Steering Wheel controls

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by ThatOnePrius, Nov 5, 2025 at 4:11 PM.

  1. ThatOnePrius

    ThatOnePrius Junior Member

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    I'm trying to troubleshoot my steering wheel controls. I'm having issue with only 3 button not working. All others are working even cruise control.

    The Re circulation button, front and rear defrost button don't work. I can use the MFD touch screen to activate all three and they work no problem. I just cannot get them to work when pushing the button from the steering wheel.

    Things I have done-
    I've installed a new OEM clock spring. (The 3 buttons still don't work)
    I've installed another spare right side controls(The 3 button still don't work)

    The left controls work.
    The right controls, the Map/Info, Hands free, and both phone buttons work.

    I seen only a couple of threads with the same issue. The OPs replaced the clock springs but still had the same problem.

    I've looked at the wiring diagrams and it says when the Switch is pressed on the steering control it sends the signal to the A/C climate controller which then sends the signal to the relay. I'm assuming the relays are working because I can use the controls from the MFD to turn on the front and rear defrost and AC re circulation functions.
     

    Attached Files:

  2. mr_guy_mann

    mr_guy_mann Senior Member

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    If you have a wiring diagram then you should measure voltages at the left and right side steering wheel switch assemblies.

    There's three wires. A signal circuit for the left, one for the right, and a common ("ground"). Each switch has resistors. Pushing any one switch connects that side's signal to ground though a "unique" combination of resistors. So front defrost has one voltage, rear defrost has another voltage, etc.

    All three wires come from the AC ecu, go through the clockspring to the left switch. The common and right signal are extended from the left switch to the right switch.

    You have to do voltage testing to find if the problem is the right side signal wiring (in the dash to the ecu), or the left switch (or connections), or the extension wiring to the right side (or connections).

    Posted via the PriusChat mobile app.
     
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  3. ChapmanF

    ChapmanF Senior Member

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    Yeah, this should be straightforward with a step-by-step troubleshooting method and the wiring diagram. You can pull up one of the MFD diagnostic screens that will show you what all the control button inputs are doing, and see if those show what you do with each button, and if some don't, you can check along the wiring path getting closer to the ECU and MFD.
     
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  4. ThatOnePrius

    ThatOnePrius Junior Member

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    Thank you will try to tackle some of these steps tomorrow!


    I'll try the diagnostic mode first since it would be the easiest, then will go doing multi-meter checks like mr_guy_mann pointed out.

    Thank you both for the responses I'll see what comes up! Thanks!
     
  5. ThatOnePrius

    ThatOnePrius Junior Member

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    I have a quick question. Can I have the steering wheel air bag removed/ disconnected when I have these tests done?

    I've been unplugging the battery and removing the steering wheel air bag. I'm wondering if I can have it removed and then connect the battery to do the voltage tests without all the other airbags exploding?

    Update #1 Doing a continuity check the crossover harness from the left to the right controls checks out good.

    Update #2 Doing a continuity check on both clock springs 3rd pin at top row is not getting continuity to the bottom pin of the clock spring. This is a Yellow with Green dots wire from the left and right controls.

    I might have 2 faulty clock springs with the same problem will do further testing and keep yall updated.
     
    #5 ThatOnePrius, Nov 6, 2025 at 10:25 AM
    Last edited: Nov 6, 2025 at 12:11 PM
  6. ThatOnePrius

    ThatOnePrius Junior Member

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    Update

    The 69K mileage clock spring was bad. Here is what I found. 2 of the traces inside the clock spring ribbon cables had exposed copper traces showing. Out of the 2 only 1 trace(I assume Yellow wire) was broken. Did a continuity check and although one of the traces had exposed copper it passed, the other(Yellow wire) was broken. I assume the rolling wheels inside the clock spring wear out the insulation of the ribbon cable which eventually caused a break.

    The odds of having 2 different clock spring with the same problem just very very unlikely. That is why I found it very strange. I'm going to repair this ribbon cable until I can get a brand new replacement(OEM not from China).

    This has been a fun diagnosis and I have learned alot about the clock spring and how to test one in the future. I want to thank yall for the help and replys. I hope this helps someone going forward on how to test the clock spring.


    Conclusion-Bad clock spring.