ABS Bearing question

[Brim987]

Hi All,

Hopefully this is an easy question for the more mechanically minded... It's a general ABS question.

I keep trying to fix the ABS on the trusty (sort of) Marea, and the next thing to try is changing the bearing with the ABS bit in.
(Sensor already changed). I saw this fixed the issue on a 500 (youtube) so we'll give it a go.

My question is whether I'll get away with just the bearing kit (ABS version) or if I need the whole hub unit.
I imagine (and hope) it's just the bearing bit but thought I'd better check..

Thanks for any thoughts.

Example pics of the options..

Steve

 

[portland_bill]

That's looking rather nasty isn't it, but should clean up reasonably well. My only concern would be the drive flange splines, they need cleaning and inspecting to ensure they're still a good fit on the CV joint.

What diagnosis have you done to get you to this stage? Are you sure it is that wheel that has lost its ABS signal? A known good sensor swapped from the other side can help diagnosis, if they're not handed, but also check the wiring carefully, all the way from sensor to ECU. The reluctor ring inside the bearing should not 'fail', as it is just a ring of metal rods, and should be sitting in grease, or moulded into the seal, not really a wear item.

 

[Brim987]

That's looking rather nasty isn't it, but should clean up reasonably well. My only concern would be the drive flange splines, they need cleaning and inspecting to ensure they're still a good fit on the CV joint.

What diagnosis have you done to get you to this stage? Are you sure it is that wheel that has lost its ABS signal? A known good sensor swapped from the other side can help diagnosis, if they're not handed, but also check the wiring carefully, all the way from sensor to ECU. The reluctor ring inside the bearing should not 'fail', as it is just a ring of metal rods, and should be sitting in grease, or moulded into the seal, not really a wear item.

Thanks for the reply, I'm desperately trying to save this car for my son since his grandad had one. This ABS light is the only issue we can't seem to fix and it's an MOT failure and, therefore, a car killer.
The pictures were just examples I found, it seems there are bearing kits, hubs and then the whole unit pictured. I'm still not clear if I need the
hub and the bearing? If it's inside the bearing then I guess just an ABS version of a bearing kit would suffice?

The history is that the light came on occasionally and then stayed on. I bought some software and got a code (after 4 garages inc Fiat had failed).
The code said front passenger speed sensor. We changed the sensor to no avail.

My next step is to get a multimeter on the abs from the wheel and check there's no signal there, if there is then it might be wiring (yikes tracking that isn't in my comfort zone).
Still need to get a minute to try that multimeter test out:

()

I found this video:
,

It goes on a bit but jump to 11:50. replacing that unit fixed an identical problem on a fiat 500. I completely agree about it not being a wear item, but it fixed it in that case. It's also why my local garage have given up on it and suggest I scrap it but that would break my boy's heart.

The garage are very reluctant to do much else without getting into discs/pads/pipes etc but I don't want all that expense if we can't fix the abs.

Here's some pics that my mechanic took of our actual car.

Steve

 

[portland_bill]

Always better to have pics of the offending vehicle.
The reluctor ring area on the bearing seal looks horrid. Is that just rust from elsewhere, or is the seal itself deteriorating? If the crap on the surface is from elsewhere, a good clean up, of bearing seal, hub and CV joint may fix the problem. If the seal has deteriorated, taking the reluctor ring with it, a new bearing should sort the issue.
Spend a bit of time with wire brushes and abrasives and clean everything up, as good as you can. Then get a new bearing pressed in. That should fix the ABS issue, then you can budget and plan for the rest afterwards.

 

[Brim987]

>The reluctor ring area on the bearing seal looks horrid. Is that just rust from elsewhere, or is the seal itself deteriorating?

I don't know, the pics are all I have. The mechanic told me he cleaned it up - I hope they were before pics. (!)

So, it seems my suggestion of changing the bearing (only) is the way to go.

Many thanks! I'll keep everything crossed.

Steve

 

[Ralf S.]

That looks very similar to my Stilo. A new bearing fixed mine (it has to be an ABS version, if there are ABS and non-ABS options).

I managed to break the sensor removing it from the hub (in order to press the bearing out). You have to ease it out without bending it.. it looks like just a plastic blade presumably containing some solid state.

