ABS and traction control warning

[scotty p]

Hi, I have had a Mercedes for a few years which has been pretty much faultless but has since developed a strange fault.

I managed to burst a brake line the other month which I replaced but that meant needing to bleed the brakes back up which was problematic to say the least, I just couldn't get the fluid back towards the pistons. I know you are supposed to open the ABS module electronically but eventually I got it to flow by pressure bleeding them up and the brakes work fine now.

However before I used the pressure bleeder I decided to spin the back wheels of the car whilst it was on stands to see if the rear brakes were doing anything at all. Now obviously the car though the back wheels were moving but the front ones weren't and it immediately threw up a traction control error and cut the power. I switched off the ESP and carried on but ever since then the ABS and ESP warning have been on and won't go off.

I'm sure I didn't damage any wheel sensors when messing around with the brakes and what I did cant be any different to spinning the back wheels on ice or similar. Why would the error be constantly there? Also note that the error popped up before I used the pressure bleeder so it can't be that thats caused the error.

Thanks for any insights.

 

[scotty p]

OK I've narrowed this down to the ABS ring on the left rear axel, I'm having trouble locating a suitable replacement part, can the reluctor ring be fitted independently of the drive shaft. its a 2008 W204 C180K?

 

[EmilysDad]

I bought reluctor rings for my Smart from this place. They were the second rings I'd fitted, the first set though much more expensive fitted like the proverbial in a sock. These fitted perfectly. MB only sell a complete drive shaft for the Smart.

Abs Reluctor Mercedes C Class for sale | eBay

Find great deals on eBay for Abs Reluctor Mercedes C Class. Shop with confidence.

www.ebay.co.uk

 

[mattkh]

............ I decided to spin the back wheels of the car whilst it was on stands to see if the rear brakes were doing anything at all. Now obviously the car though the back wheels were moving but the front ones weren't and it immediately threw up a traction control error.....

Was the ignition ON when you did the above..?

 

[mioba]

Rears are normally entire drive shaft for the want of a ring.

Have you cleared codes, restarted and see what new codes up.

What code reader are you using....

 

[EmilysDad]

Rears are normally entire drive shaft for the want of a ring.
.....

MB might not sell them but that doesn't mean you can get a reluctor ring from elsewhere and fit it ..... they are generally a tap on or glue on fit

 

[mioba]

MB might not sell them but that doesn't mean you can get a reluctor ring from elsewhere and fit it ..... they are generally a tap on or glue on fit

That be true

 

[scotty p]

Was the ignition ON when you did the above..?

Yes, I mean spinning them via the engine and in gear, so the back wheels were being driven in the air but the front ones were on the ground.

 

[scotty p]

Rears are normally entire drive shaft for the want of a ring.

Have you cleared codes, restarted and see what new codes up.

What code reader are you using....

Hi, I used an icarsoft mk1 to clear the codes, the error clears but as soon as you drive it the ABS fault comes back on. I did the live data on the wheel speed and the suspect wheel shows up as jumping about all over the place or not moving whilst the other three read the same speed.

 

[mioba]

is there i diagnostic m option on the icarsoft or just showing wrrors.

its either the sensor itself or the ring. The ring you can usually tell by the condition

 

[scotty p]

is there i diagnostic m option on the icarsoft or just showing errors.

its either the sensor itself or the ring. The ring you can usually tell by the condition

I'm no expert with it at all, on the menus I clicked diagnostics and then did a smart scan, it scanned every module on the car and a list of errors for them, I read and cleared all the errors and the ABS light went out but came back on as soon as the car was driven.

I did change all the wheel sensors hoping that would sort it without buying a code reader so all 4 sensors are new, it was only £50 for all 4 so I thought it was worth a shot. What goes wrong with the ABS ring though, its just a round magnet isn't it?

Thanks for the help btw.

