I still say the hub is faulty.

On 25/04/2021 at 20:31, UrbanPanzer said:

I still say the hub is faulty.

Until the last bit of messing around, when I seem to have completely broken the cable, the signals from NSF and OSF were identical apart from an intermittent, irregular drop in the OSF signal. It wasn't regular or frequent enough to be a missing part of the ABS ring in the bearing, and looked very much like a dodgy contact. Replacing the cable (as suggested earlier, splicing a "new" end from a breaker into the existing feed/return cable) will be much easier than replacing the bearing so is the obvious thing to try next.  

 

Separately, Skoda had a look at the car this morning and they reckon the droning/moaning/rumbling/whatever noise is all tyre related. Not sure I agree entirely, but they have stated in writing that there's nowt wrong with the wheelbearings, driveshafts or diff bearings. The tyres all have about 4mm left so I guess it's down to how many miles I want to throw away. One thing's for sure, I won't be buying Toyo Proxes next time.

On 23/04/2021 at 09:34, KenONeill said:

Not being funny but have you tried an olde-fashioned "rock test" for wheel bearing wear? Based on discussion so far, starting with the OSF.

Hi Ken,

Yes, I tried that, and no signs of rock or play. The car went through the MoT a couple of months ago (while the noise was present) with no problems then.

On 25/04/2021 at 19:43, mrgf said:

Out of pure curiosity, Narrowboat-Ian, have a try of driving the car so the ABS is on, switch off the key (In a nice safe place) For a few seconds, then turn it on again, so the engine re-starts the car, not the key/starter motor. Then see if the light goes out at least for some time or if it stays on as soon as you turn on again, if you get my drift!

 

Kind of bump-starting the car, after initial driving.

I don't want to sound obtuse, but not sure what this would achieve.

I have plugged into the OBD port and even been able to produce graphs of the speed readings being seen at the OSF/NSF sensors, and there was a clear intermittent fault in the OSF reading. The fact that in between the faults the readings matched those from the NSF, to me negates Panzer's suggestion that the rotor in the bearing could be at fault**, and points instead to a fault in the sensor or the connection to it.

I then detached the wiring plug, cleaned and reconnected it - and now there is no reading at all from the OSF sensor. The plug and sensor contacts are very, very clean and in good condition, so I doubt it's the connector. But someone previously has detached the plug, threaded it via a circuitous route that bends the wiring tightly around the hydraulic hose and I suspect that's crimped and damaged the cables, and my subsequent action in detaching and reattaching it may have actually finally broken one or other of the two wires.

** the rotor in the bearing is a simple plastic ring with metal inserts, it rotates with the hub and the metal inserts, when they pass the sensor, generate a current in the sensor (Hall effect) - the frequency of the signal indicates the rotational speed of the hub. The ring itself therefore is a very simple component that can't 'go wrong' 

27 minutes ago, Narrowboat-Ian said:

I suspect that's crimped and damaged the cables, and my subsequent action in detaching and reattaching it may have actually finally broken one or other of the two wires.

Well, the obvious answer in that case is to continuity check the cable surely?

13 hours ago, Narrowboat-Ian said:

Until the last bit of messing around, when I seem to have completely broken the cable, the signals from NSF and OSF were identical apart from an intermittent, irregular drop in the OSF signal. It wasn't regular or frequent enough to be a missing part of the ABS ring in the bearing, and looked very much like a dodgy contact. Replacing the cable (as suggested earlier, splicing a "new" end from a breaker into the existing feed/return cable) will be much easier than replacing the bearing so is the obvious thing to try next.  

 

Separately, Skoda had a look at the car this morning and they reckon the droning/moaning/rumbling/whatever noise is all tyre related. Not sure I agree entirely, but they have stated in writing that there's nowt wrong with the wheelbearings, driveshafts or diff bearings. The tyres all have about 4mm left so I guess it's down to how many miles I want to throw away. One thing's for sure, I won't be buying Toyo Proxes next time.

 

My continentals were VERY noisy....the goodyears on the front are much quieter.

2 hours ago, KenONeill said:

Well, the obvious answer in that case is to continuity check the cable surely?

Well, yes. The challenge being to find the other end of the cable! That's my next job.

On 23/04/2021 at 06:53, Wino said:

No intermediate connector unfortunately. Direct to connector at ABS module:- pins 1 and 2 at wheel sensor to pins 6 and 18 respectively at module. 

I'd be tempted to harvest connector plus a wheel-archful of wire from a scrappie car and cut and shut that in, waterproofing connection area well.

 

2 hours ago, UrbanPanzer said:

 

My continentals were VERY noisy....the goodyears on the front are much quieter.

From about 20mph I have a loud, low frequency rumble, then overlaying that is a throbbing noise at around (at a guess) 15ish hertz, which continues and gets a bit louder. I particularly notice the throbbing noise as I slow down for roundabouts etc.

