ABS Wheel sensor replaced and wheel bearing. Still issues.

Discussion in 'Gen 3 Prius Main Forum' started by dangerbag, Oct 16, 2021.

  1. dangerbag

    dangerbag New Member

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    2010 Prius starting throwing the three warning lights (yellow ABS, red BRAKE, & yellow slip issue). As the vehicle was hit at the front passenger side (extremely low speed impact), I started with the front left and right. I assumed the collision had thrown off the sensors or the wheel bearing hub. Since all of the collision damage was repaired by a body shop, I assumed this repair was overlooked. The collision happened a year before the vehicle threw codes. They could be totally unrelated.

    The three codes came on after I had to brake hard to avoid another driver that cut me off. I researched the codes here and decided the wheel bearing and speed sensors needed to be replaced. I bought new wheel bearings and hubs (mid priced $150/each) and left and right front speed sensors. As OEM sensors where priced at $300 each, I ordered Amazon cheap sensors for $20 each. Although I ordered left and right sensors, they sent two lefts. Since the sensors appeared identical other than the metal mounts, I installed both.

    Now I have new problems. I have no speedometer. Dash display stays at zero regardless of driving speed. Red BRAKE light has disappeared but the yellowABS and the yellow traction are still there. I also now have the yellow low tire pressure light on, even though I’ve doubled checked tire PSI and it’s between 33-35 psi. Factory specs for my tires. New pressure gauge, not the cheap one.

    After attempting to clear the warning lights by disconnecting the rear 12v negative mount to the body (2 minutes left detached), the warning lights went away then came back.

    I next did the blinking light ABS test and got codes 36 and 32. I again tried to clear the warning lights with the brake pedal pump technique, but warning lights returned.

    Any suggestions would be appreciated.
     
  2. ChapmanF

    ChapmanF Senior Member

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    Because brake system blink codes can appear on all three lights—ABS, VSC, and ((!))—and some of the codes overlap and mean different things, it is most useful to report blink codes with which light blinked each code.

    I'm going to assume your 36 and 32 were both on the ABS light, because both of those pertain to the left front wheel speed sensor.

    If you're confident in the sensor you installed at the left front, it would make sense to test its wiring next.
     
  3. Mdv55

    Mdv55 Active Member

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    Both those codes point to a front left speed sensor issue. A $20 sensor is much cheaper then most of the aftermarket options listed on Rock Auto and your problem most likely lies in that part.

    I'd clean and swap the old OEM sensors back in one by one, clear codes and test drive if you can. If the codes come back I'd look at better quality sensors before diving any further.
     
  4. ChapmanF

    ChapmanF Senior Member

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    And if that doesn't work, remember sensors are connected to wires, and wires can be tested too.
     
  5. dangerbag

    dangerbag New Member

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    Thank you all!

    Can the old OEM sensors be tested for voltage? Will a standard 12V reading mean the sensors are working?

    Before swapping old sensors with new, I cleared the codes twice by disconnecting the negative terminal of the rear 12V battery. Each time the ABS, the traction and the red brake warning lights came back.

    Thanks again.
     
  6. Mdv55

    Mdv55 Active Member

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    You already know how to read and clear blink codes, so them coming back are indicating there is still a problem that was never corrected or there is a new one introduced in the same area.

    The only things you're posting about that changed recently are the bearing, the sensor and possibly the wiring from the sensor connection back to where it connects to the car body as it may get tugged/jostled etc... during the repair process.

    A bad wheel bearing can interrupt the signal enough for them to trip a code. It's possible your sensors were fine and it was just the bearing that was bad.

    You replaced the bearings with what seems to be decent ones based on price point, so my focus wouldn't be there at the moment.

    You introduced a new variable with the cheap sensors though. The sensors vary voltage with speed and a surprisingly small bit of contamination can effect them. I had intermittent issues with the car that cleaning the sensor on the affected wheel instantly resolved. You should be able to test new and old for continuity easily enough..

    It should be also be easy enough to swap the old one back in without much effort. The fact the car doesn't read speed at all now leads me to believe that the info is either so bad from the sensor it throws it out or that the info isn't getting from the wheel hub to the ECU. This is most like due to an issue within the sensor itself or with the wiring that carries that signal.

    Given the price point of the sensor purchased compared to most of the other aftermarket options, that is the first thing I would rule out in a diag process at this point.
     
    #6 Mdv55, Oct 21, 2021
    Last edited: Oct 21, 2021
  7. dangerbag

    dangerbag New Member

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    Cleaning sensors is done how? With electronic cleaner or compressed air.

    As a note, the problem has evolved. I still haven’t had time to swap the new cheap sensors for the old or test the old for continuity.

    I have been driving the car though. Yesterday while driving home, the check engine light came on suddenly for no discernible reason and “Check Hybrid System” display. Worried I had a fluid leak or an oil pan leak, I quickly exited the freeway to investigate. Shortly after exiting the car literally stopped. I lost power steering and all engine compression. I shut the car off, investigated fluids, and then restarted the car.

    After driving .2 miles further I pulled into a safe area and jumped the code reader inputs so I could do a hard reset of the computer.

    Although the check engine light and the Check Hybrid System displays stayed on, the car drove fine. I was able to drive a steep grade to get home the final 30 minutes with no obvious mechanical issues.

    The plot thickens. Thank you for all your helpful insights.
     
  8. Mdv55

    Mdv55 Active Member

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    I used brake cleaner and a rag.
     
  9. dangerbag

    dangerbag New Member

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    Are the abs sensors active or passive? In other words can a continuity test be done when the sensor is removed from the car’s charging system?
     
  10. dangerbag

    dangerbag New Member

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    Update

    Replaced cheap $20 sensors with $50 sensors. Problem still persists. Put the OEM sensors back.

    I’ve been told I can pay to have a more detailed code reader check my codes. Is the expense worth it?

    Or is it cheaper to go with OEM new at $300 per sensor.
     
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