Hi,
I've been hijacking another thread for a while about wheel bearing replacement but I thought it best now to start a new thread. Anyway, I had to replace my front wheel bearing and used an SKF bearing kit from Euro Car Parts not realising MB now sell the bearings separately rather than the entire hub assembly. After refitting everything I have an ABS inoperative warning when the car gets up to about 10mph. It clears when the ignition is turned off and on again but then comes straight back when you reach about 10mph.
I suspected the problem was that I'd either damaged the magnetic hub bearing seal by tapping it in with an aluminium tool or it was just a poor pattern part from SKF so I replaced the seal again with a genuine MB part and extremely carefully pressed it in with a block of wood and large vice. The ABS fault still comes up. So I'm now pretty sure that the problem is that the gap between the hub assembly and the speed sensor pickup is too big due to some small difference in the profile of the new bearing or bearing race position/size. I noticed that the clamp bolt for the wheel bearing nut is in a different position to where it was before I changed the bearings so this makes me think the dimensions on the new ones isn't exactly the same.
Before I throw in the towel and buy a new hub assembly for £190 I want to just double check that I haven't just got a defective sensor caused perhaps by a bit of strain on the cable when I removed the brakes to do the wheel bearing or just a pure coincidence. It seems unlikely but I would like to check it before wasting any more money.
Now I've removed the inner wheel arch liner and tested the ABS sensor with a mutlimeter. On resistance it measures 4.5Mohms or 6.5Mohms depending on which way round the test leads are connected. That makes me think it is probably some kind of hall-effect sensor rather than a coil pickup so I tried measuring on diode test mode and it measured 0.6V or 1.6V depending on which way round the test leads are connected. It's very fiddly to connect the test leads so I wasn't able to try measuring voltage with the wheel spinning etc.
Does this sound correct? The only way I can think to know for sure is to check the one on the other wheel but I don't particularly want to have to strip out the wheel arch liner on that one too. Is there any other test I can do before I re-assemble the wheel arch liner and buy the new hub bearing assembly? I would imagine that the ABS inoperative fault would come up immediately (i.e. before the car starts moving) if there were a broken wire. I don't have access to STAR diagnostics but given that this fault occurred immediately after the wheel bearing work I think it has to be the cause.
Many thanks
I've been hijacking another thread for a while about wheel bearing replacement but I thought it best now to start a new thread. Anyway, I had to replace my front wheel bearing and used an SKF bearing kit from Euro Car Parts not realising MB now sell the bearings separately rather than the entire hub assembly. After refitting everything I have an ABS inoperative warning when the car gets up to about 10mph. It clears when the ignition is turned off and on again but then comes straight back when you reach about 10mph.
I suspected the problem was that I'd either damaged the magnetic hub bearing seal by tapping it in with an aluminium tool or it was just a poor pattern part from SKF so I replaced the seal again with a genuine MB part and extremely carefully pressed it in with a block of wood and large vice. The ABS fault still comes up. So I'm now pretty sure that the problem is that the gap between the hub assembly and the speed sensor pickup is too big due to some small difference in the profile of the new bearing or bearing race position/size. I noticed that the clamp bolt for the wheel bearing nut is in a different position to where it was before I changed the bearings so this makes me think the dimensions on the new ones isn't exactly the same.
Before I throw in the towel and buy a new hub assembly for £190 I want to just double check that I haven't just got a defective sensor caused perhaps by a bit of strain on the cable when I removed the brakes to do the wheel bearing or just a pure coincidence. It seems unlikely but I would like to check it before wasting any more money.
Now I've removed the inner wheel arch liner and tested the ABS sensor with a mutlimeter. On resistance it measures 4.5Mohms or 6.5Mohms depending on which way round the test leads are connected. That makes me think it is probably some kind of hall-effect sensor rather than a coil pickup so I tried measuring on diode test mode and it measured 0.6V or 1.6V depending on which way round the test leads are connected. It's very fiddly to connect the test leads so I wasn't able to try measuring voltage with the wheel spinning etc.
Does this sound correct? The only way I can think to know for sure is to check the one on the other wheel but I don't particularly want to have to strip out the wheel arch liner on that one too. Is there any other test I can do before I re-assemble the wheel arch liner and buy the new hub bearing assembly? I would imagine that the ABS inoperative fault would come up immediately (i.e. before the car starts moving) if there were a broken wire. I don't have access to STAR diagnostics but given that this fault occurred immediately after the wheel bearing work I think it has to be the cause.
Many thanks
