18 replies to this topic

[2mondeos]

Hi all,

I have an '03 tdci - it needed 2 new rear wheel bearings to pass MOT and these were fitted a couple of weeks ago.

Now, the ABS is activating at low speeds at the end of the braking - it's very brief  but it's there. e.g. a 6 mile journey today - the ABS came on once - but on return journey it came on half a dozen times. When the ABS activates there is no warning light, just the braks pulsating for a second (if that). it's never had any ABS issues since I've owned it and it started the moment I left the shop after haviong the bearings replaced.

They are certain the new wheel bearings are fine, have been fitted correctly and the alignment is good for the sensors. They also replaced both bearings on once occasion, using a different supplier to rule out probs with bearing teeth etc.

It's a well respected local company, but the car has been with them 6 or 7 times over last couple of weeks and we're no further forward. It's had diagnostics run by at least 2 different places (one of them is a diags specialist).

Garage are trying their best, but I'm not mechanical at all so rely on them.

Has anyone had this sort of issue before and is there a checklist we can at least go through? If it's not the bearing, then is it a sensor not functioning, a wiring fault.

The fault is there, so why doesn't it come up on computer diags?

Thanks for your help.

[Gary Price]

Normally the bearings are fitted with new abs sensors?
Was this the case with the bearings they fitted?

I would normally suspect faulty sensors in the new bearings, but since they have changed both to another set of bearings this should have ruled this out.
Are the 2 sets of bearings form different manufacturers? They could be from different suppliers but form the same manufacturer.

Are they activating on one wheel or both?

It is possible the wiring is damaged, or water in the connectors.

[2mondeos]

Gary Price, on 17 November 2011 - 06:49 PM, said:

Normally the bearings are fitted with new abs sensors?
Was this the case with the bearings they fitted?

I would normally suspect faulty sensors in the new bearings, but since they have changed both to another set of bearings this should have ruled this out.
Are the 2 sets of bearings form different manufacturers? They could be from different suppliers but form the same manufacturer.

Are they activating on one wheel or both?

It is possible the wiring is damaged, or water in the connectors.

Thanks Gary.

Normally the bearings are fitted with new abs sensors?
Was this the case with the bearings they fitted?
I don't know but I can ask them tomorrow. I was only charged for bearings, so likely answer is no.

Are they activating on one wheel or both?
I don't know. It's hard to tell because it's brief - but it feels like the front driver side, strangely. A mechanic drove it today while I sat in passenger seat and I'm not sure he knew either, but he knew it was coming on.

Sorry this is vague and probably no help at all.

[stripe88]

thought they were sold with the sensors....go grab your old ones out of their bin...spares.  probably plugs just want a clean up...wd40.

[totalguy]

stripe88, on 18 November 2011 - 03:16 PM, said:

thought they were sold with the sensors....go grab your old ones out of their bin...spares.  probably plugs just want a clean up...wd40.

yes bearings are sold with abs sensors on them already. they sometimes come with bolts to bolt the bearing on sometimes you need to buy them seperate

[Bamso]

Hi

I live in Norway, and have a similar problem with my '02 estate 2.0 TDDi.  The problem startet after I had a garage to change all 4 brake discs.  ABS is activated in the same way as you describe.  In addition to that the brake pedal becomes very firm/hard sometimes, and the car requires a very hard pressure to the pedal before it stops.

I had a Ford dealer  to run a full diagnostic, without any result.  There are no fault codes. They also run the car with data logging on all four wheel, and all sensors seems to be operating as they should,

I would be very interested to learn if you have any progress with your car.

[PURPLE_2L_LX]

When they fitted new pads did they crack open a bleed nipple for the excess fluid to escape?

If not it can damage the seals in the ABS unit and the master cylinder.

How many miles have you done since?

