W221 abs ring (reluctor?)

[BrianMcC]

Hope this is in the right place, I've posted on a few forums without much luck so hopefully somebody here can help

I have taken the plunge and purchased a 2006 69,000 mile S320 CDi

Now as the car has not done a lot of miles and did lie up for a bit so I have been slowly working my way through various gremlins (most fixed with a new battery) - however one that has not gone away is the occasional fault about the ABS not working etc - my mechanic had it narrowed down to either a faulty sensor or the ABS ring on the rear axle - after testing the sensors and finding them ok, he got a good look at the ring and says its corroded and would need replaced

Before I go into that is there anything I need to know - ie how hard is it to get at the ring, any special tools needed and what sort of strip down is needed - I am considering doing both rears at the same time as if one is bad the other can't be far behind - we did clean it a bit and it helped for a while but the errors are back again. any pointers would be helpful

 

[zipdip]

Hi there I have the same car you can get problems with the wheel sensors,this can throw up a ABS fault,you changed a battery was it the starting battery or the big one behind the rear seats accessed by the back of the boot,with a car like the w221 being left standing for a while the battery can throw up all sorts of weird electrical problems,I have always taken mine to a indy who has sorted out the few problems I have had.

 

[BrianMcC]

Yes I replaced the one behind the seat - In this case we know (from a visual inspection) that it is the ring that's faulty I'm just looking to find out how difficult a job it is

 

[selphy]

On my S211 with Airmatic I opted to take it to my local garage and it was a 2 or 3 hour job for them. Quite a lot of suspension links to remove. Can't imagine it is that different on a W221.

You need new hub nut and a new ABS impulse ring. Also, if you're unlucky the impulse ring could have broken and started grinding against the ABS sensor itself which will eventually wreck it. The root cause of the problem is that the outer ends of the rear driveshaft corrode and the rust forces the ABS impulse ring out of place.

Probably should get the wheel alignment re-done afterwards. I haven't bothered.