But a new sensor wasn’t too bad.. about £15 from memory and it was pretty simple to fit.


Ralf S.

 

[Brim987]

Just an update...
I went down the garage to book in the marea for a new bearing but the mechanic told me it wouldn't be possible to do without new discs and pads (500 quid, he'll only use fiat parts).
Apparently, the discs are corroded and he thinks they'll be damaged getting them off and won't refit.
Obviously, I don't want to spend 500+ quid without knowing the ABS can be fixed first.
He previously supplied the two marea ABS pics above showing the bearing, would they have been possible with the discs on?
Do the discs have to come off to fit a bearing?
I've found a pair of new EBC discs for 40 quid (a lot better than 500!), so maybe I can find a trustworthy mobile mechanic to do the job using my supplied parts at a fraction of the cost.

Any thoughts/comments appreciated!

Cheers
Steve

 

[Pugglt Auld Jock]

Just an update...
I went down the garage to book in the marea for a new bearing but the mechanic told me it wouldn't be possible to do without new discs and pads (500 quid, he'll only use fiat parts).
Apparently, the discs are corroded and he thinks they'll be damaged getting them off and won't refit.
Obviously, I don't want to spend 500+ quid without knowing the ABS can be fixed first.
He previously supplied the two marea ABS pics above showing the bearing, would they have been possible with the discs on?
Do the discs have to come off to fit a bearing?
I've found a pair of new EBC discs for 40 quid (a lot better than 500!), so maybe I can find a trustworthy mobile mechanic to do the job using my supplied parts at a fraction of the cost.

Any thoughts/comments appreciated!

Cheers
Steve

Something like this just leaves me itching to plug in MES and graph what the ecu thinks it's seeing from that sensor. However, in the absence of that - you want to check out the wiring before spending big money on the other items. You say a new sensor has been fitted - I hope the plug connections were carefully checked and I would include the connection to the ABS ECU at the other end - It's easy, just a plug to pull, visually inspect - including the wires where they enter the plugs as corrosion can establish where the wire is crimped to the back side of the connector if the seal gets damaged - possibly by back probing etc. If you can identify the wires, maybe from their colour codes? check for continuity from the ECU plug to your wheel sensor (wire colours should be identifiable at either end) Probably the most common thing is corrosion at the wheel end plug, but the wire may be broken inside the insulation where the wire transitions between suspension arm and chassis fixings due to flexing. ECUs do go wrong but not often so I always leave that as the last "suspect" in the train of investigation unless I get a fault code that specifically points to it.

On the bearing side of things this may help:



I know it's a Punto, but the Marea - I'd guess? - is going to be similar?

All looks oh so easy in this video but on older well rusted hubs, like yours, that big circlip which retains the bearing in place, can be an absolute sod to shift. A few years ago I did a front wheel bearing on my boy's car, because it was "noisy" which was a very similar setup to yours. Knowing that shifting the bearing would be difficult my local garage, where I'm well known and friends with, said if I stripped the hub out of the car and brought just the hub in on it's own - so it looked like the picture you've posted of your hub - they would remove the old bearing and fit the new one for me. In the event I was allowed to stay and watch and it was very interesting. The circlip had completely rusted into it's groove and took a couple of hours to chip out in wee pieces. The chap doing the job had a wonderful selection of chisels and "pointy" tools, many looked custom made, which he used to do this. But then we had the drama of pressing the bearing out of the hub. At first it just wouldn't move even though many tons of pressure were applied on their big floor standing hydraulic press. He then soaked the whole thing in more releasing oil and scraped away with more "pointy" tools around where the edge of the bearing was located in the bore of the hub. Then it was back onto the press again and with great pressure applied there was a sudden loud CRACK and the bearing started to move. After that it came out the rest of the way quite easily and, after a good clean up of the bore with some abrasive tape, the new bearing went in nice and smoothly. Started around 09.30 in the morning. I had a cup of tea with them for my lunch and left for home around 14.00 hrs. (I was chatting to "the boss" after the fitter had finished though and I do like to chat.) I couldn't believe it when they only charged me £40 all in - but they know they are my first stop for heavy stuff I can no longer manage, like clutches etc. By the way, I've never seen a drive flange driven out of a bearing simply with a hammer like he does. It's very usual for them to be so tight that the inner race of the bearing stays on the flange and then you've all the extra "fun" of pulling the race from the flange before you can reuse it!. (think angle grinder and chisel!)

