Technical ABS light coming on after having work done

[Tessia]

Hi again,
2008 1.2 sport

I brought the car in to a garage to have varies bits of work done, before this I never had the ABS light come on. Drive away from the garage and the ABS light came on.

Now, when I turn the ignition on and the dashboard lights settle down, the ABS light does not stay on, it turns off. Start the engine, still off. Pull off and it seems that as soon as I hit around 30mph, the ABS light comes on and stays on for the remainder of the journey. When I turn the car off and back on, ABS light goes off, rinse and repeat.

One of the jobs that was done at the garage was a handbrake cable replacement. After a bit of research, I'm guessing that while they were doing this, some dirt/rust has got onto the ABS sensor and is causing the issue? Does this sound about right? If so, where can I locate the sensor? If not, what would be the next guess?

If it's an easy fix that won't cost anything, such as cleaning the sensor, I'll do it myself. If it's not, I'll go back to the garage as this was never an issue prior to them working on it.

 

[John202020]

On a new car very simple to replace 5 mins, on an old car a total nightmare and quite expensive £150

Rear ABS Sensor 52199224

www.shop4parts.co.uk

Found a cheaper one £58

Pagid ABS / Traction Control Sensor | Euro Car Parts

Pagid ABS / Traction Control Sensor at the lowest UK prices from Euro Car Parts UK’s No.1 for Car Accessories, Car Styling & Car Care. Buy today Online, In store or by Phone + Branches Nationwide – Next Day UK Free Delivery.

www.eurocarparts.com

 

[Tessia]

On a new car very simple to replace 5 mins, on an old car a total nightmare and quite expensive

Rear ABS Sensor 52199224

www.shop4parts.co.uk

£120 for a sensor?! Well ****! I'll definitely be going to the garage if that is the solution as it was never a problem before they worked on it.

Is it worth trying to clean the ones that are on there first? I've read that dirt getting onto them can cause similar issues, however, when I read about that, the car in question would have the ABS light come on and off multiple times in one journey, whereas on mine, once it's on, it stays on.

Edit: £58 is better but still, if they damaged it, they can sort it.

 

[jackwhoo]

Hi,
From your description I think you may be on to something with your thoughts that sensor is dirty.
If there was an electrical fault with sensor/system the and light would not go out.
Fact that and light goes out initially but comes on again after car is moving leads me to think that and module is "seeing" one wheel speed very much different to the other 3 wheels.

Looking at the sensor sensing end requires removing the brake drum on one side at a time. Do it yourself if you can and wish to.

I suggest speaking politely to the garage and asking them to check what they have done.

Please let us know how you get on.

Cheers
Jack

 

[John202020]

It's possible the sensor or stator ring has got dirty, if you know what you're doing there's no reason not to give it a clean, you need to remove the hub, you will also be able to see if there's any physical damage to sensor or cable, if both sides changed you'll need to look at both as it could be either side?
Your issue could be proving the light was off before coming in?
£120, plus vat plus carriage

 

[steveras57]

Hi once again!
Dirt or debris seams the most likely, but you will have to check both sides of course! the slightest particle between the sensor and reluctor ring can cause a false reading and upset the system as Jackwoo said causing the light as the system thinks one wheel is turning at a different rate than expected!.
If your going in yourself i would also check the condition of the ring on each hub as the slightest of cracks can cause the same issue! i think the rings are available on e-bay etc, but can be a bit awkward to fit to the hub( sometimes need heating up to expand them enough to fit over the hub!)
Getting the hub off can also be "fun" what with the dirt/rust etc not sure if you need special tools but good sockets and maybe a half decent puller should see it give in!
good luck!
to be honest id go back to the garage first before committing to this much work!

 

[Tessia]

Hi,
From your description I think you may be on to something with your thoughts that sensor is dirty.
If there was an electrical fault with sensor/system the and light would not go out.
Fact that and light goes out initially but comes on again after car is moving leads me to think that and module is "seeing" one wheel speed very much different to the other 3 wheels.

Looking at the sensor sensing end requires removing the brake drum on one side at a time. Do it yourself if you can and wish to.

I suggest speaking politely to the garage and asking them to check what they have done.

Please let us know how you get on.

