Frankenstein GEN 1 2002 prius code P3191 P0141 P0125 and power steering shake

Discussion in 'Generation 1 Prius Discussion' started by blake9809, Mar 21, 2023.

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  1. blake9809

    blake9809 Junior Member

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    Story of the CAR: This is my first time ever owning a prius or hybrid vehicle. Since gasoline is on the rise and my commute to work is longer than most i thought it would be a good idea to get a fuel efficient vehicle and save some green. I found a old broken prius on craigslist. Previous owner said someone stole the catalytic converter and right away had a straight pipe welded in the area of where the cat use to be. Then drove it and the vehicle over heated and shut off. Found out that when the person stole the catalytic converter they jacked the vehicle up by the radiator and put a hole in the radiator. He brought it to a toyota dealer and they said the gasoline engine was detonated and needs a new engine. So i picked the vehicle up for $500 thinking i will just replace the gasoline engine for a couple hundred dollars and a weekend of wrenching in the garage. My thought was since he was driving it before seizing the engine everything else was in good working condition. So i purchased a used junk yard engine $200 and replaced the gasoline engine one weekend in the garage by myself. Should of had someone help me because pulling the engine off the trans and putting it back on by yourself is no fun task. I was able to disconnect the gasoline engine and pull just the gas engine out of the top of the vehicle :) many online say it needs to come out the bottom. After getting the gasoline engine in, new radiator, hooking up all the sensors, and filling with fluids i was eager to see if it started. NOPE did not start, tested the hybrid traction battery and was testing at 60v with dr prius app. I am guessing the vehicle sat off for around 6 months from when the engine blew to when i got a new engine in. So i searched locally for a hybrid battery for weeks and finally found someone selling a used old but good condition gen 1 battery for $600. Swapped the hybrid battery out and now the moment of truth, turned the key and it fired right up. No engine lights on and running good. I let it get up to normal temp around 190 degrees to burp and get the air bubble out of the coolant. Vehicle is idling good, shifting good, and blowing hot air. Now time to take it out for a test drive. I go to reverse and the steering wheel starts shaking like crazy, i panic not knowing whats happening. After searching online it appears the gen 1s are notorious for electric power steering problems. So i continue on down the road and after one block it shuts off and will not go faster than about 10mph. So i pull over scan the codes and see code P3191 P0141 P0125 so i clear the fault codes and vehicle starts up and runs just fine so i take it out on the highway and runs great for the next 30 miles, codes P3191 P0141 P0125 appeared again but did not affect driving ability. I let the vehicle sit for 8 hours and then decided to take it out again. I started the vehicle it started great and ran after one minute it died. So i started it again and it ran/drove good for the next 30 minutes. So i am looking for suggestions on how to fix the following issues listed below.

    Frankenstein replaced parts: (trying to keep this vehicle build under $1500 total)
    • Vehicle $500
    • Junk yard gasoline engine $200
    • Used hybrid traction battery $600
    • New engine coolant temp sensor ECT $20
    • Gasoline engine radiator $65
    • New spark plugs NGK $25
    • Fluids $65

    Problems car is having:
    1. Steering wheel shakes when backing up at low speeds
    2. Car dies shortly after you start the vehicle
    3. Fault codes P3191, P0141, P0125

    Questions i have:
    • Is it just annoying but safe to drive the vehicle with the power steering acting up? It appears to be a big pain to replace the power steering on these vehicles so if there is no safety concerns with the malfunctioning power steering i will probably just drive it as is. If i unplug the power steering will it still operate, just be hard to turn like it had no power steering?

    • Should i change the transmission fluid now? If so what fluid do you suggest putting back in ATF WS or ATF IV?

    • Why does the car die shortly after you start it? Is code P3191 indicating it could need the new ECU part# 8966147054? if i find a used ecu on ebay can i just swap it out or do i need to program the ecu to the vehicles vin#?

    • Code P0125 says insufficient coolant temperature for closed loop fuel control. Does this indicate i have a bad thermostat on the gasoline engine? or is this code coming up because the catalytic converter is missing and the second 02 sensor downstream is missing?