I must say I'm a bit disturbed by your chap's insistence on manufacturer parts only. I would say that all, without exception, of the small garages around me would fit OE quality pattern parts obtained from one of the local factors. I know the Honda chap and the VAG guys prefer to fit genuine manufacturer's parts on cars up to 5 years old, then they go to OE pattern parts from the factors after that to cut repair costs to customers on older cars.

I really can't see that the discs and pads interfere in any way with doing the wheel bearing, although it's entirely possible that they may be in such poor condition as to be unserviceable for further use and this may be what they are meaning. Still no need to use expensive dealer parts though. Oh and yes, to get those pictures of the hub, the disc and driveshaft would have been removed - see the video.

PB suggests above that the drive shaft and hub splines are carefully checked and I'd agree. However, enlarging your image, I doubt if they are a problem and should clean up nice enough. The hub, of course, has to be pressed out of the middle of the old bearing and pressed back into the middle of the new one. It should be checked for wear and damage to it's outer diameter where it fits back into the new bearing as it's important it's a good tight fit.

Frankly, as long as there isn't an ECU problem here, this shouldn't be a humongous problem to solve for an experienced and competent engineer. Good luck with it all. Please do keep us informed, I'll be following your progress with interest.

 

[Brim987]

Something like this just leaves me itching to plug in MES and graph what the ecu thinks it's seeing from that sensor. However, in the absence of that - you want to check out the wiring before spending big money on the other items. You say a new sensor has been fitted - I hope the plug connections were carefully checked and I would include the connection to the ABS ECU at the other end - It's easy, just a plug to pull, visually inspect - including the wires where they enter the plugs as corrosion can establish where the wire is crimped to the back side of the connector if the seal gets damaged - possibly by back probing etc. If you can identify the wires, maybe from their colour codes? check for continuity from the ECU plug to your wheel sensor (wire colours should be identifiable at either end) Probably the most common thing is corrosion at the wheel end plug, but the wire may be broken inside the insulation where the wire transitions between suspension arm and chassis fixings due to flexing. ECUs do go wrong but not often so I always leave that as the last "suspect" in the train of investigation unless I get a fault code that specifically points to it.

On the bearing side of things this may help:



I know it's a Punto, but the Marea - I'd guess? - is going to be similar?

All looks oh so easy in this video but on older well rusted hubs, like yours, that big circlip which retains the bearing in place, can be an absolute sod to shift. A few years ago I did a front wheel bearing on my boy's car, because it was "noisy" which was a very similar setup to yours. Knowing that shifting the bearing would be difficult my local garage, where I'm well known and friends with, said if I stripped the hub out of the car and brought just the hub in on it's own - so it looked like the picture you've posted of your hub - they would remove the old bearing and fit the new one for me. In the event I was allowed to stay and watch and it was very interesting. The circlip had completely rusted into it's groove and took a couple of hours to chip out in wee pieces. The chap doing the job had a wonderful selection of chisels and "pointy" tools, many looked custom made, which he used to do this. But then we had the drama of pressing the bearing out of the hub. At first it just wouldn't move even though many tons of pressure were applied on their big floor standing hydraulic press. He then soaked the whole thing in more releasing oil and scraped away with more "pointy" tools around where the edge of the bearing was located in the bore of the hub. Then it was back onto the press again and with great pressure applied there was a sudden loud CRACK and the bearing started to move. After that it came out the rest of the way quite easily and, after a good clean up of the bore with some abrasive tape, the new bearing went in nice and smoothly. Started around 09.30 in the morning. I had a cup of tea with them for my lunch and left for home around 14.00 hrs. (I was chatting to "the boss" after the fitter had finished though and I do like to chat.) I couldn't believe it when they only charged me £40 all in - but they know they are my first stop for heavy stuff I can no longer manage, like clutches etc. By the way, I've never seen a drive flange driven out of a bearing simply with a hammer like he does. It's very usual for them to be so tight that the inner race of the bearing stays on the flange and then you've all the extra "fun" of pulling the race from the flange before you can reuse it!. (think angle grinder and chisel!)

