ABS light on after wheel bearing replacement!

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by That_Prius_Car, Sep 11, 2015.

  1. That_Prius_Car

    That_Prius_Car Austin Kinser

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    Hello all, my 2006 Prius with now 68,000 miles just had both front wheel bearings replaced today from an independent shop in town with a good reputation. $625.00 after taxes.

    Anyways, after picking up the car and leaving at the end of the day, the ABS light came on. No other lights at all. Just the ABS. And then it turned off... Then came back on, now it's turned off again. Brakes feel different. Regen comes on like normal for the first few seconds of braking, then you can feel it cut out.

    Took it for another drive tonight and the ABS light is off again and the light didn't come back on in the 3 mile drive, but the regen still isn't normal, and on the drive, I applied normal pressure on the brakes at 50 MPH and the slip indicator flashed a couple times? So something isn't right.

    Any ideas before I take it to the shop in the morning? Pointers I can give my mechanic?
     
  2. xliderider

    xliderider Senior Member

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    Wheel speed sensor, or harness not connected properly to the wheel speed sensor? ABS and Traction Control rely on the wheel speed sensor to detect wheel slip and or lock up.
     
  3. That_Prius_Car

    That_Prius_Car Austin Kinser

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    Took it back to the mechanic this morning. He said its possilble the bad bearing caused the speed sensor to fail.

    My ABS light has not come back on but braking is still weird and regen is spotty. I was getting off and exit ramp today and applied the brakes with normal pressure at 60 MPH and the slip indicator light flashed a couple times as if it thought the wheel was slipping again.

    To make it worse, I thought I'd take the wheel off and clean the speed sensor myself, and the bolt holding in the sensor snapped off. It will probably have to be drilled out. Ugh.

    At my wits end.
     
  4. That_Prius_Car

    That_Prius_Car Austin Kinser

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    Update: ABS light and (!) light are on again. Taking it in soon to have the code scanned to see which speed sensor is bad, then I'll replace it.

    Another question. At speeds above 40 MPH, there is a constant LOUD humming noise. Louder than the old wheel bearings I just replaced. Definitely coming from the front of the car. The tires probably have about 30% tread left. They are the same crappy Nexen tires the dealer put on the car when I bought it. They're also directional. I already checked the arrows to make sure the mechanic didn't accidentally put the passenger side tire on the drivers side, switching the rotation. Could the bad front bearings have caused uneven wear in the front tires and now with the new bearings, be causing that noise because the wheels are nice and tight again?
     
  5. Lucifer

    Lucifer Senior Member

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    When I had Keene nh Toyota replace the front wheel bearings on my gen 2, they did a wheel alignment afterwards, when I had them do the front wheel bearings on my gen 3, they did a wheel alignment, both cars were silent afterwards, just say'in
     
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  6. That_Prius_Car

    That_Prius_Car Austin Kinser

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    Okay, so another update. Turns out the loud humming after the new bearings was actually a defective bearing. They installed another new one and bam, super quiet again.

    On the down side, the ABS lights were due to a bad ABS sensor, RF sensor read bad (according to them), and I had them order a new (aftermarket) sensor and install it. Got the car back today, and the ABS lights are off, but the braking still isn't normal. It regen's longer now, but still cuts out early as if I hit a pothole or a wheel lost traction. Though my traction control light isn't blinking or anything like it would sometimes before. I'm so fed up with this car.

    I need to figure out a way to see each individual wheel speed. I have a tablet with the Torque App and custom PID's. I just haven't found any PID's for speed sensors on the Gen.II.
     
  7. That_Prius_Car

    That_Prius_Car Austin Kinser

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    So another bump and update. Took the car back to the repair shop and he hooked a computer to the car and as expected, no codes. I don't even know if he checked each individual wheel speed when he drove it. But the regen is still kicking out at 15 mph vs 7-8 mph before the repair. I downloaded a speedometer app on my iPhone and checked, thinking the speed would be way off on the car, but it's normal. He offered to return the aftermarket ABS sensor and order a Toyota one and I can pay the difference, but now I'm not sure that's it.

    What could cause the regen to do this?
     
  8. goldfinger

    goldfinger Active Member

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    No codes, slightly less regen, 9 year old car. I would drive it for a few weeks and see if the car settles down. You got a really good price for two wheel bearings.
     
  9. That_Prius_Car

    That_Prius_Car Austin Kinser

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    Still not fixed. Haven't fixed itself either. Regen is still kicking out at 15 mph vs 7-8 mph before. When it kicks out at 15, there's a small lurch and if I lift off quickly and depress again, regen comes back on down to the normal 7-8mph.
     
  10. goldfinger

    goldfinger Active Member

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    That_Prius_Car, it does sound like anti-lock confusion. Its as if your car thinks the wheels are turning different speeds. Could you have a chipped tooth on one of the speed sensors? Do you get this behavior under both hard and easy braking conditions?
     
  11. That_Prius_Car

    That_Prius_Car Austin Kinser

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    When I'm braking harder than usual, it will regen down to the normal 7-8 mph but the transition from regen to friction braking is lurchier than I remember. Basically a full quarter second with no brakes when switching. Braking normally, the regen cuts out at 15-16 mph now, with that same lurch forward. No warning lights or traction control light flashing when it does this.

    The passenger side wheel speed sensor was replaced after the wheel bearing replacement with an aftermarket one. The left side is still original. I took it back to the shop and they hooked it up to this machine and drove around and looked at each individual wheel speed supposedly and said all sensors read correctly??

    Also worth noting, I tried to take off the drivers side wheel speed sensor to clean it, and the top part of the bolt snapped off. The sensor is still in sorta snug but does wobble a little. Maybe that's causing it?
     
  12. Patrick Wong

    Patrick Wong DIY Enthusiast

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    That certainly is not helping. You will have to have the remnants of the bolt drilled out so that a new bolt can be installed.

    Depending upon the size of the bolt, it may be possible to drill a small hole into the stud, then use a screw extractor (with a left hand thread) to dig into the hole and remove the stud.
     
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  13. goldfinger

    goldfinger Active Member

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    A certain speeds that change with tire wear your sensor is probably vibrating. This vibration could be causing missing and/or additional pulses. Driving at a constant speed your shop's test machine would read good. That's my theory anyway. Please report back when you fix this.
     
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  14. That_Prius_Car

    That_Prius_Car Austin Kinser

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    Ugh. Update. So three days ago, the ABS comes on, along with the ! Symbol. So we take it in and he reads the code, left front wheel speed sensor is bad. (I kind of expected it. I just replaced the right side sensor a couple months ago.)

    I was hoping this would fix the regen cutting out at 15mph vs the stock 7-8mph. Before any of this, the brakes were smooth and transition from regen to friction brakes at 7-8mph were unnoticed. Now it transitions at 14-15mph and the transition is a noticeable lurch as it switches.

    I just got it replaced this morning and it's only went 10 miles (to work.) I'm hoping it's something that clears up once it learns itself? Or if there will be no "learning itself" bracket and something's still off.

    Maybe I'll disconnect the 12v later tonight, turn it on and off a couple times and it will relearn itself.
     
  15. Gorhamax

    Gorhamax Junior Member

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    In hopes that it may help in the future, the ABS ECU can be “recalibrated” after installing new wheel bearings through Techstream. ABS ECU > Utilities > Test

    This may have been the necessary action to correct the OP’s problem.
     
  16. First_Time_prius_owner

    First_Time_prius_owner Junior Member

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    Did this ever get fixed for you?
     
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