1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Traction control activating at 10mph, no warning lights

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Towertro11, Aug 11, 2020.

  1. Towertro11

    Towertro11 New Member

    Joined:
    Aug 11, 2020
    5
    0
    0
    Location:
    01612
    Vehicle:
    2010 Prius
    Model:
    III
    Hi all,

    New to the forum, but have had Prius for about 8 years now.

    Current issue is with our 2010 model 3 with ~180,000 miles.

    Background:
    Car has seen limited use this year as it is our 'extra' car. I tried to drive it at least once a week, but it sat for around a month after the inspection lapsed.

    Problem:
    1: horn stopped working, unless I turned the wheel. Diagnosed bad clock spring. Replaced with a salvage part, but after installation, saw traction control and airbag lights.
    2: Ordered a new part (from China, risky, I know) for ~$80 on Ebay. Installed fine and no dash warning lights. I thought it was solved.
    3: Went for test drive and as soon as I hit 10 mph on the road, my foot is not on the brake, and the drivers front brake applies hard, abs clicking, traction control light flashing and alarm sound beeping. Occasionally the rear brake applies as well, mostly when turning back into the driveway. Car also throttles down to limit speed.
    4: Once back to the driveway, I entered maintenance mode, and the car drives fine.
    5: Tried to reset sensors by bridging 4 and 13 pins on OBD2 port. On test drive, brakes apply again.

    Again, at this point, I have no illuminated dash lights except traction control flashing when the brakes hit.

    Is there a way to tell what sensor is tripping? I know the dash lights flash codes when I bridged the pins, but not sure what codes I need. I recorded 3-1-6-3 for traction control. Did not make out others in the brief time I watched.

    Is there something else I am missing?

    Thanks in advance!
    John E
     
  2. Towertro11

    Towertro11 New Member

    Joined:
    Aug 11, 2020
    5
    0
    0
    Location:
    01612
    Vehicle:
    2010 Prius
    Model:
    III
  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    23,064
    14,969
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    31 (C1231) and 63 (U0126) both refer to inability to communicate with the steering angle sensor. That's attached to the "clock spring" so it's inevitably disturbed when somebody replaces that, so those connections are the first to recheck. In some cases people forget there even is a steering angle sensor, and find it out in the trash with the old clock spring.
     
  4. Towertro11

    Towertro11 New Member

    Joined:
    Aug 11, 2020
    5
    0
    0
    Location:
    01612
    Vehicle:
    2010 Prius
    Model:
    III
    Thanks for that lead!

    I knew the steering angle sensor was part of the clock spring assembly, but with the car sitting, I was unsure if it was that or a wheel speed sensor.

    I know the steering angle sensor was included in the part I got, but maybe that portion is defective? I think I have the old clock spring which only had a bad horn wire. Maybe I can find a way to put 2 together...

    John E
     
  5. Towertro11

    Towertro11 New Member

    Joined:
    Aug 11, 2020
    5
    0
    0
    Location:
    01612
    Vehicle:
    2010 Prius
    Model:
    III
    Well, made some progress.

    Pulled the clock spring and swapped out the steering angle sensor, and reinstalled.

    Car is now driveable without activation of traction control at 10 mph. No warning lights upon initial start up.

    However, after a short drive (~200 yards) now I have a traction control light on persistently. I noticed it after a K turn. I wonder if spinning the wheel loosened a connection?

    Bridged the 4 and 13 pins and am getting a 3-1 code from the traction control light.

    John E
     
  6. joshmuluba

    joshmuluba New Member

    Joined:
    Oct 9, 2023
    5
    0
    0
    Location:
    New York
    Vehicle:
    2012 Prius
    Model:
    Four
    Did you resolve your issue as I am having the same issue? The car would hard stop without pressing the brake. It is scary driving it now. I took it to dealer they recommended to do the alignment since it was a bit off center. As soon as I left dealership after alignment was done, the same issue re-occurred, the car squeaking hard stop and both front wheels locked up. I took it back to dealer and diagnosed with one code u0073 however they recommend to have ABS actuator / pump reported for $2500 which I declined since I lost faith with them. I used ebay techstream and got details on U0073 and noticed Wheel angle sensor is a lot off angle by 320 degrees. I also remembered a split sec right before the issue occurs the steering would feel weird since it is not center. I am definitely certain my issue related to steering wheel sensor angle is not aligned correctly. The techsteam shows the angle sensor is working and reporting the steering degrees. Please advise if I should replace sensor / clock spring - I attached the U0073 code detail
     

    Attached Files: