ABS/Brake light on after wheel bearing replacement

Hi Brian,

Yes, there is a speed sensor that is mounted to the front strut. It would be reasonable to remove the left front tire and inspect the speed sensor to see if it was properly reinstalled (compare to the right front speed sensor if necessary.)

You might also disconnect the negative 12V auxiliary battery terminal for a few minutes then reconnect, to see if that will clear the warning light. The repair manual does not indicate that initialization or calibration is required when a front hub is replaced.

If you find nothing wrong, then it is reasonable to consult with your dealer regarding the warning light and the brakes pulling to the right. You may also want to have the front wheel alignment checked after this repair is completed.

 

Keep us posted about the cause.

 

Hi Brian,

techinfo.toyota.com

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To get you started, I attached an exploded parts diagram of the front hub.

 

The speed sensors connect to the skid control ECU, located behind the dashboard.

One way to test a sensor is to use the Toyota Hand Held Tester to verify proper operation. Another way to test it is to hook up an oscilloscope to the sensor output, drive at 19 mph, and look for a 4V peak-to-peak sine wave display. The period of the sine wave is ~6 ms.

At this point I think that taking your car to the dealer is your best bet. I'm interested to hear what DTC were logged and the diagnosis.

 

I replaced this exact wheel bearing at about 100,000 miles. Got the hub assembly from a Toyota dealer in Texas, Hoy Fox or something like. (Great deals on parts 1/3 the price of the local dealer).

It definetly sounds like a sensor problem. The computer thinks your left side wheel has stopped, so it won't let the friction brakes engage. (Just a theory). One thing I noticed was that when re-installing the dust cover you had to be extremely careful in its placement or it would interfere with the wheel speed sensor.

 

Thanks for the update; it is interesting that your disconnecting the 12V battery did not reset the skid control ECU. Maybe the brake power supply also had to be disconnected to effect a reset?

 

Hello, I am having literally this exact same issue! I d/c'ed the battery to no avail, BUT i will try it again tomorrow and leave it d/c'ed for a good 10 minutes. I am just wondering if btrotter is still around or if anyone can explain to me what means by it needs to be "Reset" ? is it just the computer that needs to be reset so the lights go away and it recalibrates?


So my story :

My mechanic today replaced my front right bearing. as i drove away from the garage, the VSC , abs and (i) orange light came on. Car drives ok no issues ..though my mechanic said to bring it in and he will look at the sensors. I am worried i have to change out a speed sensor and i hope it wasnt damaged. Given that the car drives well enough, I am thinking it just a calibration issue...any thoughts/ideas on this? its just so frustrating! Maybe take it to the dealer and have them check it? if it needs a special tool to reset?


also : maybe ride is a bit rough/stiffer? but overall drives just fine, brakes, etc ok. Maybe i did not notice the ride quality as the drone of the worn bearing was too much. but it goes, stops, engages battery without issue.

 

One thing to keep in mind is alignment of the dust cover behind the wheel bearing hub. The steel portion of the dust cover has a small oval shaped window/slot cut into it to allow the speed sensor to 'look' through. If this slot is not properly aligned with the speed sensor, then you end up with steel between the sensor and tone wheel instead of an air gap. The speed sensor will not function. Kind of like putting a piece of cardboard on the end of a flashlight.

 

Thanks ! I hope that’s it . Taking car back to mechanic and I will tell him about the dust cover - and to check that first ... will report back with updates ...

 

So here is the update - hopefully this will benefit the users here:

So it seems like the 10mm bolt on the sensor rotted away (or maybe it broke?)...dust cover was ok but the sensor was not aligned and not in all the way. So they used some silicone to further enforce it when it was in - hopefully that will hold, otherwise will take it back and get it fixed again....

but lights are now gone and car runs great! and so quiet (even for a prius) after the noisy bearing was fixed.

so in the end TMR-JWAP was right - it was a sensor issue. thanks everyone!!!

 

This seems like a good place to mention, for future reference, that there is a speed sensor test mode that is, by design, more sensitive than the checks the ECU does in normal operation to set warning lights. You find a place where you have a straight path to drive for a certain distance at a certain speed, call up the test mode, then accelerate and drive straight for the required distance and stop, and the computer tells you whether everything is good with all the speed sensors.

And the manual instructs to perform this test as the finishing step of any work on the bearings, etc. The whole idea is so nobody completes a bearing job and then gets a warning light driving away with some surprise discovery of a wheel sensor problem.

Show me a mechanic who has to have the car driven back with a warning light to discover the sensor problem, and I'll show you a mechanic who skipped the step laid right out in the ding-binged manual.

-Chap