    • Code P0141 is 02 sensor heater circuit (bank 1 sensor 2) i would assume this code is coming up because the catalytic converter and the second 02 sensor is missing.

    I appreciate anyone that reads this entire thread and i truly appreciate any help, suggestions, or feedback on how i can solve the issues with Frankenstein
     
    #1 blake9809, Mar 21, 2023
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  2. Jakob

    Jakob Junior Member

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    Cheers for helping keep these running!
    This sounds like a common issue caused by torque sensors wearing out. Take a look at one of ChapmanF's writeups here. From what he says, I would guess this is not much of a safety concern simply because the assist torque is less at higher speeds, and the wobble at low speeds is likely just an annoyance. Curious that you only notice it in reverse though. Possibly just because you start your drives in reverse and the system gives up due to excessive noise before you shift into drive?
    ATF T-IV is the recommended fluid. I say sure, might as well change it unless you can tell it was changed recently. I think that stuff can last quite a while though. The official maintenance schedule says to check it every 30k miles or 2 years, for what that's worth.
     
    #2 Jakob, Mar 21, 2023
  3. ChapmanF

    ChapmanF Senior Member

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    It's usually safe-ish. You can sometimes keep the shaking down by having a more solid grip on the wheel. I don't mean that you have to muscle it into submission—it won't be like that; what I think happens is if your arms are just attached a little less loosely to the wheel, the mass of what's shaking goes up, dropping the resonant frequency below that of the torque sensor/ECU/assist motor system. You just magically notice it shakes less.

    I have read at least one thread here, maybe only the one, where somebody's failure mode, instead of a shake, was the assist motor full-powering the wheel over to one side. If I could name my first choice of failure mode, that wouldn't be it.

    So maybe if you're planning to leave it unfixed long-term, just unplug it. It'll be pretty comfortable at typical driving speeds; I even kind of liked that more-solid feeling better. At low speeds and in parking lots, it will be good for your upper body strength,
     
    #3 ChapmanF, Mar 21, 2023
  4. blake9809

    blake9809 Junior Member

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    ya usually start the drive reversing out of the driveway at home or out of the parking spot at work so you might be correct thats why i only notice it in reverse. Seems to be only when the steering wheel is far to the left.

    ok thanks i will poke around and see if there is a trans dip stick and check the condition of the fluid. If not i will probably change the trans fluid after a couple weeks if the vehicle continues to run good.
     
    #4 blake9809, Mar 22, 2023
  5. blake9809

    blake9809 Junior Member

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    Ya never experienced a shake like that in the steering wheel, i pooped the first time it happened. Had no clue what was going on but after digging online it made sense since the power steering is electrical and not like a standard power steering pump i would of seen before. Replacing the power steering looks like a huge job and i dont want to really spend any more money on this old antique so i will drive it a few more days or weeks and if it acts up more i will just unplug it.

    If i unplug it, is there two connectors i am looking for? should i just unplug them and leave the connectors or do i need to water proof the connectors? Will the ecu act up or go in limp mode if i unplug the power steering? Thanks for any help, i am learning a lot about these unique cars. I said from here on out the only car i will be purchasing is a prius because i know how to fix them now, :ROFLMAO:
     
    #5 blake9809, Mar 22, 2023
  6. ChapmanF

    ChapmanF Senior Member

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    The steering ECU is inside the cabin, behind the glove box, super easy to access. If you unplug it there, you spend zero time wriggling under the car and you don't have to worry about weatherproofing anything.

    You kind of have your choice of unplugging the torque sensor (that plug has skinny wires) as the ECU won't send any motor signals if it's getting no torque input, or just unplugging the motor (that plug has fat wires) so it can't send any motor signals. Or just unplug everything from the steering ECU and put it on your bookshelf. Yes, all of that by definition puts the steering completely in limp mode, but then that's the idea.

    It's possible the MFD might show what people keep calling the "PS MAIN EXCLAMATION POINT" screen (because it has three separate icons on it that can be gray or red, one for PS, one for the main battery, and a car with an exclamation point) and the PS icon will be red.