I must say I'm a bit disturbed by your chap's insistence on manufacturer parts only. I would say that all, without exception, of the small garages around me would fit OE quality pattern parts obtained from one of the local factors. I know the Honda chap and the VAG guys prefer to fit genuine manufacturer's parts on cars up to 5 years old, then they go to OE pattern parts from the factors after that to cut repair costs to customers on older cars.

I really can't see that the discs and pads interfere in any way with doing the wheel bearing, although it's entirely possible that they may be in such poor condition as to be unserviceable for further use and this may be what they are meaning. Still no need to use expensive dealer parts though. Oh and yes, to get those pictures of the hub, the disc and driveshaft would have been removed - see the video.

PB suggests above that the drive shaft and hub splines are carefully checked and I'd agree. However, enlarging your image, I doubt if they are a problem and should clean up nice enough. The hub, of course, has to be pressed out of the middle of the old bearing and pressed back into the middle of the new one. It should be checked for wear and damage to it's outer diameter where it fits back into the new bearing as it's important it's a good tight fit.

Frankly, as long as there isn't an ECU problem here, this shouldn't be a humongous problem to solve for an experienced and competent engineer. Good luck with it all. Please do keep us informed, I'll be following your progress with interest.

Firstly, wow. Thank you for taking the trouble to put that reply together.
I should say I'm happy to get the discs/brake pipes/welding/suspension/cambelt/respray etc! done - if the ABS can be sorted...
I'm just on a mission to save it.
re: graph what the ecu thinks it's seeing from that sensor
Interesting, one of the mechanic's objections was that there was no way to get live data and as I type I've just seen F5 - Graph on my picture.
Doh, really? - I was just so utterly stunned to finally get a code that I hadn't noticed that. I'll recheck and see if that shows anything tomorrow.
That said, I'm not sure how to interpret it... More research...

Here's what I manged to get from the diagnostic software (which was another fight with windows 10 port latency speeds and who knows what solved by these wonderful forums).

I intend to put a multimeter on the abs sensors of both front wheels, the passenger is reported faulty so if I get no signal off that and the other side does have a signal then that's a big pointer to the problem being the bearing. (given that the sensor has been changed already).
There might also be a wiring problem later of course, let's hope not.

RE: check for continuity from the ECU plug - now that's where I get lost, I don't know where that is, I'll have to read up some more.

I'm guessing the mechanic is saying he doesn't expect the disc to go back on after the bearing change. Still seems odd if it's been off once to examine it all. Hmmm. I know he thinks it's madness to spend money on it, he's probably right but it's a sentimental thing to keep my young son happy. It only needs to go back on for a 30 second drive to test if the light goes out.... I don't even care if there's no front brakes in the car park...

I'm having real trouble finding a local mobile mechanic without awful reviews (running off with ignition key etc!)
Perhaps I'll ring round some garages to see if I can find one that will fit parts supplied by me or at least not fiat.
(See my other post about an injector being nearly 400 quid.)

Thanks again, I'll post an update when I have one.
I'll fix this or die trying..

 

[Pugglt Auld Jock]

Oh yes, I know all about "emotional attachment" to cars. We tend to keep all our cars (been 6 in the family for many years) and although I'm a little less proactive, because of the limitations of my aging body, I still do most of the service and repair work on them. We tend to buy a car at 18 months to 2 years old and then keep them until they are beyond economic repair. We had both our Panda Parade and Seat Cordoba Vario (estate) for over 20 years each, both cars were deeply loved and still I miss them. Currently the Astra is a 2007 plate, Jazz is a 2008, Panda is a 2010, Punto is a 2012 and my "new" Ibiza is 2016 with my older boy having a Kia Rio bought new in 2017 and still under extended warranty so I hardly ever touch it. In select male company I have been known to, rather crassly, claim to know all the "nooks and crannies" on my cars better than the nooks and crannies on my long suffering wife!

