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Traction control activating randomly

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Eduardo Mendez, Oct 4, 2022.

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  1. Eduardo Mendez

    Eduardo Mendez New Member

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    I have a 2012 Prius two. I swapped the clock spring and steering angle sensor then the traction control started activating randomly, sometimes at 10-20mph (pretty scary). Made sure center of the steering sensor reads as 0 degrees in tech stream. Did the memory reset and test mode to calibrate again. I got all the lights to turn off and no codes. Drive for 30 min no issues, then I get to red light and when I try to accelerate I feel the car has no power then traction control kicks in again, the. Stops and when I press the accelerator kicks in again. If I disconnect the steering angle sensor, the tcs light comes on but I am able to drive the car without ABS/TCS activating randomly. Does that mean is a bad steering angle sensor? Any ideas?

    thanks in advanced.
     
    #1 Eduardo Mendez, Oct 4, 2022
  2. Tombukt2

    Tombukt2 Senior Member

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    Mine was doing this because of mismatch tire sizes sounds like maybe you do have a bad sense or if you can clear it in tech and then it comes back seems like it or something similar
     
    #2 Tombukt2, Oct 4, 2022
  3. ChapmanF

    ChapmanF Senior Member

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    New angle sensor, or old angle sensor moved to the new c;lockspring? Toyota parts or aftermarket?

    Any dash warning lights? If so, what trouble codes?

    In Techstream, the "ABS History" function can show you the most recent four times ABS or traction control activated, and what all of the sensors were saying at the time. That might be helpful information.
     
    #3 ChapmanF, Oct 4, 2022
  4. Eduardo Mendez

    Eduardo Mendez New Member

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    Tires are the same and have not been changed.
     
    #4 Eduardo Mendez, Oct 4, 2022
  5. Eduardo Mendez

    Eduardo Mendez New Member

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    new clock spring and angle sensor. Aftermarket parks. I had the “lost communication to steering angle sensor” code. I did the reset memory and then test mode on tech stream and it got rid of all codes. Then first trip (20-30 miles) was fine. On the way back it did it again I will check the abs history.
     
    #5 Eduardo Mendez, Oct 4, 2022
  6. Tombukt2

    Tombukt2 Senior Member

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    I gathered your tires were correct I was just saying that I made this happen kind of on purpose by putting the wrong size tires I think on the back of the car I have four tire sizes I keep in my garage for the vehicles I own and I grabbed a set of 60 series instead of the 65s for the Prius.
     
    #6 Tombukt2, Oct 5, 2022
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  7. Eduardo Mendez

    Eduardo Mendez New Member

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    So i got it to trigger again, here is the report, does the steering angle sensor seem off? 837 degrees? also i parked, shut the car off then back on and the sensor readout was back to normal. any ideas?
     

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    #7 Eduardo Mendez, Oct 8, 2022
  8. ChapmanF

    ChapmanF Senior Member

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    That does look odd, doesn't it? Every other reading (no yaw, no lateral g, all wheel speeds the same) is consistent with driving straight ahead, but steering angle says hard over to the left.

    Does that sensor mostly show as around 0 degrees in the live data list when the wheel's pointed straight ahead?

    I'm not sure what to make of SMC being off and SRC being on. My 2010 seems to switch both of those together. At least it does when I'm braking with the pedal. I guess I've never watched what it does with them when VSC activates.
     
    #8 ChapmanF, Oct 8, 2022
    Last edited: Oct 8, 2022
  9. Eduardo Mendez

    Eduardo Mendez New Member

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    Yes and no, right after ABS kicked in, i pulled over and checked live data (i had my laptop with me as i was waiting for it to happen) and i saw that the steering angle sensor had those odd values (800,700ish, 900ish) however I turned the car off then back on and it was back to normal (0 degrees)
     
    #9 Eduardo Mendez, Oct 9, 2022
  10. Eduardo Mendez

    Eduardo Mendez New Member

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    also all 3 lights (ABS, TCS and check engine) show up randombly with code u0073 (only code) and then they go away after restarting the car. Is this the steering angle sensor losing communication/not working properly?

