Either disconnect the computer OR either of the relays at the HYDRAULIC unit..under the black plastic cover.

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MERCEDES Benz Master Guild Technician (6 TIMES)
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Retired Moderator

I realiize this is an old thread, but I'm now having additional braking issues and am trying to eliminate the ABS as the source. I'm getting a shuddering or vibration like driving over a corrugated pavement, mostly when the brakes are applied at high speeds, like 60MPH +, and not all the time or necessarily at high speed, as it does this sometime at 40MPH or so too.
It's not a warped rotor, as the vibration is not felt at the pedal. I pulled both front calipers and the rotors spin true, one pad is worn more than the other on the driver side (suggesting a sticking piston on the other pad maybe, leaving the worn one to do the work?), and all pistons can be easily retracted with a C clamp.
Since I've had a previously noted problem with the ABS (see earlier post this thread), I'm thinking that the vibration is caused by the system activating erratically or from a bad sensor signal(s), so I'd like to test to see if braking is normal with the ABS bypassed.
My questions:
- Would pulling the 2 relays from the control unit change the braking system to standard non-ABS hydraulics, and are there any negatives to doing this?
- What is the difference removing only one of the relays, as opposed to both, or is there no difference?

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1986 560SL
2002 Toyota Camry
1993 Lexus

I have a similiar problem (scrunching brakes at slow speed) with my 93 300 TE. It is worse in the winter and better in the summer. My mechanic believes this is because newer brake pads are made out of new materials (including pieces of metal) which wear differently and have different friction coefficients; this confuses the computer. His advice was to brake very hard from 50-60 mph down to zero every so often to smooth out the brake pads. Using this technique we have been able to manage (not eliminate) this problem.
Regards,
Steve

Wow, this is an old thread, I cannot believe it has been over 10 years since I originally posted this, but thought I would just share here instead of a new thread.

That '85 380SE is long gone. I never did figure out the ABS issue on that, but I later purchased a '88 300SEL in October of 2008, which we actually still own. It is now my moms car as I gave it to her around 2012.

The ABS brakes were fine until my dad changed the front brake pads around 2010, then it started doing the same thing as my 380SE. When going down the drive going slow, the ABS would activate and kick the pedal up then during driving the light would eventually come on. It has went through another set of pads since then and wearing down the pads never changed anything. I am guessing he damaged a connector or something when replacing the pads. It is going to their mechanic soon for some front-end work so I may have him check the ABS connectors as well if he can and perhaps clean them and see if that helps. I think 6 years is long enough to be dealing with this.