Graphing is easy. In this case, jack up the wheel so you can spin it. Plug in the reader and turn on the ignition. Go to "parameters" and click on the sensor for that wheel, then click on graph. Spin the wheel and you should see a waveform generated on the screen. I've not done a Marea but I'd guess it's going to be a sine wave form - I think some late model vehicles produce a square (digital on/off type trace? but I've not seen that myself) This may help: https://apecautomotive.co.uk/techmate-guides/abs-sensors/. Is that the free version of MES you're showing in your post? If so the free version offers very limited functionality so you may or may not be able to use it to graph that sensor output. If you're going to do any more FIAT "stuff" in the future I can thoroughly recommend buying a fully licensed version for yourself - By the way, I had the same initialization/computer problems when setting up my licensed copy. I'm not deeply into computers and found it very frustrating but, like you, I got lots of help from folk on here and, in particular, Grant at Gendan https://www.gendan.co.uk/ who, to this day, continues to engage with me about all things Fiat and VAG related. - Very helpful and knowledgeable people who are well worth a phone call if you are thinking of buying.

Discs can, in extreme cases, rust onto the drive flange so securely that they have to be destroyed to remove them. If rusted on so badly that they can't be removed with just a firm tap with a "persuader" DON'T BEAT THE BEJESUS OUT OF THEM WITH A HUMONGOUS HAMMER. you're quite likely to cause damage to the wheel bearings doing this. Instead use an angle grinder to grind slots in the old disc then use a shallow tapered chisel to open out the slots. The disc material is quite brittle and will quickly crack due to the stress concentration caused by the slots you've ground with the angle grinder allowing it to spread slightly and then you can remove it.

Roughly whereabouts in the country are you? Assuming you are in the UK there may be a forum member in your general area who could recommend a good mechanic/garage or even offer some help themselves?

 

[Brim987]

Oh yes, I know all about "emotional attachment" to cars. We tend to keep all our cars (been 6 in the family for many years) and although I'm a little less proactive, because of the limitations of my aging body, I still do most of the service and repair work on them. We tend to buy a car at 18 months to 2 years old and then keep them until they are beyond economic repair. We had both our Panda Parade and Seat Cordoba Vario (estate) for over 20 years each, both cars were deeply loved and still I miss them. Currently the Astra is a 2007 plate, Jazz is a 2008, Panda is a 2010, Punto is a 2012 and my "new" Ibiza is 2016 with my older boy having a Kia Rio bought new in 2017 and still under extended warranty so I hardly ever touch it. In select male company I have been known to, rather crassly, claim to know all the "nooks and crannies" on my cars better than the nooks and crannies on my long suffering wife!

Graphing is easy. In this case, jack up the wheel so you can spin it. Plug in the reader and turn on the ignition. Go to "parameters" and click on the sensor for that wheel, then click on graph. Spin the wheel and you should see a waveform generated on the screen. I've not done a Marea but I'd guess it's going to be a sine wave form - I think some late model vehicles produce a square (digital on/off type trace? but I've not seen that myself) This may help: https://apecautomotive.co.uk/techmate-guides/abs-sensors/. Is that the free version of MES you're showing in your post? If so the free version offers very limited functionality so you may or may not be able to use it to graph that sensor output. If you're going to do any more FIAT "stuff" in the future I can thoroughly recommend buying a fully licensed version for yourself - By the way, I had the same initialization/computer problems when setting up my licensed copy. I'm not deeply into computers and found it very frustrating but, like you, I got lots of help from folk on here and, in particular, Grant at Gendan https://www.gendan.co.uk/ who, to this day, continues to engage with me about all things Fiat and VAG related. - Very helpful and knowledgeable people who are well worth a phone call if you are thinking of buying.

Discs can, in extreme cases, rust onto the drive flange so securely that they have to be destroyed to remove them. If rusted on so badly that they can't be removed with just a firm tap with a "persuader" DON'T BEAT THE BEJESUS OUT OF THEM WITH A HUMONGOUS HAMMER. you're quite likely to cause damage to the wheel bearings doing this. Instead use an angle grinder to grind slots in the old disc then use a shallow tapered chisel to open out the slots. The disc material is quite brittle and will quickly crack due to the stress concentration caused by the slots you've ground with the angle grinder allowing it to spread slightly and then you can remove it.

Roughly whereabouts in the country are you? Assuming you are in the UK there may be a forum member in your general area who could recommend a good mechanic/garage or even offer some help themselves?

