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a Steering issue in gen 4th 2016

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Juhyun Park, Dec 18, 2016.

  1. Prodigyplace

    Prodigyplace Senior Member

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    That noise would drive me crazy too, especially with hearing aids that emphasize the high frequencies. :eek:
    I hear nothing like that on my Gen 4 purchased last October.
     
    #21 Prodigyplace, Jan 7, 2017
    Last edited: Jan 7, 2017
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  2. Ken_Prius4

    Ken_Prius4 Junior Member

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    I watched the video that park uploaded today. The problem I experienced is kinda different, the sound is more like plastic rubbers each other and it happens when I turn left or right to some a extent. A dealer shop finally changed a ring-shaped stuff under the steering wheel, surprisingly the problem was not solved!!! WTH. Today I got my car checked at another dealer shop, the staff told me they suspect the problem is from the power steering, this time they are going to change that power steering within two weeks after they get the part shipped out from Toyota. finger crossed.
     
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  3. goldfinger

    goldfinger Active Member

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    Your "crying rat" sounds like a PID loop that's gone into oscillation. I wonder if Toyota turned up the steering assist for the Korean market. Too high a gain leads to oscillation. Besides the annoyance this could burnout the power steering motor.

    You could test this theory by pulling the fuse to the power steering. If the sound remains it's something mechanical. If the sound goes away it's related to the power steering. Obviously the car would be difficult to steer so use great caution if you try this.
     
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  4. raspy

    raspy Senior Member

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    That's the exact same noise as my UK car!

    Posted via the PriusChat mobile app.
     
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  5. Juhyun Park

    Juhyun Park New Member

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    Hi goldfinger
    May I ask you what is the PID loop? I searched 'PID loop' with google, it was displayed almost about electronic circuit. Is this one kind of electronic circuit?
    And I want to know the basis of your opinion. From experience? Or is your job related here?

    Because I was greatly impressed by your professional explanations and I want to inform the Korean owners about this fact.

    Thank you!!
     
  6. Prodigyplace

    Prodigyplace Senior Member

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    Am I understanding you correctly?
    Replacing some steering column parts resolved the issue for one person. The old part could have been defective or the new part could have had a design improvement.

    Since this is only one particular case, it is not clear that this will resolve the issue for other owners with the problem.
     
    #26 Prodigyplace, Jan 9, 2017
    Last edited: Jan 9, 2017
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  7. Juhyun Park

    Juhyun Park New Member

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    Hi Prodigyplace.
    Thank you for your reply.

    Unfortunately, the new part was not designed improvement.
    It is only same designed parts and newest manufactured.

    This issue may be caused by incorrect assembly.
    But no one knows the cause. This is just speculation.

    I'm sorry that my English is not good. :D
     
  8. Prodigyplace

    Prodigyplace Senior Member

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    No problem. I just tried to make sure I understand.
    Thank you for your patience & taking the time to tell us about this problem.
     
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  9. goldfinger

    goldfinger Active Member

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    A PID (Proportional Integral Derivative) loop is a common control method using negative feedback to control a value. In this case the torque delivered to the steering rack based upon the torque input to the steering wheel. PID control loops can exhibit unstable behavior if not tuned correctly or if bad feedback is received.

    I suggest the sound you are hearing is oscillation in the steering assist motor due to control instability. If the feedback sensor in the column is producing too high a signal or if the signal is delayed in time (phase shifted) the system could break into oscillation. Parts at the outer edge of their tolerance combined with poor assembly could do it.

    Don't try to explain this to the dealer. Just tell him to throw parts at until it's fixed. Please report back and let us know.
     
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  10. I'mJp

    I'mJp Senior Member

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    Or if you are using lka, try turning it off.
     
  11. RCO

    RCO Senior Member

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    Lka = lane keeping assist
     
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  12. lohikaarme

    lohikaarme Troll

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    My Prius started doing this today! I hope it is a fluke and will check it again in a bit but as I was driving at around 45mph slight movements of the wheel caused this sound. Turning the wheel as if to pull into a parking space does not produce this sound.