[siruncle]

Bamso: i'm pretty sure you can get a reading off the sensors at the connectors under the back seat, using a multimeter, there's a few topics on this in this forum/section, as well as how to's.

the haynes workshop manual (book) for your car will have details of what readings to expect.

[woodsy133]

2mondeos, on 17 November 2011 - 06:27 PM, said:

Hi all, I have an '03 tdci - it needed 2 new rear wheel bearings to pass MOT and these were fitted a couple of weeks ago. Now, the ABS is activating at low speeds at the end of the braking - it's very brief but it's there. e.g. a 6 mile journey today - the ABS came on once - but on return journey it came on half a dozen times. When the ABS activates there is no warning light, just the braks pulsating for a second (if that). it's never had any ABS issues since I've owned it and it started the moment I left the shop after haviong the bearings replaced. They are certain the new wheel bearings are fine, have been fitted correctly and the alignment is good for the sensors. They also replaced both bearings on once occasion, using a different supplier to rule out probs with bearing teeth etc. It's a well respected local company, but the car has been with them 6 or 7 times over last couple of weeks and we're no further forward. It's had diagnostics run by at least 2 different places (one of them is a diags specialist). Garage are trying their best, but I'm not mechanical at all so rely on them. Has anyone had this sort of issue before and is there a checklist we can at least go through? If it's not the bearing, then is it a sensor not functioning, a wiring fault. The fault is there, so why doesn't it come up on computer diags? Thanks for your help.

i have just had a similar problem, i have just changed a rear wheel bearing, but at the same time i changed all four discs an pads, i initially thought that i had not bled the braking system properly. anyway like you said it was at the very end of braking at really slow speeds. i had diagnostics done and nothing flagged up. At this point i suspected a faulty sensor on the new wheel bearing. I took the whole thing back to local motor factors and they changed it under warranty.Put new one on and hey presto no more problems with it.
i thought it was strange that nothing came up on diagnostics though.
anyhow just a heads up to anyone else who encounters this problem.

[scratch golf]

mine has been doing it for weeks,my mate owns his own garage so i tok it to him,he had a look and before he put it on the ramps he said it was abs ring,all 4 would have to be checked to find the culprit,but he said it was nothing major.

[Dontellimpike]

Hi Guvnors,
I joined tonight. Hello all. I hope you are well.

Last Saturday, 10 years into my ownership, I traded my beloved 11-year old Focus 1.6 Zetec hatch when the jacking point collapsed whilst I was investigating which sensor on the exhaust was switching on the engine warning light. Luckily it went as I was putting a 2nd jack under as it went...

Onny rode up, I bought a 53 Mondeo TDCi 130 estate with I an apparently true 70k on the clock and 6 months "gold warranty".
Fantastic bit of kit so far and It came with receipts for new clutch, exhaust, discs, pads and - surprisingly - brake calipers front and rear. Didn't mention bearings though.

The only pain so far is that it has exactly the same problem as you have - ABS cutting in under gentle check braking below about 10 mph. Hard braking at higher speeds is fine.
To me it feels like it's front driver's side but I may be wrong. When you switch on, the ABS light comes on, runs its check and goes out.

Now, please remember I'm new to this forum stuff and I may be writing piffle but reading another thread  - "ABS Long Running Problem" started by RW.Galway on the 9th Feb 2012 - there's a possibility that, when they replaced your wheel; bearings and possibly mine - they may have fitted them the wrong way round.
If I've read the replies to the thread correctly, the wheel bearings have the sensor rings built-in.
The face that should be towards the actual sensor looks "like old cassette tape" and the shiny face of the bearing should be away from the sensor.

Also, please bear in mind I'm not an expert (I designed brakes at Lucas Girling for 17 years but never ventured into ABS witchcraft) but ABS cutting in at low speeds sounds like a sensor has no idea what's going on when the car's slowing down.  Considering there's no ABS fault light when switching on - ie stationary - there can't be a problem with the sensor/wiring/connectors.
However there must be a problem when the brakes are on at low speeds leading a sensor to think that one of the wheels is locked and firing the ABS.
In my simple mind, this agrees with a sensor ring problem from the above-mentioned post: If the wheel bearings do incorporate the sensors then it's most likely the bearing's been fitted backwards.