Cheers
Jack

Hi,

Thanks for the reply. I normally get notifications when I get replies from this site but didn't one this thread for some reason, hence the delay.

I'll probably try cleaning it first then if this seems a likely culprit but if that doesn't sort the issue then I'll speak nicely to the garage.

 

[Tessia]

It's possible the sensor or stator ring has got dirty, if you know what you're doing there's no reason not to give it a clean, you need to remove the hub, you will also be able to see if there's any physical damage to sensor or cable, if both sides changed you'll need to look at both as it could be either side?
Your issue could be proving the light was off before coming in?
£120, plus vat plus carriage

Hi,

Thanks for the reply. I normally get notifications when I get replies from this site but didn't one this thread for some reason, hence the delay.

It was just the one side that was done so I'll start there and see if it that fixes the issue. I agree it could be hard to prove it wasn't on prior to them doing work which is why I'll try the easy option first of looking at it myself.

 

[Tessia]

Hi once again!
Dirt or debris seams the most likely, but you will have to check both sides of course! the slightest particle between the sensor and reluctor ring can cause a false reading and upset the system as Jackwoo said causing the light as the system thinks one wheel is turning at a different rate than expected!.
If your going in yourself i would also check the condition of the ring on each hub as the slightest of cracks can cause the same issue! i think the rings are available on e-bay etc, but can be a bit awkward to fit to the hub( sometimes need heating up to expand them enough to fit over the hub!)
Getting the hub off can also be "fun" what with the dirt/rust etc not sure if you need special tools but good sockets and maybe a half decent puller should see it give in!
good luck!
to be honest id go back to the garage first before committing to this much work!

Hi,

Thanks for the reply. I normally get notifications when I get replies from this site but didn't one this thread for some reason, hence the delay.

I was hoping that as they had the drum off recently that it would be easy to get off again now. However you could be right, it be worth speaking to them first. If they are nice and offer to take a look then I'll bring it in. However if they get funny about proving that this issue wasn't there before then I will look at it myself first.

 

[steveras57]

Hi,

Thanks for the reply. I normally get notifications when I get replies from this site but didn't one this thread for some reason, hence the delay.

I was hoping that as they had the drum off recently that it would be easy to get off again now. However you could be right, it be worth speaking to them first. If they are nice and offer to take a look then I'll bring it in. However if they get funny about proving that this issue wasn't there before then I will look at it myself first.

good stuff break out the rubber gloves and wd 40 eh! let us know the progress/outcomes hope you dont find any "horrors "in there i am sure the drum will come of easy enough, its the hub if you have to remove it that might cause a bit of "bother!" lets hope not!

 

[Tessia]

good stuff break out the rubber gloves and wd 40 eh! let us know the progress/outcomes hope you dont find any "horrors "in there i am sure the drum will come of easy enough, its the hub if you have to remove it that might cause a bit of "bother!" lets hope not!

It might be a few weeks until I get around to it, British weather being what it is

Oh just a little update too, I think you were on the thread I made about the car jerking a lot when taking my foot off the accelerator. We seemed to all come to the conclusion that it was the rear dogbone engine mount.

I had that mount changed as part of the work that was done which I mentioned in this post. They had to change the exhaust centre pipe too because the flexi pipe was very badly rusted and had to be removed to get the bolts out of the mount.

Anyway, I'm glad to say that was the issue!! It still kicks a bit when taking my foot off the accelerator but not half as much and the big difference is, when it happens now, it bounces back and forth a couple times and then stops. Before having the mount changed, once the jerking started, it would keep bouncing, getting progressively worse until I put my foot on the clutch. It also feels more bouncy now whereas before it felt more clunky and you could here a metallic clanking.

Should I update my original post to mention this incase of anyone having the issue? I never know if necroing posts is allowed on various forums.

 

[jackwhoo]

It might be a few weeks until I get around to it, British weather being what it is

Oh just a little update too, I think you were on the thread I made about the car jerking a lot when taking my foot off the accelerator. We seemed to all come to the conclusion that it was the rear dogbone engine mount.

I had that mount changed as part of the work that was done which I mentioned in this post. They had to change the exhaust centre pipe too because the flexi pipe was very badly rusted and had to be removed to get the bolts out of the mount.

