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about P0A38

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Annce, Nov 24, 2022.

  1. Annce

    Annce New Member

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    Dear friends, Happy Thanksgiving!

    The situation of my car is like this. I bought the 2010 Prius in 2021, when the odometer showed 140,000 miles, but I was on a long trip from Texas to California,The gearbox was completely broken and an old one was replaced. The hybrid battery is dead again. Just a few days ago, I bought a brand new battery and put on a new hybrid battery. The yellow triangle still exists. So I bought OBD check on Amazon, and the error code is P0A38, which I can't erase with the software. Has anyone ever encountered this kind of problem,And has anyone fixed them?
    I wonder if I need to replace the inverter? Or, check ECU? The ones under the passenger's feet, or check the MG2 module on the gearbox?
    Because this car I bought, the odometer has been modified, and I can't sell it, so I have to try my best to repair it.
    I don't know the actual mileage of this car now, but it shows that the mileage is 150,000.
    Thank you, everyone. If anyone has experienced this, I hope you can tell me. I am very grateful!

    Finally, I wish everyone a happy Thanksgiving again!
     

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    bisco likes this.
  2. Annce

    Annce New Member

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    I forgot to mention that, apart from displaying the yellow triangle, three driving modes can't be selected, cruising can't be used, driving and charging the hybrid battery can be used.
    Always display Check the Hybrid System…
     
  3. bisco

    bisco cookie crumbler

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    it sounds like a problem with the replacement tranny, or a wiring/connector issue.

    you might need tech stream for the sub codes
     
  4. Tombukt2

    Tombukt2 Senior Member

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    I think I had this code for a minute when we replaced the engine and the transmission in my 2013 I'll have to go back into the software and see if I saved the running information for right after the swap there was a bunch of codes and a bunch of nonsense to deal with it including the air conditioning and other things not operating properly The end-all be all to all of those codes after this engine swap was the hybrid battery was in horrible shape All the bus bar and nuts were frosted and looked horrible. The main thing that was done was a refurbished properly set up hybrid battery was put in the car and everything predominantly went away seriously. Other than the air conditioning all of the other codes went away
     
  5. ASRDogman

    ASRDogman Senior Member

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    Why did you just start replacing parts? A proper diagnoises might of saved you a lot of time and money.
     
  6. Annce

    Annce New Member

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    Thank you very much. The OBD I purchased and the software used with it can only detect this code. Other details cannot be displayed.

    Yes, I think there may be some other problems when changing the gearbox. There was no error code at first, but it appeared after driving for a period of time.
    Thank you very much for your enthusiasm and reply!

    Thank you for your reply, because I was driving a vehicle, and when I was in i10, I crushed a part of the scrapped truck tire. Maybe this incident caused my transmission oil pan to leak. Causing the gearbox to break down.
     
    #6 Annce, Nov 25, 2022
    Last edited by a moderator: Nov 25, 2022
  7. ASRDogman

    ASRDogman Senior Member

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    Okay, so you KNEW these parts were damaged? You could physically see the damage?
    I didn't notice that in any of your posts.... Unless I just missed it.... sorry..

     
  8. Mr. F

    Mr. F Active Member

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    The hybrid transaxle assembly has a sensor (thermistor) for keeping tabs on MG1 temperature. Its resistance is low when the temperature is high, and high when the temperature is low.

    upload_2022-11-25_13-47-32.png
    0 kΩ corresponds to a temperature of 401°F, and an open circuit corresponds to -58°F. These are both fault conditions because MG1 is never expected to reach these extremes of temperature.

    P0A38 indicates that power management control ECU has detected a resistance of 0 kΩ across the thermistor, which means that there is a short to ground either in the sensor, the connector or wiring harness, or in the ECU itself. You can figure out which part has the short by looking at the reading for "Motor Temp No2" in the power management control ECU data list (using Techstream) while disconnecting various parts of the circuit. The Repair Manual has a step-by-step guide for identifying the defective part.
    upload_2022-11-25_13-48-40.png
    Toyota does not sell a replacement for the sensor—if it is found to be faulty, the entire transaxle assembly (which includes the sensor) needs to be replaced.
     
    #8 Mr. F, Nov 25, 2022
    Last edited: Nov 25, 2022
  9. Tombukt2

    Tombukt2 Senior Member

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    Nice . Holey X. Well at least it's a quick one to sort out. J replacement . Low mileage .
     
  10. Tombukt2

    Tombukt2 Senior Member

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    I wonder if it could be fooled with external electronics like fooling the 02 sensors kind of?
     
  11. Annce

    Annce New Member

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    Thank you very much for your reply. All I know now is that ECU is at the foot of passenger. Other parts need to know more deeply. Thank you very much for your care and enthusiasm!
     
  12. Annce

    Annce New Member

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    You don't need to apologize. I first knew that the gearbox was destroyed, but after changing it, I thought there would be no other problems. Later, the hybrid battery was finished, and the oxygen sensor was finished. Now there is a problem with the temperature sensor. I swear, I will never buy such a used high-mileage hybrid car again.
     
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  13. Mr. F

    Mr. F Active Member

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    The hybrid transaxle assembly is the "gearbox" in a Prius.

    The sensor that is now faulty (belonging to the replacement transaxle) was probably near death at the time the replacement transaxle was installed in your vehicle. Also do not discount the possibility that it is a simple short in the harness or connector, which should be a lot less expensive to fix.
     
  14. Annce

    Annce New Member

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    Thank you very much. It seems that I'm going to recheck whether there is a circuit fault, not the whole transmission system.
     
  15. ChapmanF

    ChapmanF Senior Member

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    As Mr. F has emphasized, it's very much worth figuring out first whether it's the sensor at fault or the wiring or ECU. If it isn't the sensor, then tranny replacement would be (a) a very expensive way of (b) still having the same issue ... and fixing the issue would be faster and cheaper.
     
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  16. Tombukt2

    Tombukt2 Senior Member

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    I hate to think your second transmission has the same problem so it seems like it's a wiring issue ECU possibly something along those lines .