I'll be finding out how good my "gold warranty" is in the next week or so.

[PURPLE_2L_LX]

Gold warranty probably wont cover the brakes are they are wear and tear items.

probably only covers anything that doesnt wear or break.  If you keep thinking that you wont
be dissapointed when they fail to payup.

[Dontellimpike]

Reckon you're totally on the money, Purple_2L_LX. It may turn out to be Fool's Gold.
I'll report back after I've spoken to them on Saturday.

Must say after owning it a week my TDCi 130 (6) estate seems to be a cracking bit of kit despite the ABS problem. Quiet, smooth, plenty of poke, drives well but not quite as sharp as my old Focus Zetec.

And why is the West Midlands nowhere real? Seems pretty real outside my house.

[Dontellimpike]

Hi Gurus. I hope this long waffle may help.

After my post on the 22nd Feb I finally got my ABS fixed yesterday and - to my amazement - it was done under the warranty.
Briefly to recap - I had exactly the same problem as 2mondeos who started this thread - intermittent ABS firing when it shouldn't, no warning lights.

After I posted my notes above, I popped back into the dealer & told them about the problem. Good as gold, they plugged in their diagnostics, found no recorded faults on the car's ECU and then ramped it, pulled out the rear sensors & cleaned out the area with an airline and also cleaned around the front sensors.
Unfortunately this made it worse: the ABS was now firing every time I touched the brake pedal - any speed, any time and still no warning lights.

Rang the warranty people the next day and they said I'd have to pay for diagnostics but they should cover the fix.
I then took out the 20A fuse which disabled the ABS/TC and made the dashboard light up like a Christmas tree but at least I knew when the car was going to stop.

So, last week I popped the fuse back in & went to see a local-ish expert (Road Runner, Sutton Coldfield) who had more specialist diagnostic kit. He charged me 30 quid but his equipment actually interrogated the ABS ECU and he found error code C1235 stored which is "Right Rear wheel speed sensor input signal missing" even though there were still no warning lights on the dash.
He cleared the message, took the car for a drive & read live data from the speed sensors. Pretty cool & this found that the right rear speed sensor was consistently reading lower than the other 3 sensors; At 30mph it was 8km/h (5mph) down - about 16%. Therefore the ABS believed the right rear wheel was slipping every time the brakes were applied and so fired the ABS on the other 3 wheels.

I popped back to the dealer, told them the problem and suggested they change the RR hub/sensor ring assembly under warranty. They duly did this yesterday and now I have ABS working properly again.

Why no warning lights? My best guess is this: There was no problem with the speed sensor - it was the sensor ring.
The ABS initial check is when the car's stationary and at this point the ABS ECU is talking happily to all of the speed sensors so no warning lights.
Then, as far as I've read on t'internet, the ABS runs a check when the car reaches about 6km/h. If it finds a fault at this point (e.g. wheel speed discrepancies) it puts the warning lights on. However, I would guess that But, at 6km/h (about 4mph), a 16% wheel speed difference would equal 0.6mph which it is possible is small enough to be ignored.

The only other thing of note was a comment by the chap who read the sensors who said there are some very cheap pattern hub assemblies about and the sensor rings in these are rubbish which can cause the under-reading problem. Which possibly may explain 2mondeos problem occurring after having a rear wheel bearing changed.

Hope this helps.

[PURPLE_2L_LX]

Excellent,

All we need to know now is what brand are these rubbish bearings/sensors and who supplies them?

[Horace321]

Hi people,

I've got a MK3 2005 TDCI 2.0 130ps 5 dr hatch.  I had the abs pulsing intermitently under light to moderate braking, following replacement of both front an rear bearings.  Obviously I knew something wasn't right and the ABS should not pulse under normal braking unless for some reason traction is lost.