There's no obvious vibration,

I recently swapped fronts and rears round; the fronts have 5mm of tread and the rears are on 3mm, so a halfway stage might be to put the current fronts back on the back of the car and get a pair of something different on the front, that would (hopefully!) quickly show how much of it is actually down to the tyres themselves.

7 minutes ago, Wino said:

 

It's one think knowing what the wire connects to, actually finding the blasted thing is another matter! It's buried somewhere under the air box... I think! 

Ah I see what you mean,  vertically below engine ECU I think.  Be careful disconnecting, I seem to remember someone saying that the cable latch is tricky or unintuitive or something. Never undone one personally.

 

I was suggesting my suggestion as I have a sometime fault that can flick up the abs quite regularly and then, not at all for some time. It seems that if it does come on and I try this method, it then stays off longer so there was a reasoning behind what I asked, if not a solution. I have had the sensor replaced more then twice and it stayed a =way a while but returned and then took it to a reputable specialist, who told it it was the sensor, despite my telling them I had swapped it out twice, (Thats three sensors) Only to have the fault return. They charged me around £200 to say it WAS but on the route home, up popped the and light. Back again they then said they swapped the bearing from left to right, (Would have just been easier to pop a new left one in) But the fault still showed, they then did a continuity test, nothing showed, leaving them to say it could only be the abs pump/module (£1000 new, £300 recon). In the coldest of weather, the abs light stayed off, coming back on again recently and for a while, quite frequently but now, just on the odd occasion, all with no extra work undertaken since! I find if it comes on, I switch off for a few seconds, turn the key, the car fires up (Bump start) Then the abs light stays off for sometimes, quite a time. (Weeks, rather then hours). So, like I said, have you had a little try? Unless you shunt in to another motorist, what have you got to lose?

22 hours ago, mrgf said:

I was suggesting my suggestion as I have a sometime fault that can flick up the abs quite regularly and then, not at all for some time. It seems that if it does come on and I try this method, it then stays off longer so there was a reasoning behind what I asked, if not a solution. I have had the sensor replaced more then twice and it stayed a =way a while but returned and then took it to a reputable specialist, who told it it was the sensor, despite my telling them I had swapped it out twice, (Thats three sensors) Only to have the fault return. They charged me around £200 to say it WAS but on the route home, up popped the and light. Back again they then said they swapped the bearing from left to right, (Would have just been easier to pop a new left one in) But the fault still showed, they then did a continuity test, nothing showed, leaving them to say it could only be the abs pump/module (£1000 new, £300 recon). In the coldest of weather, the abs light stayed off, coming back on again recently and for a while, quite frequently but now, just on the odd occasion, all with no extra work undertaken since! I find if it comes on, I switch off for a few seconds, turn the key, the car fires up (Bump start) Then the abs light stays off for sometimes, quite a time. (Weeks, rather then hours). So, like I said, have you had a little try? Unless you shunt in to another motorist, what have you got to lose?

"Unless you shunt it into another motorist" Umm, yeah. 

Intrigued at the "swapped the bearing from left to right" bit - you do know, don't you, that when you pop the bearing you break the retaining circlip? More to the point, did they?

I can't see why your switch off/coast/bump-start approach would work, though I am sure you're sincere :-) so I will keep in mind...

On 29/04/2021 at 13:03, Wino said:

Ah I see what you mean,  vertically below engine ECU I think.  Be careful disconnecting, I seem to remember someone saying that the cable latch is tricky or unintuitive or something. Never undone one personally.

 

I've had plenty of problems with the latching connectors on VAG wiring. However, (to give it its due) the one on the OSF ABS sensor released easily enough - fat lot of good that did me, though!  

4 minutes ago, Narrowboat-Ian said:

Intrigued at the "swapped the bearing from left to right" bit 

Pretty sure his was a rear bearing. Considerably easier to swap around.

 

 

1 minute ago, Wino said:

Pretty sure his was a rear bearing. Considerably easier to swap around.

 

 

Aaaaaah, I missed that - mea culpa.

Yes, you can swap the rears round though I do agree (particularly when you consider how cheap they are) that it would have been just as sensible to simply pop a new one on

19 minutes ago, Narrowboat-Ian said:

I can't see why your switch off/coast/bump-start approach would work

I can't see what it will achieve either, other than starting the car without the use of the battery or starter motot.

No, I understand the bafflement but in my instance, it does seem to have prolonged the interval where the ABS light illuminates again. Might be just luck or might be surging a little boost through the cabling or something or re-setting, as does a new start, the ABS system but it has helped! I do this procedure all without touching the clutch, BTW. Turn off a few seconds, turn the key so as the engine re-starts the car, ABS goes back off and stays off. I am only making a suggestion of trying it as it has sort of slowed down the re-occurance of my own issue and the next stage was to replace the module, on a vehicle I have to sell come October, due to the Ulez one expanding and on top of having just replaced the clutch.