Parts Catalog Accessories Catalog Tech Info Tech Forums
  Search our site:    
 Cart  | Project List | Order Status | Help    

Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

LinkBack Thread Tools Display Modes
Old 09-19-2001, 04:11 AM
Registered User
Join Date: Feb 2001
Posts: 7
Question Antilock Brakes Not Working Properly

Hello All,

I have found that I am able to lock the brakes on my '96 W202 (C220). Normal braking is good (I am aware ABS is failsafe so normal operation occurs even if ABS goes out). Dash light operates as it should- it comes on when car is started, but goes off shortly thereafter and is never intermittent. When I brake quickly and with a lot of force I can tell something is going on with the ABS (fast, but far too light/very mild puslating sound/feel, no real kick from the pedal as is supposed to be normal). Then it seems (one or more of) the wheels lock and the car skids. An excellent independent Mercedes mechanic retrieved two front sensor codes, tested/cleaned each sensor, and cleared the codes. The sensors give proper voltage when the wheels are spun. He then road tested the car and found the same problem. It seems that the ABS immediately kicks in, but not fully, and then it cuts out and the wheels lock. He said the REAR ABS seems to work. When he got back to his shop he re-checked for codes and found none! He set up another appointment for me for further diagnosis. Since I am feeling something different from normal braking, I'm guessing the ECU is receiving signals from the sensors, and it (ECU) is triggering the hydraulic unit, but either the solenoids/valves/pump is/are weird.

1) Is it possible that the overvoltage protection relay is not feeding adequate voltage to the ABS ECU to properly trigger the system? I have suspected possible weirdness with this (occasional small idle drop/return). The part # is the new one I think)

2) Would air in the ABS hydraulic unit cause these symptoms?

3) Are the ECU and ABS pump capable of "partial" operation (thus the mild pulsation)?

4) Why does the dash ABS light work normally, and no fault codes show up?

I have scheduled an appointment for further testing for next week, but I am really puzzled and would really appreicate any insights any of you can offer. I'm hoping I don't need a new ABS pump or ABS ECU! Thanks so much.

Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Mechanical Fuel Injection Pump not working properly M_Anker Vintage Mercedes 12 06-06-2004 12:40 PM
82.5K Service , 90K service...& .... brakes when yosshimura Tech Help 8 05-20-2004 10:36 AM
Left head light is not working properly... RolexBenz190E Tech Help 5 03-09-2004 12:33 PM
Anti-lock Brakes working when not supposed to.... RLNAMERCEDES100 Diesel Discussion 1 07-23-2002 07:15 PM
Antilock light on RAE190 Tech Help 3 03-20-1999 11:51 AM

All times are GMT -4. The time now is 08:51 AM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page