When I first start my car and sometimes at random intervals driving it, my ABS control unit make a clicking noise, almost like a fan hitting something (but obviously not). I am 99% positive that it is coming from the ABS control unit as I can feel it vibrating when its making the noise. I can also feel the clicking/virbations in the brake pedal when I can hear the noise. Like I said, its very occasional and only lasts for 30 seconds at a time (or so). The brakes work well and none of the dummy lights are on in the instrument cluster. Any ideas what might be causing such a noise?

I searched on quite a few different terms and couldn't find much related to this problem.

Usually when an ABS pump kicks in you will feel the pulsing, this is the ABS Pump doing its work. I only notice mypulsing or ABS activation during hard braking or when I am on ice or snow. If it is doing it during normal braking you may have a malfunction in your braking system. A malfunction can be anything from a sticking caliper to unequal pressure, but it seems to me that you have a wheel that is potential to locking and the ABS is kicking in. Could be a speed sensor too. I would get the brakes checked to ensure everything is ok. Good luck!
Brian

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Brian W. Heitman

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I think that you're misunderstanding what i was trying to describe. My ABS is NOT being activated when the clicking noise is present (or ever under normal braking conditions). I know the pulsing feeling of the ABS and this is quite different. The ABS unit is making the noise and i can feel the noise just a little but in the brake pedal (it vibrates just a little). Like I said, it doesn't happen very often and only for about 30 seconds at a time maybe 2 or 3 times in a 20 minute trip (sometimes never).

in my 89 190e 2.6...

However, I may be facing an OVP relay issue which causes my ABS light to come on very occasionally...and causes my car to stall intermittently.

From time to time, and usually when I apply the brakes upon the first stop after pulling away, the brake slightly pulsates and I can hear a clicking noise. It may happen at other times during the drive as well.

My brakes are quite spongey so I'm chalking this up to a pad/rotor isssue, and not a malfunction of the ABS system...although you never know. I'm gonna pull the wheels and check the pads and front pad sensors to see if there is an issue there.

I'll let you know what I discover as it may shed some light on your situation as well...however, in the meantime, please reply here or email me at kevock@amnh, if you happen upon a solution to the problem.

Sorry, I cant be of more help as I'm piggy-backing on your problem.

Ok, so I am positive that it is coming from the ABS/ASR pump. It makes a clicking noise as if the pump needs to be oiled or lubed in some way. I'm not sure why its doing this or what effect his has on the ABS/ASR systems as they both seem to be functioning properly - i've tested them As I said earlier, neither the ABS or ASR dummy lights are on and the pump only seems to do it a few random times while driving (ie. I can not reproduce the noise by doing anything)

On a related issue, how (or does it at all) does the ABS pump interact with the ASR system. Looking at other e320's:


This e320 is without ASR and seems to have a "normal" sized ABS pump (common to many other w201/w124 cars)

My pump/unit on the other hand is enormous compared to that one (seen here for sale on ebay for 275):



and here on a wagon w/ASR:

no one has had a similar problem?? Am i just left to fork out the cash and replace the pump with a used unit?