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1996 c200 auto, ABS light question

Discussion in 'Suspension, Steering & Brakes' started by zeaphod, Feb 16, 2011.

  1. zeaphod

    zeaphod Active Member

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    Belfast
    Your Mercedes:
    C200/1996/petrol
    My lovely C200 recently developed a permanent ABS warning light.
    The light came on after stopping, i.e. without moving off. It is now a permanent feature.
    I have checked the OVP output to the ABS control unit - 14.2v with the engine running.
    Am I right in thinking that because the light comes on before the sensors are activated, then it is more likely to be the ABS control unit than a sensor? - or will a short circuit or open circuit sensor cause this too?
    I have checked the physical condition of the front sensors and rings, all looks ok. I'm not too sure how to separate the front sensor plugs at the wheelarch - ping the wire clip off and pull hard?
     
  2. television

    television Always remembered RIP

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    Your Mercedes:
    2002 SL500, 216 CL500, all fully loaded
    It is more likely to be a sensor fault they are be far the most common. If a sensor is open circuit then the lamp will be on
     
  3. OP
    zeaphod

    zeaphod Active Member

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    C200/1996/petrol
    ABS sensor fault? -

    Thanks for the quick response Malcolm. I measured the resistance of the rear sensor at 180k ohms, which seems much higher than other mentions on this forum.
     
  4. OP
    zeaphod

    zeaphod Active Member

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    Your Mercedes:
    C200/1996/petrol
    rear ABS sensor resistance

    I see from a few other posts that the single rear sensor should read around 800 - 1000 ohms. Looks like a trip to the dealers tomorrow!
     
  5. television

    television Always remembered RIP

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    That is way over the top, I do not have the figure to hand, but as you say on here.

    Did you have a real good connection when you did the test, and if that is the value then to all intents and purposes it is open circuit
     
  6. bigasotonuk

    bigasotonuk Senior Member

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    Your Mercedes:
    C43/55 AMG 1999 / C230K 1997
    Hi,
    Have you got Euro car parts over in N.I.? As they will be cheaper than a main dealer, I believe you will need an ATE part, Euro car parts pt. no. 417 22 0500
     
  7. OP
    zeaphod

    zeaphod Active Member

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    Your Mercedes:
    C200/1996/petrol
    ABS rear sensor removal

    The new sensor was £66, not too bad. FYI the resistance of the new is 1008ohms.
    I've spent the morning trying to remove the old sensor. 5mm allen key removes the clamp bolt, but the bugger refuses to come out more than 5mm. Time for a pint, more force will be applied this afternoon. ;)
     
  8. OP
    zeaphod

    zeaphod Active Member

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    Your Mercedes:
    C200/1996/petrol
    stuck rear sensor

    applied more force, still stuck. hard to believe it's just the o ring holding it in.:(
     
  9. OP
    zeaphod

    zeaphod Active Member

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    Your Mercedes:
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    still stuck

    still stuck. after 25 years of working on cars, i'm baffled. turns by hand, but will not pull out. have i missed something?
     
  10. OP
    zeaphod

    zeaphod Active Member

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    nasty plastic

    and whoever designed the plastic cover over the evaporative emissions control cylinder was an evil genius. almost impossible to get at the bolts. almost defeated, the remains of the existing sensor are offering little purchase for the vise grips. drill and lever?
     
  11. OP
    zeaphod

    zeaphod Active Member

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    Your Mercedes:
    C200/1996/petrol
    the train is coming - light at the end of the tunnel

    Illumination: 10mm socket on the end of extn bar removed the placcy cover.
    The sensor is still stuck - moved out another few mm after an hour. The new exposed part is covered in corrosion, which makes me think that the metal end is rusted in the diff.
    Any experience/ideas appreciated. I really don't want to disconnect the light for the MOT.
    Wish I had a set of ramps and decent lighting. Ah well, off for the night.:(
     
    Last edited: Feb 18, 2011
  12. OP
    zeaphod

    zeaphod Active Member

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    Your Mercedes:
    C200/1996/petrol
    rear diff sensor removal

    Finally removed the rear sensor this afternoon, after days of working at it. :D
    I ended up having to drill several holes deep into the old sensor and lever/pick bits out.
    Right up to the last moment I thought it wasn't coming, then out it popped.
    Be careful not to drill right through the sensor - you dont want any swarf round the reluctor ring in the diff.
    Getting the drill at it involved dropping the fuel pump and removing the fuel pump support cradle - both came off easily (10mm nuts).
     
  13. television

    television Always remembered RIP

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    So sorry you have been working alone on this,,I can recall someone else having the same problems, congratulations any way :D
     
  14. OP
    zeaphod

    zeaphod Active Member

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    thanks

    Thanks for that Malcolm.
    A great feeling of satisfaction when the ABS light went off.
    It did take a mile or so after re-fitting, something for anyone else to take note of. Just plugging the sensor into the loom will NOT extinguish the light.

    P.S. Had the car up to my local MB specialist this afternoon - they agreed with me on the "fun" to be had with this job.
     

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