    I'm pretty sure in my 2001 I had the steering ECU unplugged a few times, one way or another, and didn't get that screen, but I don't know if an '02 will react exactly the same way. You might find that your choice of exactly what to unplug influences whether you have to look at that screen or not.
     
    #6 ChapmanF, Mar 22, 2023
  7. blake9809

    blake9809 Junior Member

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    [​IMG]

    ok so i am looking for something with the part number 89650-47190 on it that looks like the photo and its located behind the glove box. If i unplug all wires going to it then the power steering will be only manual and no electric assist. i will do this and see if the car throws any codes or what happens. Hopefully all is good and i can move on. thanks for the help
     
    #7 blake9809, Mar 22, 2023
  8. Jakob

    Jakob Junior Member

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    No dip stick unfortunately, but there's a fill hole on the lower front side of the transaxle where you can remove a bolt and stick something in to check the fluid.
     
    #8 Jakob, Mar 22, 2023
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  9. Bruce Berquist

    Bruce Berquist Junior Member

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    #9 Bruce Berquist, Mar 23, 2023
  10. Bruce Berquist

    Bruce Berquist Junior Member

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    With the p3191, there is an issue regarding the starting of the ICE (internal combustion engine).

    That doesn't necessarily mean the ICU start at first startup, I could mean that the engine is not starting up properly for the hybrid system while the car is running, putting a large load on demand and load on the HV Battery assembly, which will cause p0125 and p0141 and will definitely cause the car to go into limp mode with the turtle trouble light coming on.

    It is less like the ECU as it is more likely something with the ICE conditions. Probable culprit could be the throttle body and mass airflow sensor, could also be other things like spark plugs, coils, fuel injectors.
     
    #10 Bruce Berquist, Mar 23, 2023
  11. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    I am going to copy my post from the battery thread you were asking questions in. It will be to your benefit to keep your questions in one thread. Spreading the discussion will make it hard for everyone to follow.


    I have read through the problems you are having to keep the engine running. Why do you now suspect the battery that you just replaced? Are you getting battery codes? Do you know how to do a forced charge and discharge test on the battery?

    99% of original Gen 1 battery modules are now junk. I suspect the used battery you just bought was a factory replacement at some point. The battery modules have a date code. You can read this date code on a few of the modules by pulling the fan tube off the battery. The first two digits are the day, the third digit is the month with X,Y, and Z used for Oct, Nov, and Dec, the fourth digit is the year starting with A for 1999 and continuing from there. A serial number starting with 135L means the module was made May 13, 2010.

    Tracking down a P3191 engine failed to start code can be a bear. First to check is the MAF sensor. Be sure to clean the wires buried deep inside the top recess. A funky fuel pump can make the car seem possessed. The hybrid battery is NOT causing the engine no start problem.

    I am local to you and rebuild Prius batteries for a living. Feel free to call for help. My number is at the bottom of my post.

    Brad
     
    #11 strawbrad, Mar 27, 2023
  12. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    Hometown Hybrids have a couple of great videos explaining the engine no start.



     
    #12 strawbrad, Mar 27, 2023
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  13. blake9809

    blake9809 Junior Member

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    ok so after driving the vehicle a couple hundred miles in a few days here is an update on the vehicle. The vehicle has no problem starting or staying running no more P3191 code. I did nothing it just went away (y) and starting running great. Maybe Frankenstein just needed a couple days to wake up from the dead. I am still throwing Fault codes P0141 and P0125. P0141 because the second o2 and cat are missing. P0125 insufficient coolant temperature i think is because its been cold out 10-20 degrees and the vehicle does not warm up fast enough so the ecu throws a code? Vehicle runs around 190 degrees and has super hot heat. I am going to replace the thermostat soon to see if that helps it warm up quicker and if not then i will just leave that code alone and forget about it. The power steering only shakes when turning tight left at very low speeds. I am going to leave it for now but if it becomes an issue i will just unplug the power steering computer behind the glove box, this will disable the electric power steering but should still be manageable to drive.