    This prius was built in May of 2016 and is a 4 with the advanced tech and premium convenience packages
     
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  13. That_Prius_Car

    That_Prius_Car Austin Kinser

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    So far, my 2016 built in 7/16 and bought in 8/16 with 1 mile on the ODO, now has 3,100 miles and I haven't had this noise.
     
  14. Notquiterite

    Notquiterite Junior Member

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    I actually noticed my car doing this recently. However, it also happens even when the car is parked but still ON. It doesn't happen all the time, but has happened enough for me to notice. I haven't had the chance to bring it up to the dealer, but I should try to get a recording next time to show them as evidence. I am at 30k miles on a 2016 three touring.
     
  15. goldfinger

    goldfinger Active Member

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    I've been reading up on this. The 4th Gen uses Electric Power Steering (EPS) made by JTEKT. See a pic here https://www.marklines.com/ja/report/statics/a/rep1478_020_l.jpg. EPS's are getting more advanced in general, possible a little ahead of themselves. JTEKT’s EPS uses an assist control algorithm called J-ISM (can't make this stuff up). J-ISM detects vibration coming back from the wheels and tries to actively suppress it before it reaches the steering wheel. I guess we won't know when our tires are cupped or belts shifted anymore, after all ignorance is bliss. Anyway, J-ISM has more tricks. It uses variable phase compensation to stabilize self-excited vibrations or oscillations. Phase comp, however, is reduced at low torque to improve steering feel. See paper here http://eb-cat.ds-navi.co.jp/enu/jtekt/tech/ej/img/no1003e/1003e_07.pdf. This seems to be the region where people are getting the squealing sound.

    So, we drive a fancy high tech car with high tech problems and high tech annoyances. Turn up the radio!

    EPS without 17" wheels 8965047560
    EPS with 17" wheels 8965047570
     
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  16. RCO

    RCO Senior Member

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    ROFL!!!!
     
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  17. Juhyun Park

    Juhyun Park New Member

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    Hi all,

    Long time no see on this post.
    I read many posts and I got some update regarding this issue.
    Finally, Toyota in Japan responded regarding this issue.
    They recommended to exchange assembly part about 'Steering column'.

    This is official method.

    But, I haven't known that this parts as they recommended is improvement parts or not.

    Fortunately, among the owners who have experienced this issue, those who replaced the steering column are no longer experiencing these symptoms in korea.

    Please refer to other owners who have experienced similar symptoms and ask the dealer to repair it.

    Thank you.
     
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  18. pakitt

    pakitt Senior Member

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    Hi all - it seems the noise in the video is coming from plastic rubbing against plastic. It is really annoying!

    I have instead another noise coming from somewhere behind the steering wheel - I cannot understand if it is from the steering column or inside the dashboard plastic.

    The sound happens above 60km/h // 40 mph at specific RPMs of the ICE and sometimes depending on temperature. The noise is like a piece of flat plastic vibrating, resonating to some other vibration in the car.
    I tried touching anything reachable by hand on and around the steering wheel to see if I could stop it, but with no success. I also tried (and it is dangerous to do!) to adjust the steering wheel while driving to see if it made any change, but no success with that either.
    Never had this issue in Gen3.

    I was at the dealer for another reason (left front brake makes a repetitive noise when braking at low speed) and they told me to let them know next time I go for service if it is still there, because Toyota is asking them actively to report any noises. They also said to bring any videos I can make to see what it is. If they need to do something, they told me they will likely have to unmount the dashboard - which honestly I don't want them to do as that will introduce many more noises IMO!

    My car was bought in June 2016, so I suspect it was built between Feb and April of the same year.
    I should have waited a few more months to get it, but a service and change of tires on my Gen3 was coming up, and didn't want to invest money on it anymore.
    I will try to make a video of this noise and post it soon.
     
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  19. Prodigyplace

    Prodigyplace Senior Member

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    The month it was built is on a drivers door sticker.
     
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  20. pakitt

    pakitt Senior Member

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    I checked on the sticker, but there is no explicit indication of a manufacturing date. Is it encoded in a special way? e.g. last year digit and calendar week?