Anyway, I'm glad to say that was the issue!! It still kicks a bit when taking my foot off the accelerator but not half as much and the big difference is, when it happens now, it bounces back and forth a couple times and then stops. Before having the mount changed, once the jerking started, it would keep bouncing, getting progressively worse until I put my foot on the clutch. It also feels more bouncy now whereas before it felt more clunky and you could here a metallic clanking.

Should I update my original post to mention this incase of anyone having the issue? I never know if necroing posts is allowed on various forums.

Yes please update your original post with resolution-it may help someone

 

[steveras57]

It might be a few weeks until I get around to it, British weather being what it is

Oh just a little update too, I think you were on the thread I made about the car jerking a lot when taking my foot off the accelerator. We seemed to all come to the conclusion that it was the rear dogbone engine mount.

I had that mount changed as part of the work that was done which I mentioned in this post. They had to change the exhaust centre pipe too because the flexi pipe was very badly rusted and had to be removed to get the bolts out of the mount.

Anyway, I'm glad to say that was the issue!! It still kicks a bit when taking my foot off the accelerator but not half as much and the big difference is, when it happens now, it bounces back and forth a couple times and then stops. Before having the mount changed, once the jerking started, it would keep bouncing, getting progressively worse until I put my foot on the clutch. It also feels more bouncy now whereas before it felt more clunky and you could here a metallic clanking.

Should I update my original post to mention this incase of anyone having the issue? I never know if necroing posts is allowed on various forums.

woo -hoo thats another job off the list!

 

[Ralf S.]

I'm not sure this is anything to do with dirt on the sensor. The ABS sensor in the 500 is an inductive sensor, which is essentially a magnet with a coil wrapped round it. It's not normally "powered".. but (via Hall Effect?) a small current is generated whenever a magnetic object (i.e. the teeth on the ABS ring or the hub) passes the sensor.

The ABS ECU examines the current frequency from each sensor to work out whether it's normal and all wheels are the same. If you're braking and a wheel is locking up or locked up.. the ABS would reduce braking pressure on that wheel until it started rotated at the same speed as the others. If you're not braking, and it spots an anomaly in the signals (e.g. one wheel's signal is different to the others) then you get the ABS fault light.

The ABS unit only starts to monitors wheel rotation signals from 50km/h (31mph) which is why you don't see the ABS light at low speeds.. although ABS does work below this speed. Unless the ABS light is on, in which case ABS is disabled.

So.. only a lump or magnetic debris in the hub ring/teeth is going to cause a "dirt" related error. It's far more likely that the garage had to remove the sensor and did that by pulling the cable (the one used to send the ABS unit a miniscule signal) or they levered it with a screwdriver and damaged the coil (the small plastic blade at the end of the cable). I doubt that they removed the cable from the car.. but if they did, but then didn't reconnect it properly, then that would be the best/cheapest outcome.

But ABS cables are quite fragile and mechanics are generally Neanderthals.. so my money is on "they broke it".


Ralf S.

 

[jrkitching]

I was hoping that as they had the drum off recently that it would be easy to get off again now

OEM drums can be removed quite easily.

The holes the locating pins pass through are threaded. Just use a couple of suitably sized bolts inserted into the holes and tighten them evenly to pull off the drum.

Other marques of cars which don't have locating pins often have similar holes just for this very purpose, so this is a generically useful thing to know.

Not all aftermarket drums have threaded holes, but many do. If you're fitting new aftermarket drums, I'd suggest you check this before fitting. If the holes aren't threaded, run a tap through them; it'll make it so much easier to get them off again next time.

Without these threads, drums can indeed be a pain to remove.

 

[jackwhoo]

When key first on the abs system checks the resistance of each sensor circuit, if any sensor circuit is faulty the abs light will illuminate.
My opinion is as the abs light only comes on when vehicle moving one of the sensors is not reading speed similar to the other 3 sensors. Possibly caused by magnetic dirt on magnetic hub ring or sensor or damage to magnetic hub ring or sensor.

Anyway round it needs looking at .

Hall effect sensors require a power supply and so most commonly have 3 wires not applicable to the car in question.

 

[yann]

Might be best to ask garage to plug in & see where the fault is....i would be nice at first, it's possible the clipped' the sensor with the new cable.
yann.