    The last question i have is when its very cold out and i start the vehicle the coolant light comes on the dash and once its warm the coolant light goes off. Is this just telling me the vehicle is cold and once the light goes off its at operating temperature? :confused:

    I am very happy i got this vehicle running as it will help me with gas mileage to and from work. Thanks to everyone that chimed in and taught me some new things about these unique creatures. I am a prius fan now (y)
     
    #13 blake9809, Mar 28, 2023
  14. Jakob

    Jakob Junior Member

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    Yep, exactly. this is normal operation, at least for my vehicle.

    I'm skeptical the P0125 has to do with the speed of the engine warming up because the repair manual suggests the conditions that trigger it are tested only after the engine is "warmed up", although it doesn't mention a specific temperature.

    Looks like the primary thing it's detecting is that the upstream sensor doesn't report the exhaust is rich for a prolonged period, which corresponds to a high voltage from the sensor. This could be caused by a problem with the sensor itself or a short or open circuit (according to the manual), or it could be the fuel system, since I suppose this would also happen if the engine were just constantly running lean for some reason.

    The manual has some more diagnostic instructions, like reading the sensor voltage directly using a scan tool.
     
    #14 Jakob, Mar 28, 2023
  15. ChapmanF

    ChapmanF Senior Member

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    If the coolant light you mean is the blue one (top right), yes, that's exactly what that one means.

    [​IMG]
     
    #15 ChapmanF, Mar 28, 2023
  16. blake9809

    blake9809 Junior Member

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    perfect ya its the blue one i was seeing only come on when cold. So i assumed it was indicating the engine is cold and not to operating temp yet. The only reason i thought this is because other toyota vehicles i have owned before always had a cold light of some sort. So thats a relief to know its nothing serious
     
    #16 blake9809, Mar 28, 2023
  17. blake9809

    blake9809 Junior Member

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    what sensor do you suggest is making P0125 trigger?

    my understanding is Code P0125 says insufficient coolant temperature for closed loop fuel control. This would indicate the temperature of the coolant is not at the proper temp for closed loop?
     
    #17 blake9809, Mar 28, 2023
  18. ChapmanF

    ChapmanF Senior Member

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    There was a recent thread on here about P0125 in a later generation, and that thread talked about the detection conditions for the code in that generation.

    Because codes in the P0 range are all standardized, P0125 will always be some kind of "insufficient temperature for closed loop fuel control" code no matter what year or model of car, but I notice the way a Gen 1 detects it is a little different.

    From the 2001 repair manual, the detection condition is:


    After the engine is warmed up, oxygen sensor (bank 1 sensor 1) output does not indicate RICH (≧ 0.45 V) even once when conditions (a), (b), and (c) continue for at least 50 sec.
    (a) Engine speed: 800 rpm or more
    (b) Vehicle speed: 40 – 100 km/h (25 – 62 mph)
    (c) 20 sec. or more after starting engine
    ​
     
    #18 ChapmanF, Mar 28, 2023
  19. blake9809

    blake9809 Junior Member

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    So the code P0125 is indicating something in the fuel delivery is not correct? either o2 sensor number one is faulty or some sort of fuel delivery method is not working correctly like MAF, fuel injector, throttle body, etc. ?
     
    #19 blake9809, Mar 28, 2023
  20. ChapmanF

    ChapmanF Senior Member

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    The code is still an "insufficient temperature for closed loop fuel control" code. They are using the above detection condition to detect it.

    When the engine is cold, it is hard to get the mixture rich enough. The fuel just condenses on the cold metal instead of mixing into the air. Old engines had a "choke" you would pull to close off the air supply to make the mixture rich enough for starting. Over the next half minute or so, as the engine warmed and the mixture got richer, you would back off the choke.

    So your Gen 1 P0125 is saying "weird, been running 20 seconds, here I am driving down the road, and I still can't get the mixture rich enough. Am I warming up?"

    So while we can think of ways the detection condition could be fooled by other issues, like a faulty sensor or bad injector, that doesn't mean we should rule out the code indicating the exact thing it's meant to indicate.
     
    #20 ChapmanF, Mar 28, 2023
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