2002 with P3125 sub code 325 with no start

Discussion in 'Generation 1 Prius Discussion' started by kutcht1, Mar 16, 2015.

  1. kutcht1

    kutcht1 Member

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    Pulling into parking lot and the triangle and exclamation light appear on dash. Drive about an additional hundred feet with what felt like lower power and no noises.
    - Check 12V after about an hour and it reads 12.4 volts.
    - Read codes and get P3125 sub code 325.
    - Temperatures and HV battery numbers all looked good.
    - Clear codes and immediately code comes back with no start, nothing. Did this many times.
    This code and sub code lead to the inverter failing. Being that there was no noise as a MG2 stator failure this also leads to an inverter failure right as the MG1 motor starts the engine? Inverter pump still running good as it was recently replaced along with ATX fluid. Within the last two weeks two HV modules have been replaced.
    Has anyone had experience with the P3125 and sub code 325 that can send me any insight?
    Thanks for all replies and guidance!
    TomK
     
  2. ChapmanF

    ChapmanF Senior Member

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    Page DI-294 in my manual covers inf code 325 saying for starters, make sure whether there are any other inf codes present. What did you read them with? There can be up to 5 such codes, I think; if you're using a ScanGauge, there are 5 separate XGAUGE definitions to enter to read them all.

    Manual says, any other codes present (besides 323, 324, 325), fix the other ones first, then see what happens. If P3125/325 is all there is, they go straight to inverter assembly replacement.

    The actual condition that inf code 325 refers to seems to be a short in the Finv signal for MG1. There's not much to do with that information as they don't publish any sub-assembly-level repair info for the inverter, but if you were EEish and wanted to give it a try, there you'd be.

    -Chap
     
  3. kutcht1

    kutcht1 Member

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    Thanks Chap! There were no other present when they were pulled. Mini VCI with techstream was used to get to the subcodes. I am not an electrical engineer but I do enjoy taking things apart when i does not matter if they get fixed afterwards. Those were what I found also in that it is leading the the code being set by the MG1 failing. I think I will go that route and get ahold of a used inverter and install it and hope it is not the MG2. I am hoping that someone chimes in with actual experience as this P3125 code seems to be a bit of a mystery even with the subcode with even the Toyota techs throwing parts at it.
    TomK
     
  4. ChapmanF

    ChapmanF Senior Member

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    Just to be clear, there isn't anything about this code to suggest failure of MG1 (or MG2). MG1 and MG2 are motors, parts of the transaxle. What's happening is that the inverter (big electronics box sitting on top of the transaxle) contains two power electronics sections that are designed to drive MG1 and MG2. The code indicates a problem in the power electronics (part of the inverter) driving MG1, not a problem in MG1 itself.

    Specifically, the subcode indicates a short in the Finv signal that runs from that power section back to the HV ECU.

    -Chap
     
  5. ericbecky

    ericbecky Hybrid Battery Hero

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    Yep. Swap out the inverter.
    Once installed, make sure you carefully purge the cooling system so that you do not have any air bubbles.
     
  6. kutcht1

    kutcht1 Member

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    I have found a used inverter unit and am ready to change it out. I can not find info on after I disarm the HV battery by pulling the orange plug and taking the 12V battery negative off, do I still need to worry about high voltage with the capacitors in the inverter itself?
    TomK
     
  7. ChapmanF

    ChapmanF Senior Member

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    Good thinking. Yes you do. They have a resistor network that slowly bleeds them off, after which you confirm zeroness with a voltmeter.

    Why can you not find the info? Are you going to do this without looking at the manuals on techinfo.toyota.com?

    -Chap
     
  8. kutcht1

    kutcht1 Member

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    Correct, it looks like a straight forward job of remove and replace. I can not see this being a difficult job at all, I just want to be careful as to not get voltage to myself. I already have the 12V unhooked and the orange plug pulled. Do the inverter capacitors bleed off by themselves over a few days?
    TomK
     
  9. ChapmanF

    ChapmanF Senior Member

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    Ok ... at least you know where to find the info if you change your mind and decide it might be useful. Do you have a place to look up the torques, etc.?

    A few days should be more than enough. Good luck.

    -Chap
     
  10. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    Hi Tom,
    I sent you a picture of the Inverter removal instructions. I would pull the back seat to access the HV leads of the battery. Check for voltage on these leads. The highest reading I have seen is about 20 volts and a voltmeter will quickly drain this voltage down. More often than not there is no voltage present. Just to be safe disconnect the battery leads.