Ok, thanks for that info, much appreciated - I'm hoping to have a play tomorrow.
I'm near Northampton J15 M1, I did try a post a while ago asking for a garage that could diagnose the ABS but no joy.
However, I'm a bit more confident on the diagnosis now, just need somebody to fit the bits.
Given that the disc came off to get the pics, I'm hopeful that won't be too painful.(on one side anyway...)

Two nights running I've been dreaming about marea abs systems, dreams used to be so much more interesting (nooks and crannies mainly).
Ho hum.

Steve

 

[Pugglt Auld Jock]

Two nights running I've been dreaming about marea abs systems, dreams used to be so much more interesting (nooks and crannies mainly).
Ho hum.

Steve

Safer dreaming about ABS. Rumour has it the other causes blindness!

 

[ernibv]

Hi All,

Hopefully this is an easy question for the more mechanically minded... It's a general ABS question.

I keep trying to fix the ABS on the trusty (sort of) Marea, and the next thing to try is changing the bearing with the ABS bit in.
(Sensor already changed). I saw this fixed the issue on a 500 (youtube) so we'll give it a go.

My question is whether I'll get away with just the bearing kit (ABS version) or if I need the whole hub unit.
I imagine (and hope) it's just the bearing bit but thought I'd better check..

Thanks for any thoughts.

Example pics of the options..

Steve

Hi Steve,
Your question has led to a very interesting and technical discussion.
What I don't see is ( to my mind ) the most simple question: Does the ABS work ?
This should make a diagnosis easier.
Test: When ABS is working properly, the driver may feel the brake pedal suddenly drop, followed by a rapid pulsing sensation. There may be a grinding or buzzing noise coming from the vehicle during the period ABS is activated. It may also feel like the brake pedal is pushing back when ABS activates.

I will be doing my rear wheel bearings Sunday ( after church, of course ). I have the RIDEX 654W0451 set with ABS. Since we will be doing the complete trailing arm, this will all be an interesting challenge.

grtz
Eric

 

[Brim987]

Hi Steve,
Your question has led to a very interesting and technical discussion.
What I don't see is ( to my mind ) the most simple question: Does the ABS work ?
This should make a diagnosis easier.
Test: When ABS is working properly, the driver may feel the brake pedal suddenly drop, followed by a rapid pulsing sensation. There may be a grinding or buzzing noise coming from the vehicle during the period ABS is activated. It may also feel like the brake pedal is pushing back when ABS activates.

I will be doing my rear wheel bearings Sunday ( after church, of course ). I have the RIDEX 654W0451 set with ABS. Since we will be doing the complete trailing arm, this will all be an interesting challenge.

grtz
Eric

After starting, the brakes are horrible (pulsing, very little actual braking) until the ABS light comes on (30 seconds maybe) then the ABS is off and all is well.
(Yes, there's whine for a while during that 30 seconds , which I guessed was the ABS pump.)
It amuses my son no end that the brakes don't work until the light comes on saying the brakes don't work.

Unfortunately, I didn't get to do any planned tests today, life got in the way..
more as it 'appens.

 

[Brim987]

Ok, here's the news.... I don't know if it's good or bad.

The original plan was to put a multimeter on the connection point of the left front abs and if there's no signal then it's probably the bearing...
but I couldn't see a connection junction and the wire disappeared inside to where I couldn't follow it, so I gave up on that and tried to get some real time graph info.
As you'll see from the pics, I got a signal from both sides by just hand cranking the hub, they look a little different but that could just be me being inconsistent in rotating it. Anyhow, there's a signal which I really wasn't expecting, is it a bad signal in some way? - I've no idea.
I think to get a true comparison I'd have to rig something up to let me get a graph as I drive up the road. (a 5m USB cable extension through the window...)
All thoughts appreciated at this point. I am leaning towards it just being cursed.

(As an aside, the car had alloys on when I bought it and one side seems to have a spacer missing, any idea how hard that will be to source?
Not that it matters anyway unless the ABS can be sorted....)

 

[ernibv]

There are 2 physical tests for the ABS sensor: resistance and millivolts AC.
If there is no resistance or erratic resistance, the sensor is bad or dirty.
If there is resistance between 1 and 8k ohms, but no volts AC with hand rotation, the sensor is bad (and probably not just dirty).

