ABS sensor or did I knacker the wheel bearing or ...?

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fnlchris

Member
Posts
11
Location
Totnes, Devon UK
First post for me - my beloved Freelander TD4 is old - 2003 and bits are beginning to wear out. I've been running it mondo for many years and when the rear wheel bearing went I decided to remove the rear diff and drive shafts as well to make changing it easier; no need to remove the whole hub then. Job done without a bearing press with careful hammering. Found this thread very useful https://www.landroverblogger.com/how-to-replace-a-wheel-bearing-on-a-freelander

First drive and I got the 3 amigos came on only once I got the car rolling, nothing at start up. I have taken the ABS sensor out hoping it was just that or some of the graphite grease I used to ease the bearing in being squeezed out and upsetting things. It was covered in grease down there, so I have cleaned it out as best I can

I would like your expert opions before I replace it. I am not a mechanic, just a fairly capable DIYer, so please don't use any complex jargon, especially when it comes to electrics, now there I am an absolute beginner!

What resistance should the sensor show on the meter? I have seen quoted in other threads values between 950 and 1100 Ohms but I am not clear if they apply to the old style of ABS sensor or the new one or both. Mine is the new one - I believe the part number is SSW000020
I got a cheap replacement from fleabay and it is giving a similar reading to the one I took off - around 18.2 MOhms for the new one and 17.7 MOhms for the old one

Did I knacker the sensor, is the fleabay sensor any good, is it likely that graphite grease was interferring with its function or have I knackered the magnetic ring on the bearing?

The car has done nearly 200K miles and the turbo is gradually fading so I don't want to throw money at it but I am still very fond of it and would love to give it another year or two of life :)

Appreciate any help, thanks (I'm near Totnes in Devon)
 
As you have the post 2002 ABS set up, the bad news I am afraid is that there is a right and a wrong way to fit the bearing. The 'seal' on the edge of the bearing contains the ABS magnets and needs to be nearest to the ABS sensor.
As you have changed the bearing, I would guess it is unlikely to be a sensor fault, more likely you have either used a pre-2002 bearing (they do fit - but ABS magnets are not present) or you have used the correct bearing and fitted it the wrong way around so that the magnets are not on the ABS sensor side.
RAVE workshop manual says this....................(about the 2002 +)

An active ABS sensor is installed in each of the four wheel hub carriers to provide the ABS ECU with a speed signal
from each road wheel. Each of the ABS sensors is positioned in close proximity to the inboard seal of the related wheel
bearing and secured with a bolt. The seals, which rotate with the wheels, each contain a magnetic element
incorporating 48 pole pairs.

If you can find the part number of the bearing we can have a look to see if it is the right one.
As there is no ABS fault on start up, these are active sensors and are part of the self test, it is unlikely to be the sensor. Start with a check of the bearing type.
 
I know its unlikely to be something else in the system, but have you checked the diagnostic codes to make sure it is something to do with that wheel!

It might be something else, or even the wire got damaged on the other side when you took the driveshaft away (I presume you split it at the outer CV).
 
I've thought of an easy way to see if the bearing is in right way and sensor works!
Multimeter on mV ac connected to sensor and spin wheel. Should see voltage produced as magnets pass by the sensor.

If no signal change sensor, if still no signal then bearing may be wrong one or inside out!!

Saves taking it apart for fun!!
 
I would compare results with one or more of the other wheels if you try this ^^^. The older ABS system used simple passive sensors which would output AC, whereas the newer ones might be two-wire Hall sensors which require a power supply.
 
I would compare results with one or more of the other wheels if you try this ^^^. The older ABS system used simple passive sensors which would output AC, whereas the newer ones might be two-wire Hall sensors which require a power supply.
 
I know its unlikely to be something else in the system, but have you checked the diagnostic codes to make sure it is something to do with that wheel!

It might be something else, or even the wire got damaged on the other side when you took the driveshaft away (I presume you split it at the outer CV).

I cut the drive shafts in half and then split the outer CVs. It didn't involve putting any strain on or going anywhere near the ABS cables though as it was all done in situ
thanks for the thought though
 
I know its unlikely to be something else in the system, but have you checked the diagnostic codes to make sure it is something to do with that wheel!

It might be something else, or even the wire got damaged on the other side when you took the driveshaft away (I presume you split it at the outer CV).

I cut the drive shafts in half and then split the outer CVs. It didn't involve putting any strain on or going anywhere near the ABS cables though as it was all done in situ
thanks for the thought though
 
I would compare results with one or more of the other wheels if you try this ^^^. The older ABS system used simple passive sensors which would output AC, whereas the newer ones might be two-wire Hall sensors which require a power supply.
Thanks Andyfreelandy and Guineafowl21
The sensors have only 2 wires - so if they are Hall sensors, does that mean that Andyfreelandy's suggestion of spinning the wheel is not going to work because they need a power supply?
 
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