W204 200CDI ESP/ABS inoperative

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sceh

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w123 240TD
My apologies if this post exists already but I don't seem to be able to find a clear answer.
iCarsoft found no wheel speed from the rear drivers side so I duly changed the Speed sensor and have the same result.
What next though? Is it possible the reluctor ring is at fault? Seems pretty unlikely since it is just a piece of metal.
Any ideas please? The car is diesel and has done 50K miles 2011 auto box
Thanks
 
My apologies if this post exists already but I don't seem to be able to find a clear answer.
iCarsoft found no wheel speed from the rear drivers side so I duly changed the Speed sensor and have the same result.
What next though? Is it possible the reluctor ring is at fault? Seems pretty unlikely since it is just a piece of metal.
Any ideas please? The car is diesel and has done 50K miles 2011 auto box
Thanks
The reluctor rings rust, could well be the problem.
 
Is there a definitive way to find out if it is the impulse ring or something else? The mercedes EPC and WIS is curiously silent about this and the rear ABS sensor too. Odd
 
Another possible pointer is that when this first appeared a couple of weeks ago I drove the car for 100 yards and it cleared. I don't use the car a lot and it is now back showing the errors
 
and yet another oddity..iCarsoft V2 detects no faults codes even though the warning lights are on and I would expect them to be on because of fault codes though I could be mistaken
 
Put the faulty sensor on the rear passenger side and see if it works ok, if it does then it’s your reluctor ring.
Unless it’s a magnetic bearing as mine was and not a reluctor ring.
 
The sensor is new but I shall try anyway - ta
 
My old W204 had a problem similar to this, I had a new sensor (ABS) fitted to the offending wheel, and it turned out to be the reluctor ring.
 
iCarsoft scan now tells me:
No CAN data received from control module N47-5 etc or from control module brake system.

So, now what? Does this means the ESP/ABS module is duff? Many people seem to have this problem
Thanks for any pointers
 

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iCarsoft scan now tells me:
No CAN data received from control module N47-5 etc or from control module brake system.

So, now what? Does this means the ESP/ABS module is duff? Many people seem to have this problem
Thanks for any pointers
Check the reluctor ring first
 
I found a French diagnostics website that is adamant that it is either the sensor or the ring. I have looked through the hole and see no signs of rust or anything and it seems to be the magnetic type rather than the toothed type so it looks like I will have to bit the bullet and remove the hub. since I already replaced the sensor with a new one.
If it is duff, how does this happen if it is not rusted and is magnetic? Seems odd

thanks
 
Anyone point me to any sites where there is a step by step guide to removing the hub totally or partially to replace the ring? There are a couple of Youtube videos but they are not too clear or the audio is unintelligible.
thanks

I have the WIS but it is not really much use either!
 
Anyone point me to any sites where there is a step by step guide to removing the hub totally or partially to replace the ring? There are a couple of Youtube videos but they are not too clear or the audio is unintelligible.
thanks

I have the WIS but it is not really much use either!
Put the new sensor to one side , it may be doa. Swap the left and right sensors over , if the fault moves it is the sensor otherwise the ring.
 
I tired a variant of this using the iCarsoft tool and telling it the car was LHD or RHD but the same wheel was shown at fault. I should probably do it properly as you mention! :)
 
I went through the same process, it was easier in the end to buy a new knuckle with the bearing already fitted, you will need a press and it must be fitted carefully and the right way round.
I got mine from Mercedes Edinburgh, came next day, fitting was easy.
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Still not out of the woods. I cleared all DTCs using iCarsoft expêcting that the car would show no warning lights but it did even though it was neither moved nor started. Why?
I also tried the trick of using magnets attached to a drill to rotate in front of the sensor to see if the sensor circuit worked but it didn't work. I don't want to attempt dismantling the hub until I a,m sure the ring is duff. Any suggestions?
Obviously if all else fails I will go to the dealer but this is now a challenge! I am still perplexed as to how a magnetic ring fails and also why the WIS states 'do not hammer the ring into place' but all the videos and guides I can find use a hammer
 
Still not out of the woods. I cleared all DTCs using iCarsoft expêcting that the car would show no warning lights but it did even though it was neither moved nor started. Why?
I also tried the trick of using magnets attached to a drill to rotate in front of the sensor to see if the sensor circuit worked but it didn't work. I don't want to attempt dismantling the hub until I a,m sure the ring is duff. Any suggestions?
Obviously if all else fails I will go to the dealer but this is now a challenge! I am still perplexed as to how a magnetic ring fails and also why the WIS states 'do not hammer the ring into place' but all the videos and guides I can find use a hammer
Have you removed the new sensor and swapped the old ones left/right ? What was the result ?
 
The only way to try it is to swap the sensor around, if the fault stays at the rear offside then it must be the bearing or reluctor ring.
It could also be damaged wiring or connector, but doubtful.
Why haven't you done this yet ?
 
Why hadn't I done this yet - laziness and thinking I could diagnose in a different way.
However, this morning I took off the right rear sensor (which works) and replaced it with a new one and tested. It works still but the left rear doesn't.
I fitted the old right rear sensor to the left rear and lo and behold, it works!!! When I switched on the ignition, all the warning lights had gone and when I started and tested wheel speeds, all seems to be OK.
So, at least I know it was never the impulse ring on the axle and it shows that the new sensor was either DOA or had a bad contact which by changing a jigglin I have managed to make good. There is only one contact anyway which is up in the wheel arch where it plugs in. Perhaps the old sensor had a loose connection too.
Anyway, now for a test drive...
And btw, thanks for everyone's tolerance and advice for a stubborn bugger like me..
 
Last edited:
In cas anyone ever needs to get at the impulse ring, this video is excellent and he removes the hub and gets to the ring without even removing the brake caliper! Excellent

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