 

[Pugglt Auld Jock]

'evening Steve. The first observation to make is that those discs are truly 'orrible! She's going to feel like a Rolls Royce with new ones fitted - pads too of course. Are you a Copa slip man or have you embraced the new ceramic brake grease revolution?

As to the sensor graphs. The first graph, for the left front, makes some sort of sense if you spun it up twice with a pause in between where it straight lines? The output for the front right looks pretty weird with it's "glitchy" waveform - were you spinning the wheel smoothly, i.e. not speeding up and slowing down? and yet it's the left front that is flagged up as faulty, not the right front? Need to know where and how you are connecting in to take those readings, presumably at the OBD port but what interface do you have? Some of the cheapie ones of the likes of eBay are notorious for either failing to connect properly or causing all sorts of problems.

To take this sort of reading I'd be connecting up to the OBD socket and recording the sensor output whist driving - or, if I couldn't drive the car I'd stick the front end up in the air and, with each wheel blocked in turn, record the output on either side with the car in gear and engine running. That way each wheel would be turning at the same speed when checked so the outputs should be equal. If you do try this then handbrake on tightly and static wheels chocked please. (and if you have a more "exotic" car with a limited slip diff then bear in mind both driven wheels will want to turn together so she'll try to drag herself off the axle stands) Trying to spin front wheels by hand is unlikely to give comparable outputs due to the drag of the transmission and inability to maintain a consistent rotational speed.

Has anyone yet mentioned that we are forgetting one of the most basic and simple "must do first" tasks on an older car like this - which is, to pull all relevant plugs and connectors, check for internal corrosion and mechanical damage, spray with contact cleaner, work in and out/together and apart several times to remake connections and then recheck to see if the original problem has "magically" disappeared! The electric current in electronic systems is very low and easily defeated by a slightly high resistance in a connection.

I'm definitely not an electronics engineer, much happier hitting things with hammers and levering with my biggest screwdriver! But I'm following this thread with great interest so please do keep on posting. Can't wait to see the outcome!

 

[g8rpi]

The fact that MES is seeing a signal form the sensors is good news. At least the ECU is seeing a signal. It is most likely a reluctor fault. The reluctor is in the bearing. You can get a new bearing for about £15 . The biggist issue is getting the old one out unless you have the right tools.
The disks and pads do need replacing but use good aftermarket parts, not Fiat. The garage who want's to fit only Fiat parts is just making more profit. You should be able to take the disk off yourself. Remove the caliper and the wheel locating pin and it should come off. What are your mechanical skills and tool availability? you could take the upright complete wirh bearing off yourself and then get a garage (one working with old cars or maybe landrovers would be good) to change the bearing. I'd be tempted to do both sides. The parts should be about £150-£200 for both sides.
Roughly where are you located, somone may be able to suggest a garage.
Not many Mareas left on the road, it would be nice to keep one going. I had one several years ago.

Robert

 

[varesecrazy]

As a thought..

Spin the wheel you suspect has a problem.. check the MES is talking about the same wheel ;-)

You dont want to change the wrong bearing :-(

 

[Brim987]

REull all relevant plugs and connectors,

I get lost at this point, I couldn't even trace the wheel sensor connector.
Any pointers appreciated, I am a long way from a mechanic I'm afraid. Literally and figuratively. ;-)

Many Thanks to all that replied, I do appreciate it but it's now 1.30 in the morning. (I'll have a better read through tomorrow).

If I can find a usb extension I might try getting a driving along reading mainly out of interest, the ones posted were just me hand cranking it.

At this point I think I'm going to find a garage using OEM parts and just do the bearing (yes both sides) and discs as a hail Mary (as the Americans say).

If it doesn't work then, well at least it will go to Fiat heaven with some shiny bits.
(and my son will weep for months...he adores this car)

Steve
P.S quick replies since I've woken up again now:
yes MES is talking about the same wheel.

re: Are you a Copa slip man or have you embraced the new ceramic brake grease revolution?
I don't even understand the question...

interface is a vag kkl with 3 pin convertor, seems reliable now I have the com port speeds sorted out

More as it happens, might be a short while before i can get the work booked in...