 

[EmilysDad]

I'm no expert with it at all, on the menus I clicked diagnostics and then did a smart scan, it scanned every module on the car and a list of errors for them, I read and cleared all the errors and the ABS light went out but came back on as soon as the car was driven.

I did change all the wheel sensors hoping that would sort it without buying a code reader so all 4 sensors are new, it was only £50 for all 4 so I thought it was worth a shot. What goes wrong with the ABS ring though, its just a round magnet isn't it?

Thanks for the help btw.

The sensor 'looks' at a reluctor, which is a castellated ring on the drive shaft and gets a yes no yes no etc from the ring. If its rusted & split, the gaps are not consistent which confuses the ABS modules which then throws up a fault.

 

[LostKiwi]

I'm no expert with it at all, on the menus I clicked diagnostics and then did a smart scan, it scanned every module on the car and a list of errors for them, I read and cleared all the errors and the ABS light went out but came back on as soon as the car was driven.

I did change all the wheel sensors hoping that would sort it without buying a code reader so all 4 sensors are new, it was only £50 for all 4 so I thought it was worth a shot. What goes wrong with the ABS ring though, its just a round magnet isn't it?

Thanks for the help btw.

So cheap third party ABS sensors....?

Hmmm... Wouldn't be the first time we've seen problems with third party sensors.

If possible swap sensors side to side.

 

[mioba]

4 sensors for 50 pound, were they from a scrap car.

Experience tells me new genuine is the route.

As mentioned swap the failed side over and scan again

 

[mattkh]

I did change all the wheel sensors

When you did that, were you able to see the reluctor rings and did you clean them with a tooth brush..?

 

[scotty p]

4 sensors for 50 pound, were they from a scrap car.

Experience tells me new genuine is the route.

As mentioned swap the failed side over and scan again

It did have an ABS fault before I replaced any sensors though, I know its possible that it could have been a different problem and I solved that one by replacing the sensors but caused another one elsewhere by fitting cheap sensors but I think its unlikely and the original fault wasn't sensor related. I could be wrong though and will swap the two rear sensor first and see what happens.

 

[scotty p]

When you did that, were you able to see the reluctor rings and did you clean them with a tooth brush..?

Don't you have to take the hub off to get to the ring?

 

[mioba]

Just a thought, I had to replace the ABS control module on my W220 a few years back, having replaced the "defective" ABS sensor and the rings, the error still came back, MB checked with Germany and the solution was to replace the module, not cheap and needs coding to the car.

I mention the need for original sensors, mine lasted 14 years, i replaced with aftermarket and they failed within 1 years and a week....

 

[scotty p]

Ok, I've made a bit of progress on this, I've stripped it down ready and now the sensor is out you can see the ABS ring through the hole and it looks pretty bad, bits of it are missing as you rotate the hub. A question though, does anyone know the hub nut size, its a 12 point but my 36mm socket is too big, I've read that its a 30mm somewhere but that seems too small to be honest.

Also how do you get the handbrake cable off? I think it needs to be detached to get the hub off and it obviously goes through the back of the hub but with the actuator attached it won't fit through the hole.



That pin is the same on both sides, it doesn't unscrew or anything, do you really have to bend the bracket over it to remove it, I don't want to snap it, or does it drift out.

 

[scotty p]

Right I think I've solved this one now. Dismantled the hub assembly (hub nut size is 32mm BTW). The ABS ring was completely rusted away so that was obviously the problem, I couldn't find just the ring for sale so ordered a cheap drive shaft off E-bay. I couldn't find the correct shaft for my model of car though so took a gamble that most shafts would be the same so ordered one off a C220 diesel for £15.

It turns out that the shafts aren't the same and have different flanges and slightly different lengths so I decided to see if I could prise the ABS ring off the E-bay shaft, remarkably I managed to get it off in one piece with gentle tapping with a screwdriver and it fitted onto my original shaft perfectly. Fitted it all back together, cleared the code and this time after a short drive the warnings stayed off.