ABS Sensor

[HarryM1BYT]

Originally Posted by Master

Harry my neighbour is an AA man & he plugged his diagnostic computer into the car & when i spun the wheel it was registering on the computer so i have to assume it was picking up the pulses...The front passenger side is the only one that is working its self

Checking it produces pulses, is simply not enough - it might well produce pulses but miss out the odd one or two at low speeds, which is enough to cause the ABS to cut in. Your AA man may not have understood that?

The wheel has to be jacked up, a meter or the gadget I devised (see in my sig block) connected then the wheel very slowly turned and the tyre marked where the pulses occur.

If the pulses are being produced as they should, the marks on the tyre will be evenly spaced at around every two or so inches around the full circumference of the tyre, with none absent and no extra ones.

[Jakg]

Originally Posted by Stickman

Just out of interest can a t4 determine which sensor is faulty as I have the abs light activated on my club ?
Regards
Chris

Yes - if the car has detected a fault it should have stored in which corner its in which can be read by T4 / TOAF and perhaps other diagnostic tools. Whether its the hub or sensor though, is another matter.

[HarryM1BYT]

Quote:
Originally Posted by Stickman
Just out of interest can a t4 determine which sensor is faulty as I have the abs light activated on my club ?
Regards
Chris

Yes - if the car has detected a fault it should have stored in which corner its in which can be read by T4 / TOAF and perhaps other diagnostic tools. Whether its the hub or sensor though, is another matter.

Originally Posted by Jakg

Yes - if the car has detected a fault it should have stored in which corner its in which can be read by T4 / TOAF and perhaps other diagnostic tools. Whether its the hub or sensor though, is another matter.

T4 can generally only register a hard fault, one where the ABS light remains on. T4 cannot register a fault if its an occasional missed pulse at low speed causing the ABS to kick in.

[EastPete]

Car is all back together now, and back on the road - the ABS seems fine. No lights coming on, and when I try an emergency stop, I can feel it cut in. For the after-market sensor, even though the measurements seemed the same as the Rimmers genuine sensor, when I fitted it (after filing down the barrel of it a bit to get it go into the hole in the hub) it did not seem to reach completely over the reluctor ring, so I removed it and filed a bit off the mounting bracket so it went a bit further into the hub.

Pete

[HarryM1BYT]

Just to add a bit to the thread, the actual sensor inside the plastic, is likely quite similar to this - http://uk.rs-online.com/web/p/hall-e...nsors/8223771/

There are two general types of sensor, one which supplies an analogue value back dependant on the magnetic field strength and one which simply switches on or off, as it comes near a magnetic field. Our sensor uses the latter type, on or off.

As the dimensions of the OEM and after market items outer casing seem quite close, I suspect the actual sensor inside may not be deep enough in the plastic outer casing, or the component orientation is a touch out - hence filing a bit off the mounting bracket seems to usually work.

All they do is switch on and off, as each magnetic pole passes them rather like a reed switch, except a reed switch could not operate at the speeds needed, nor with the reliability.

[Dragrad]

Thread moved to a more appropriate forum. Re-direct left in old. This may be the better forum as threads get ‘lost’ very quickly in the General Forum.

[MWMan]

Went up to Gateshead this weekend to collect a new bonnet for my Tourer, and for the first time ever, I had an ABS fault come up while travelling up there. Just read this thread and it has helped me immensely. I followed the testing procedure using the multi meter and located the fault to the rear off side. Fitted a new sensor from DMGRS and all is now well. Thank you all.

In the spirit of passing on a few learning experiences here is what I did on the Tourer.

1. There was no way the sensor was coming out of the hub, but having read a few posts on drilling it out, I was a bit concerned about catching the ring on the bearing , and also swarf left inside the hub. So, I removed the hub and bearing to gain access to the sensor. I then drilled it out with a 10mm drill (the hole is 12mm), and then cleaned it out with a file until the sensor fitted freely down the hole. Then I vacuumed out all the swarf.





2. I thought removing the sensor from the hub was going to be the worst part, but in fact getting the Blue connector from under the seat, to go through the hole in the body was the worst. I assume it is the same on all Tourers, but with the seat swab removed, I could feel an insulation pad at the base of the back seat, that was sitting over the whole / cable. I had to chisel away at this with a screw driver (not easy as it was all by touch, as I couldn't see anything) until I got enough space to get the Blue connector through. Feeding it back through again was even worse, but I finally managed to get it through.



3. EastPete had shown some measurements for the front ABS sensors in the thread, So I thought I would show the length of the rear ones for future reference. The sensor was from DMGRS, and was 32mm.

[David Lawrence]

Originally Posted by EastPete

Car is all back together now, and back on the road - the ABS seems fine. No lights coming on, and when I try an emergency stop, I can feel it cut in. For the after-market sensor, even though the measurements seemed the same as the Rimmers genuine sensor, when I fitted it (after filing down the barrel of it a bit to get it go into the hole in the hub) it did not seem to reach completely over the reluctor ring, so I removed it and filed a bit off the mounting bracket so it went a bit further into the hub.

Pete

Pete,

I fitted one of the dmgrs front sensors yesterday. Had 2 problems fitting it, one was the electrical connector was very tight, now got that in ok but was certainly hard to fit compared with oem.

Second issue was getting the sensor all the way down. It seems slightly raised to me. The fixing bolt is tight but the shank of the sensor is slightly proud. I can get my finger nail under the fixing tab at the sensor end of it.

I suspect i will have to take it out again and file it down as you did. Annoying thing is after fitting initially i drove over 100 miles with no issue. No idea why it could behave quite like that.

How did you file yours down? Was it just the fixing plate or did you file some of the shoulder at the tip end as well?

[EastPete]

Originally Posted by David Lawrence

Pete,

I fitted one of the dmgrs front sensors yesterday. Had 2 problems fitting it, one was the electrical connector was very tight, now got that in ok but was certainly hard to fit compared with oem.

Second issue was getting the sensor all the way down. It seems slightly raised to me. The fixing bolt is tight but the shank of the sensor is slightly proud. I can get my finger nail under the fixing tab at the sensor end of it.

I suspect i will have to take it out again and file it down as you did. Annoying thing is after fitting initially i drove over 100 miles with no issue. No idea why it could behave quite like that.

How did you file yours down? Was it just the fixing plate or did you file some of the shoulder at the tip end as well?

I didn't file the tip end at all - best to leave this alone in case you damage the sensor. I filed the outside of the main 'barrel' body of the sensor so it would fit into the hole, and also took about 1mm off the steel bush that goes into the bolt hole on the mounting bracket/flange part of the sensor, so the sensor would go slightly further into the hub. I would only use genuine Rover items in future - it is worth the extra 20 quid to avoid these issues with aftermarket items

Pete

[David Lawrence]

Originally Posted by EastPete

I didn't file the tip end at all - best to leave this alone in case you damage the sensor. I filed the outside of the main 'barrel' body of the sensor so it would fit into the hole, and also took about 1mm off the steel bush that goes into the bolt hole on the mounting bracket/flange part of the sensor, so the sensor would go slightly further into the hub. I would only use genuine Rover items in future - it is worth the extra 20 quid to avoid these issues with aftermarket items

Pete

I just removed it and did as you described. My problem seems to be that the sensor is gounding out on the shoulder at the bottom of the hole, and i can tap it down but it wont stay down. The light stayed out for about 15 minutes of mixed driving then came on again. Wondering if a big washer under the fixing bolt head might keep it pressed down in the hole better as there is just too much flex in the plastic mounting bracket, its never going to stay down for long.

At least it confirms the diagnosis that the sensor is not getting far enough in to get a reliable signal for long