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Steering angle issue c1231 - How to clear hard fault

Discussion in 'Prius c Technical Discussion' started by Prius city, Jul 10, 2022.

  1. Prius city

    Prius city Junior Member

    Feb 27, 2021
    2016 Prius c
    Any recommendations from the Prius Chat community on a steering angle issue mentioned below will be greatly appreciated. I have a steering angle issue on a 2016 Prius C 1B907EEF-2EE8-4482-921F-8705B9AD2CAB.png after taking the steering wheel off and then reinstalling.

    The steering angle module ( part number 89245-12050) is reading 1444.0 deg on techstream and does not change when the steering wheel is changed. The traction control light is also on and getting a code c1231 on techstream. Does anyone know how to clear the hard code c1231 with techstream or another program (cg 100 air bag reset system was mentioned on a you tube video but not a lot of detail was provided) and getting the steering angle module to start showing proper steering angle again on techstream. Any recommendations from the Prius Chat community will be greatly appreciated.
  2. ChapmanF

    ChapmanF Senior Member

    Mar 30, 2008
    Indiana, USA
    2010 Prius
    I don't have a copy of the Gen 4 repair manual to easily refer to. I'd have to find it here

    Toyota Service Information and Where To Find It | PriusChat

    where you would find it also. The section on the C1231 code would be where you would learn both exactly what the code is telling you (not some abridged memory jog you might find for it elsewhere) and what to do about it.

    If I remember right, steering angle sensors in earlier generations (2 and 3) were kind of self-zeroing. The ECU didn't care much what absolute signal the sensor was sending, but as soon as you drove for a bit, it would look for a moment when the yaw sensor read zero and the left/right wheel speeds were equal, and whatever the steering angle sensor said at that moment would be saved as steering angle "zero". So that approach required an accurate zero setting for the yaw sensor (and there's a Techstream procedure for that), but it avoided needing any separate special procedure for the steering angle sensor.

    I remember being puzzled in a Gen 2 because the steering angle shown in the Data List could be some goofy value, every time the car powered up, until it had been driven some and that auto-zero had taken place.

    I don't know whether Gen 4 details are at all the same.