day I go down that steep mountain it completely charges my battery according to the dashboard screen.

    The last couple days I had noticeable loss of power and acceleration and it'd make a sound like a paper plate touching an open box fan flapping noise with noticeable loss of power and acceleration. Literally the very next day a friend of mine and I were going to at the very least soak the Cat overnight or replace it with one I found on ebay and then it stopped while driving and hasn't started since. A few times after disconnecting the battery it'd move briefly before that red steering wheel exclamation point dashboard light showed up on screen. Now that dashboard symbol never leaves even after erasing codes.

    That accident was over 6 months ago. A friend of mine that knows 10x more about cars then I do looked everything over two separate times now but I'll go look again. I'm not exactly sure what I'm looking for but I'll go out there very shortly. I've driven it every day since that accident without that red steering wheel with exclamation point ever showing up. It has to be somehow related because it's the first thing that appears when I started driving after I reset it briefly and the only time I've ever seen it is now after my Car stopped driving. Hopefully your right somehow something got unplugged or disconnected but I seriously doubt it. I'll go check anyway. It's making strange noises when I try to turn off engine and the red battery dashboard light started appearing after I tried to get it working while broke down on side of road. Ive already hooked up a brand new battery to it to check. The red battery symbol went away after a couple minutes but it still didn't start. I even tried the other guys suggestion and unplugged the maf sensor. That didn't do anything either. I'm going to try here in a few minutes and see if any wires or damaged or unplugged
     
  8. ChapmanF

    ChapmanF Senior Member

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    Be guided by which codes you have. The most pressing is by far the P0A4B because you can't even crank the engine with MG1 out of the game, so focus is what you need for now.

    Flip to page 40 in this attachment and read the first few pages for a start. Now you know what this code is telling you about. Notice under WIRING DIAGRAM it says to refer to the earlier P0A1A-200 section ... which is outside of that small attachment I linked. If you look for the complete repair manual (bigger file....) it's in there.

    For convenience, here's that diagram:

    [​IMG]

    The code is about the generator resolver, so the connectors of interest are D7 and D29, which look like this:

    [​IMG]

    D7 is high up on the tranny:

    [​IMG]

    D29 plugs in at the inboard front of the inverter. It isn't orange, meaning it's officially low-voltage, but you still glove up, pull the orange service plug in back, and wait 10 minutes before working on it.

    I'm expecting (because P0A4B is an interphase short) that you may discover some wire damage bridging between GSN and GCS, though possibly they consider the excitation field a 'phase' too. Whatever, it's only six wires to check, and I won't be surprised if you spot the problem without a meter.

    If it doesn't turn out quite that obvious, next is to get the full repair manual and follow those troubleshooting steps, There are both voltage and resistance checks. That little excerpt above is filled with blue INFO buttons that would be hyperlinks in the real online manual, to sections like "CHECK GENERATOR RESOLVER" or "CHECK HARNESS AND CONNECTOR (INVERTER WITH CONVERTER ASSEMBLY - GENERATOR RESOLVER)" and the place you find those procedures will also be the P0A1A-200 section, in the full manual.

    Toyota Service Information and Where To Find It | PriusChat

    Often, when tracking down a problem with a car, our biggest wild swings are the ones where we tell ourselves what "has to be" true about a system we haven't completely understood yet. Happens to all of us. While still getting familiar with what the codes and the repair manual can tell you, a good approach is to stick pretty close to the given troubleshooting steps.

    As a sign on someone's office door might have said, never invent reasons not to check what the car has told you to check.
     

    Attached Files:

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  9. Clytnjms

    Clytnjms New Member

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    I really appreciate the help but my brain doesn't register literally any of this electrical kind of thing. I've literally never have learned anything in my life electrical related outside plugging guitars into amplifiers, cell phones and computers.

    My brain can't even register what your saying and the diagrams might as well be In Chinese because they mean and are doing absolutely nothing as far as helping me.

    In retrospect this wasn't a wise decision buying something this involved. I'm check mated. My brain might as well be toast because this is day 7 of all this constant new info overload. I don't have the desire or the will to keep trying to figure this stuff out anymore. All the wires look plugged in and fine to me.

    I'm check mated on this car. I'm pretty much done. I've wasted literally HOURS and HOURS and am literally not any closer to getting it started then where it was 9 days ago when it happened. I don't have the money to pay some over priced mechanic to fix it. I can barely get anyone that even wants to try and attempt to.

    I'm check mated and defeated for now. These diagrams do literally nothing for me as far as trying to figure any of this out. This is way over my head.
     
  10. Clytnjms

    Clytnjms New Member

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    Zero clue where I'm supposed to check. None of this means any sense whatsoever. No idea what I'm supposed to check and wouldn't know if it were damaged if it were.

    Everything looks plugged in to me. There is alot of dust and dirt surrounding the outside of Everything. I don't have any cleaner to clean anything with. I go to the store later I guess and buy something I guess but I'm starting to just want out of this. It has 240,000 miles. Both batteries are low. The engine guzzles oil. And now I have codes related to emissions abs gas lines possibly clogged up and damaged to.

    No thanks. I have A Honda civic as well with 200,000 miles that has literally never had not one problem. Even if it did it'd be 50x easier and cheaper to fix then this.

    Hopefully I can sell as is. I'm waving the white flag. To say I'm annoyed and frustrated would be the understatement of the century. All this wasted time for absolutely nothing. When all these issues are ambiguous and can have several solutions .

    Some people enjoy this sort of thing. I'm most definitely not one of them
     
  11. ChapmanF

    ChapmanF Senior Member

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    I take it you're not someone who has an ohmmeter handy and is comfortable using it?

    It's always tricky for us to guess where a new member is coming from experiencewise. Some join and post a lot of humble questions leading us to assume they don't know their way around a meter, but we can be wrong about that; others sometimes join and kind of blow the doors down leading us to make the other assumption, but we can be wrong about that too.

    Knowing your own comfort level is good. If you haven't got a basic multimeter or you're not sure you could use it to find an interphase short in a resolver circuit as diagrammed above, this may not be a DIY project for you. Or, because that circuit involves the inverter and high-voltage precautions are involved, if there is anything about that you feel less than comfortable about, that's an excellent reason to decide it's not a DIY project for you.

    That doesn't mean you might not have a buddy with those skills, or be able to find a reasonably-priced local tech, point them at the information in this thread already, and have them follow the indicated troubleshooting steps and find the solution.

    As to selling, if this were the only problem, I wouldn't be surprised at all if you could find a buyer who would be willing to troubleshoot and fix it and enjoy the car. What might get in the way of that, if anything, would be the list of other accumulated issues.
     
  12. MAX2

    MAX2 Active Member

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    The Prius is packed with electronics, it has more than a dozen different electronic control units, and therefore, when the hybrid fails, DIY repairs are sometimes quite complicated.
    Proper testing is the key to the right course of action during repairs.

    For people who have never done these repairs, it is like climbing Everest, difficult and dangerous.
    Turning to repair specialists is the only way out, but it requires significant costs.
     
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  13. Clytnjms

    Clytnjms New Member

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    Yes I'm slowly but surely realizing this.
     
  14. Clytnjms

    Clytnjms New Member

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    That's A good point aactually. At least I could give the person everything You all sent Me. I hate to sound ungrateful when You all are giving Me your time and expertise for free.

    I just tool a long break and a long sleep as well and feel more refreshed. Either that or I'm A glutton for punishment but I guess I'll l keep trying to figure it out. If I could at least get it started and running it'd make a night and day difference if I were to sell it.

    I'll look at those diagrams with a fresh set of eyes here shortly. Beyond frustrated yesterday. Just needed to get away from it for awhile.
     
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  15. Clytnjms

    Clytnjms New Member

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    It was A failed fuel pump. Which I was strongly leaning toward. The cataclean and seafoam I've ran through Gas tank must have cloggedit.

    That P0A4B was caused by me spilling coolant when I added some hoping that was the reason for the no start.

    P3190 is known for failed pump allegedly and I had that in conjuction with the P0456 and the EPS red warning light with exclamation point which I read on these forums that inadvertently can mean fuel related issues.

    There was also someone one reddit that ICE engine wouldn't start and had the EPS red warning light and exclamation point and the check hybrid system and it was the fuel pump.

    It was almost immediately after I added that can of cataclean to the gas tank that the situation happened so was almost certain it had to be related to that.
     
  16. rjparker

    rjparker Tu Humilde Sirviente

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    So are you saying you have it running now?
     
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  17. MAX2

    MAX2 Active Member

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    If the pump filter is clogged with all sorts of nasty stuff, then you need to at least clean the fuel tank by draining all the fuel from it.
     
  18. MAX2

    MAX2 Active Member

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    :eek:
    This is the first time I've heard that you need to add coolant to start the engine.
     
  19. Clytnjms

    Clytnjms New Member

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    It wasn't low. It was right above low. I figured it wouldn't hurt to at least try to add and see if its start and did spill a little. No idea itd set off a error code. Next time immediately clean up afterward. I didn't spill that much either and had a funnel.

    Ok I have a friend of mine that said he'd help me drain the gas tank tomorrow if you think that's what I should do
     
  20. rjparker

    rjparker Tu Humilde Sirviente

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    Is it running now?