ABS light on after new wheel bearing/hub ?

[69buick]

Hello,
Just replaced my front wheel bearing and new hub on 06 Mazda 3. We did carefully remove the ABS sensor from the knuckle as not to damage it while pressing out the old hub and old bearing and installing the new ones. The ABS light came right on after replacing the two parts. The wiring is fine to the ABS sensor. What I don't understand is how the ABS sensor that attaches to the knuckle gets its signal triggered. I don't see anything in the old bearing or old hub that would provide a signal to the ABS sensor as the wheel rotates. I checked this carefully after seeing that autozone specifies two different hub/bearing assemblies depending on whether you have ABS or not. This implies there is something that triggers the ABS sensor mounted in the bearing or hub so I was thinking perhaps we installed the wrong parts. FYI - Autozone does not sell just the bearing or hub separately you buy the hub with the bearing pressed on. Is there something inside the CV drive axle that triggers the ABS light?

We used C236-33-060A hub and BBM2-33-047 Bearing both Mazda part #'s.

Any input /suggestions appreciated

Thanks

 

[TheMAN]

the bearing has magnetized spots on one side... if you installed it backwards then there's your answer why your light came on

 

[69buick]

the bearing has magnetized spots on one side... if you installed it backwards then there's your answer why your light came on

Thanks for the reply,
Didn't know about that. I would have suspected some kind of label on the new part to install one way only. Both sides looked the same so we figured it didn't matter. I didn't see a difference on the old bearing either. Are the magetized spots on the outside of the bearing or inside the bearing?

 

[69buick]

Watch your wheel bearing orientation

Good call "TheMAN". Just got back from Mazda dealer. Purchased another bearing and didn't notice it the first time around as I was not looking for it but one side of the bearing has a black ring on what I would call the dirt seal and the other side of the bearing is all steel one color. The black side is also magnatized and I was told by the service department to keep that black side facing out which would place the ABS sensor right next to it.

Now I wonder if my ABS light will go out on it's own after I install the new bearing correctly, or do I have to go to a dealer to have the ABS light reset?

Thks

 

[69buick]

Took everything back a part and yes I installed the bearing backwords. Installed a new bearing with the black ring towards the sensor. ABS light was still on after starting up the car but it went right out after I backed out of the driveway and went forward a few feet. Also now that the abs light is off my cruise control now works again.

As a side note I don't understand how the abs sensor is getting a pulse from the black ring on the outside of the bearing as the wheel spins. I have the black ring out on the bench removed from the bearing. The ring appears to be all magetized all the way around. I was expecting spots to be magnetized and other spots not to be magnetized so a pulse could be generated. I suppose if I had a gauss meter I would be able to detect differences of magnetic strength around that ring. Until then it's still a mystery on how it works.