    Brad
     
  11. kutcht1

    kutcht1 Member

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    I do not know where the picture of the instructions were sent. This is the only link with someone else doing this swap that I found. This link states 5 minutes for the capacitors for bleed off, so I would think over a day should be good. I will disconnect the two orange leads under the driver side rear seat to be sure.
    Replacing the Inverter Assembly on a 2002 1st Gen Prius « Russ' Do It Yourself Home Workshop
    I looked at it quite a bit last night and this is straight forward as far as I can tell with no moving parts (no need for torque values) and just a few orange power leads and some smaller wire cluster clips. Drain fluid and let the fun begin. I was thinking to just keep checking with a voltmeter along the way if something could be hot, but it shouldn't be.
    TomK
     
  12. ChapmanF

    ChapmanF Senior Member

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    Yes, please do. The caps on the motor circuits should also be discharged by now. But a meter read only takes a few seconds.

    High current electrical connections are worth torquing to the specified values, even if you don't consider them "moving". (There are specified torques for the breaker panel in your house, which moves even less than a car.)

    For the other, purely mechanical connections, the universal German torque gudentight may work if you don't have time to look up what's recommended ... but do remember the tapped holes are in aluminum (or have your ReCoil set handy).

    -Chap
     
  13. kutcht1

    kutcht1 Member

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    Thanks Chap! I was thinking that the German torque would be sufficient but thanks for the reminder of is being mostly aluminum, no grunting allowed. I think the person who did the electrical in my house was German. I really am hoping this is going to solve my P3125 sub-code 325. I was also thinking that even before I put new fluid in the inverter to try and start the car for a few seconds just to see, as there was nothing prior. Bad idea?
    TomK
     
  14. ChapmanF

    ChapmanF Senior Member

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    I think I'd be leery of testing it dry. The most time-consuming part of coolant replacement isn't the pouring it in, but the air bleeding. You might compromise by not going through the whole bleeding drill until you've quickly checked for signs of life. As long as you can go key-ON, not READY, and see the coolant steadily circulating in the reservoir, so even if it isn't totally bled you know it's not air-locked.

    -Chap
     
  15. kutcht1

    kutcht1 Member

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    SUCCESS!
    To conclude this issue if anyone else has this happen.
    It was indeed the inverter which failed, do not know which part of it. Replaced with a used unit and everything is working again as it should. The process took about 3 hours with 30 minutes of that bleeding the system. It was one of the most straight forward part swaps with really very little that needs to be done. The car sat for over a day with the HV orange plug disabled along with the 12V. I also disconnected the orange cables behind the drivers rear seat. I checked for current where there could be and not one of them showed voltage. I also replaced the front O2 sensor since everything was already off. Thanks to everyone who helped with this and a special thanks to Brad.
    TomK
     
    #15 kutcht1, Mar 21, 2015
    Last edited: Mar 21, 2015
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  16. strawbrad

    strawbrad http://minnesotahybridbatteries.com

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    Hope you can keep it running for more than a week this time!
    Brad
     
  17. kutcht1

    kutcht1 Member

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    Thanks Brad, you have been an great help and it would have been a huge challenge to keep this car on the road without your help. Atlas U-pull gave me a good deal on the inverter and seemed like a good business. It took about 2 hours to take out as I was checking things and about 30 minutes to replace and then 30 minutes to bleed the system. It went so fast I felt like I was missing something. I totally thought once everything was back together it would not have fixed the issue or get a dash full of lights but there was nothing. I almost could not believe it. The car gods were on my side this day as the O2 sensor also came out easily.
    Thanks again for all the help, I am sure I will need more as this car seems to like the attention.
    TomK
     
  18. 3prongpaul

    3prongpaul Hybrid Shop Owner, worked on 100's of Prius's

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    Actually make sure you first change the inverter coolant pump with a brand new one, unless you know it's been done recently. I wouldn't be surprised if your inverter failed because of a flakey pump. A healthy coolant pump will protect your inverter and transaxle. After installation bleed it well, drive a few miles to "shake things up" then bleed it again.
     
  19. kutcht1

    kutcht1 Member

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    Pump had already been replaced with a genuine Toyota pump a few months prior to this happening. Bleeding the system took about 30 minutes total, simple replacement of both the pump and the inverter. The system also got fresh super long life fluid. I have drove about 400 miles since and the fluid movement looks the same. Not sure why some people have trouble with the bleeding.
    TomK
     
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