Well, as there was no way of knowing which bearing was at fault, I lived with it for a while.  Eventually, the ABS light will come on after a short while and stay on until the engine is turned off/restarted.  Then after a short while, the brakes will pulse etc and the ABS light will come back on again.

It's worth noting, that while the ABS light is on, YOU DON'T HAVE ABS BRAKING.  Your brakes may pulse under light braking, but believe me, when you stamp on the brakes - all your wheels WILL lock up.  It's also an MOT fail.

I had a diagnostic check done on 8/1/13 - it cost me £20.  It showed up no ABS signal from the near side rear bearing.  The bearing was only 8 months old, obtained from a motor factors and had done only 8k miles.  It was a QH (Qinton Hazell QW coded item).  This isn't a cheapy ebay part - they cost about £90 after VAT.  The rear bearing is a sealed unit, bearing, hub and sensor.

The bearing was still under warranty.  So, I was entitled to a replacement, no quibble.  Out of interest, I enquired about the cost of the sensor only.  This was £23 - and keeping in mind it may not solve the signal issue anyway if the problem is hidden away inside the (sealed) bearing, I decided against even trying a replacement sensor.

Just out of interest, my offside rear bearing was changed in September - it's a Veco item, cost about £65 from the same factors, so it will be interesting to see how long this one lasts...:/

On MK3 Mondeos - there are no ABS Rings (reluctor rings).  

On the front bearings, there are magnetic rings inside the actual sealed ballraces themselves - thus the sensor side of the bearing has to go in first and furthermore is very easily damaged if pinched or incorrectly fitted.

As already described, on the rear bearings, they are sealed and come as complete bolt-on hubs, bearing and sensor.  The rear sensors are replaceable and bolt on with a small Allen headed bolt - if anyone here has had any luck changing just these rear sensors, it would be interesting to hear from you.

Horatio

[Horace321]

Dontellimpike, on 13 March 2012 - 08:01 PM, said:

Hi Gurus. I hope this long waffle may help......

So, last week I popped the fuse back in & went to see a local-ish expert (Road Runner, Sutton Coldfield) who had more specialist diagnostic kit. He charged me 30 quid but his equipment actually interrogated the ABS ECU and he found error code C1235 stored which is "Right Rear wheel speed sensor input signal missing" even though there were still no warning lights on the dash........

.....Why no warning lights? My best guess is this: There was no problem with the speed sensor - it was the sensor ring.

I have no idea why your abs light hasn't come on - mine didn't either at first, but it does now after a few months of living with it.  I think it must be a percentage error - it has to be greater than a certain preset threshold before the ECU puts the ABS light on, and in doing so, by passes the ABS system.  I know that to test the sensor with a multimeter, on a resistance setting, if you find an open circuit while turning the wheel, the sensor/ring is faulty - it should read 1000-2000ohms.

The ring and sensor both have to work, otherwise the same fault code will show: C1235 (Rear right)
or in my case C1236 (Rear left).  Either of these problems should trigger your ABS fault light and I suspect that in time, it would do.

Regards the magnetic rings inside the bearings, if these fail/break/get dirty, changing the sensor won't help - really the only safe bet - considering labour charges and general ball ache - is to just replace the bearing.  No laughing matter on the rear, because it's the whole hub, sensor, bearing.

[PURPLE_2L_LX]

If you have a laptop you can buy an F-Super off ebay for under £20. Save you paying £20+
for diagnostics next time.

It reads ABS codes also.

[Horace321]

PURPLE_2L_LX, on 12 January 2013 - 01:38 PM, said:

If you have a laptop you can buy an F-Super off ebay for under £20. Save you paying £20+
for diagnostics next time.

It reads ABS codes also.

Cheers for that, I'll definitely get me one of those!