    Thanks!
     
    #10 Eduardo Mendez, Oct 10, 2022
  11. Hokie-Dave

    Hokie-Dave Member

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    Is it setting off the C1231 code when the SAS is reading the 837.3 degrees when you turn the car on? I'm currently researching this issue myself, except the only difference is my TCS light is on all the time and my SAS reading doesn't change from the 837 (or there abouts). From what I've read so far it is a faulty SAS if you can confirm that the SAS is receiving power. I haven't dug in there yet to check on how to check for voltage to the sensor.
     
    #11 Hokie-Dave, Oct 10, 2022
  12. Eduardo Mendez

    Eduardo Mendez New Member

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    no whenever this happens only u0073 is present. Whenever i turned the car off and then back on SAS reading was back to normal.
     
    #12 Eduardo Mendez, Oct 10, 2022
  13. ChapmanF

    ChapmanF Senior Member

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    There are different ECUs in the car that can report U0073. The code means the CAN interface (in whatever ECU is reporting the code) seems to be off, or not connected to a working CAN bus.

    Some scan tools only show you codes, others show you the codes and which ECUs they came from. Obviously, the latter kind is more useful when looking at communication codes.

    The "CAN communication system" section in the repair manual has the most information on troubleshooting this sort of issue.
     
    #13 ChapmanF, Oct 11, 2022
  14. Eduardo Mendez

    Eduardo Mendez New Member

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    i think it might be a bad SAS. Whenever u0073 comes on i pulled the freeze frame and saw detailed code 462 which i think its related to loss of comms to SAS. Here is the report.
    Having the 462 detail code on the freeze frame does it tell it’s the loss of comms with the steering sensor?
     

    Attached Files:

    #14 Eduardo Mendez, Oct 11, 2022
  15. ChapmanF

    ChapmanF Senior Member

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    That report is good because it shows both which ECU was reporting the U0073 (it's the skid control ECU) and an INF code 462. And in the ABS/VSC/TRAC section of the repair manual, the detection condition for U0073-462 does say that it's either:

    1. Steering angle sensor communication is disabled for 1
    second or more.
    2. Steering angle sensor communication is disabled once
    or more per 5 seconds 10 times or more within 60
    seconds.
     
    #15 ChapmanF, Oct 11, 2022
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  16. Eduardo Mendez

    Eduardo Mendez New Member

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    So after a new clockspring and steering angle sensor combo, zero point reset and recalibration, no lights on the dash. Then the next day on a drive I got the u0073 with the same detailed code 462, which disapears after turning the car on/off but the DTC/freeze frame stays. Then the next day, Traction control kicked in again at 48 MPH, no DTC, no lights, no codes, nothing. Not sure what to do next, Currently driving the car with the steering angle sensor unplugged since it is the only way i have been able to not have the ABS/TRAC activate while driving.

    I am attaching the ABS history freeze frame from when it triggered at 48 MPH
     

    Attached Files:

    #16 Eduardo Mendez, Oct 18, 2022
  17. ChapmanF

    ChapmanF Senior Member

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    Where are these parts coming from?

    This time, the freeze frame looks like the wheel is a full turn to the right, but the car is going straight ahead according to the g forces and wheel speeds....
     
    #17 ChapmanF, Oct 19, 2022
  18. Eduardo Mendez

    Eduardo Mendez New Member

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    Ebay, not OEM, which i know is not the best but this is the 3rd clockspring and 3rd SAS. The car was going straight when it happened.
     
    #18 Eduardo Mendez, Oct 19, 2022
  19. ChapmanF

    ChapmanF Senior Member

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    It wouldn't surprise me that if the skid ECU sees the steering wheel apparently hard to the right but can tell from g forces and wheel speeds that the car is going straight, it will think you are skidding.
     
    #19 ChapmanF, Oct 19, 2022
  20. Eduardo Mendez

    Eduardo Mendez New Member

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    so do you think its bad SAS sensors?
     
    #20 Eduardo Mendez, Oct 19, 2022
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