How do the front ABS sensors work??

[Thatman]

Hi all. I'm new to the forum and I'm at my wit's end regarding the front ABS sensors on my 2009 T3 Hatch. B asically to cut the long story short, I'd like to know if the ABS sensor in the front wheels senses on the wheel bearing or if it senses on an ABS ring mounted on the outer CV like most other older cars? I am asking because I bought this car as a flip and when I bought it the digital speedometer wasn't working so I did some investigation and removed the sensor and peeked into the hole where the sensor mounts and saw that there was no ABS ring with teeth showing. Then I removed the entire shaft and realised that the outer CV did not have an ABS ring on it. So, before I conclude that the incorrect type outer CV was fitted to the car, I just want to confirm that these cars do indeed use a 48 tooth abs ring mounted on the outer cv and not a wheel bearing based sensor in the front.
I also noticed that there are a few different shaft and hub size combos for the same generation yaris. Does the ABS and non ABS option affect shaft size and hub spline count? Mine is a 26 spline hub and 22 spline shaft.

TIA. I'm in South Africa by the way if anyone's wondering.

[ex-x-fire]

Its in the wheel bearing, it magnetic. Only one side of the bearing is like that.

[Thatman]

Okay just so we're on the same page, the outer CV joint itself does not have an ABS ring. The Wheel bearing in the front is what triggers the ABS sensor? Could the dirt evident in the above picture cause a problem with sensing between the sensor and the bearing? And if there is a problem, is it definitely the sensor that fails and not the bearing? The bearing is not making any noises and appears to be perfectly fine. How often do the sensors themselves die out on average? I did a diagnostic scan and got an error on both the front wheels hence why I thought that the incorrect CV's were fitted. Is it possible that the incorrect bearings (non abs) were fitted? If so, is there a way I can check by visual inspection that the bearings are indeed the correct ABS compliant bearings? Thanks in advance the little that you have told me has helped a great deal. I was losing my mind because no one could give me a definitive answer.

[CrankyOldMan]

You can get a magnetic field sensitive film and put that on the side of the bearing shown in the pictures. Something like this: https://www.reddit.com/r/Justrolledintotheshop/comments/7a7cyx/i_used_a_magnetic_viewing_film_to_discover_a/

You should see a pattern around the bearing. No pattern = wrong bearing or installed the wrong way. The sensors themselves are very sensitive to mechanical damage when removing them, so if the bearings have been replaced before they might have been broken in the process. The sensors themselves are just a coil of wire encased in plastic--nothing to fail on them.

[Thatman]

I cleaned up the bearing and took a picture as attached. I don't see any magnetic looking ring here. Safe to assume that it's missing?

[Thatman]

Where could one be able to get the magnetic field sensitive film?

[Thatman]

I just googled the part number engraved on the bearing and it seems to indeed be an ABS equipped bearing. Perhaps indeed it was fitted incorrectly.Its bit hard for me because I don't even know what I am supposed to be looking for on the bearing to know if its on the right way or not.

[CrankyOldMan]

Where could one be able to get the magnetic field sensitive film?

No idea where you could get it locally but online you can pretty easily find it from the usual suspects: fleaBay, scamazon, etc.

[CrankyOldMan]

I cleaned up the bearing and took a picture as attached. I don't see any magnetic looking ring here. Safe to assume that it's missing?

I just googled the part number engraved on the bearing and it seems to indeed be an ABS equipped bearing. Perhaps indeed it was fitted incorrectly.Its bit hard for me because I don't even know what I am supposed to be looking for on the bearing to know if its on the right way or not.

The brown ring should have the magnetic material in it. I can see some striations in it that may correspond to the magnetization pattern.

[Thatman]

When I got the car, the speedometer (digital) wasn't working (still isn't) and the ABS and handbrake lights are on on the dash. When I scan the car I get codes for the two front wheel sensors and the rear right hand side one. Could the sensors themselves be faulty? I understand that the rear sensor is integrated into the hub so I have to replace the whole hub. Is there anyway to test the sensor using a multimeter perhaps? I'd hate to repace the sensors only to find that the bearings are the fault so if theres any way to narrow down the fault point I would highly appreciate it. Thanks for all that have contributed thus far you guys have been a great help.