1995 C Class - Weird ABS problem

[jools182]

I was driving yesterday and went over a sharp bump in the road, then noticed the revs were going up and down by 100-200 revs as though I was moving my foot up and down on the accelerator. It stopped after a couple of seconds

Later on I was going over some speed bumps and when the rear of the car came down over the bumps, noticed that the car felt like it was slowing down slightly, I then noticed the ABS light was coming on for a second when hitting the bumps

Any ideas? Sensors or something?

 

[television]

I would wait and see what happens on this, probably a sensor, the rear rings can rust and maybe a clean up would help

 

[wireman]

On some models the OVP relay provides 12v power to the idle control unit, this maybe so on your car too.
I am not familiar with your cars fuel injection system but suspect that the OVP relay is faulty. Find the OVP and ensure the fuse in its top is in good order and that its fuse holder is clear of corrosion.

I have seen more intermittent ABS problems as a result of poor soldering inside the OVP relay than sensor or reluctor ring troubles. What Malcolm posts about rusty rings and dirty sensor tips is a valid point, on some models the rear rings mounted on the diff output flanges rot away, checking and cleaning them up would be a good idea.

There are several postings about ABS faults on this forum have a search around for more details.