New Screen Fitted... No Rain Sensor Anymore

Discussion in 'Electronics' started by SheepLady, Sep 12, 2008.

  1. SheepLady

    SheepLady New Member

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    Hello... I'm new to MBClub UK... so Hello...

    To keep this short, as this has been going on for 2 months....

    We have a 1997 280S - WITH rain sensor - and then...
    Windscreen cracked
    New one fitted
    Rain sensor didnt work any more
    Reported it to screen fitters
    They came with new screen, but didnt fit it cos their test with squirter bottle showed sensor was working (when the rearview mirror was hanging down)...
    When mirror put back again, sensor not working properly
    Rain sensor erratic from then on
    Wiper wiped 5 times at switch-on instead of 1 wipe
    It wiped when it wasnt raining
    It didnt wipe when it was raining
    Then it went on to intermittent
    New sensor fitted by Mercedes (at screen fitter's request)
    Wipers still working at intermittent
    Wipers dont work any different when it is raining to when it is not
    Water squirted at screen does not make sensor kick in either

    Every time the rearview mirror has been taken off and put back on again, the wipers work differently - erratically on sensor - or intermittent, with no sensor

    Screen fitters tell me its the wiper stick on the steering wheel probably at fault - so that means the car was about to have a fault when they fitted the new screen.
    Mercedes however (another branch) tells me on this model, the sensor works or it doesnt work - if it doesnt, it is the screen at fault

    Screen fitter tell me they will fit an MB screen as this will probably fix it - then they wont fit an MB screen because it makes no difference - all screens are made to the same spec

    Does this ring any bells with anyone please? Would be SO grateful to hear what you think...

    Thanks...
     
  2. whitenemesis

    whitenemesis MB Club Veteran

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    When MB fitted a new sensor did they adapt the sensor to the screen? i.e. recode using STAR?

    If the auto wipers worked before the new screen and now don't, it's down to the screen fitters to sort out. Insist they sort it.
     
  3. OP
    OP
    SheepLady

    SheepLady New Member

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    Autoglass said when they fitted the new screen, the sensor would have to be recoded...

    MB say that this model is not one that is recoded... both when the new screen was fitted and again when the sensor was fitted... Does this mean this model is too old!?

    I am continuing to insist and this will soon come to a head!!!
     
    Last edited: Sep 12, 2008
  4. whitenemesis

    whitenemesis MB Club Veteran

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    The sensor MUST be adapted to the new screen.

    It worked, now it doesn't... something has changed!
     
  5. OP
    OP
    SheepLady

    SheepLady New Member

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    One Autoglass manager told me that the sensor worked with the tint and he is the one who said an MB screen would probably fix it as a slight tint difference might just tip the balance.

    Someone from Head Office told me today that tint has nothing to do with it at all. It has to do with the thickness of the screen... and when rain falls on it, it changes the thickness, thus making the wipers work...

    ... or something like that.

    I am told that there is no reading for a sensor... How can I tell a dealer there is...

    I hope I can get enough info from this site to be able to do so!!!!
     
  6. whitenemesis

    whitenemesis MB Club Veteran

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    The tint makes a HUGE difference!

    That's the whole difference of doing an adaptation with STAR.

    Yes the rain changes the refractive index of the screen but that's what STAR is suposed to account for....
     
  7. OP
    OP
    SheepLady

    SheepLady New Member

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    Thanks for your help so far!

    I have just spoken to our mechanic who does work on the car. A couple of days ago we took it to him and he put on his "Omni Scan" diagnostics machine. He said there was no sensor reset facility found. Is this what you mean by STAR? He says this Omni Scan is what the AA and RAC have.

    Yesterday, I arranged to meet up with this Head Office chap at my local Autoglass. He will bring with him a new screen (NOT MB, as he's the one who says tint has nothing to do with it). But it wont be fitted unless it is proved that it's the screen at fault!
     
  8. Howard

    Howard MB Club Veteran

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    STAR is the specialist computer system used by MB ( and good indys ) to talk to and work on the cars , fault find , and reset sensors .

    Unlikely that AA or RAC would have it.
     
  9. OP
    OP
    SheepLady

    SheepLady New Member

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    OK... thanks... Just trying to get re-confirmation from the Merc dealer who fitted the new sensor... which wasnt needed incidentally :)... but they did also say last week that this model didnt need re-coding.

    This is going to come to a head on Thursday... so I would be grateful of any info anyone has...
     
  10. pammy

    pammy MB Club Veteran

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    Have you done this through your insurance and was it a fitter they provided? If so I'd be tempted to go to them and let them know about the poor quality of work and see what they say.
     
  11. OP
    OP
    SheepLady

    SheepLady New Member

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    Pammy... yes and Autoglass was their nominated fitter. I have spoken to the broker who has said keep them informed and she has kept a log. I'm not sure if she's actually contacted the insurance company yet but has said she would... but I seem to have kept the ball rolling even though slowly. I think if nothing is accomplished Thursday, then things will take a turn cos I'm pretty fed up with this now.
     
  12. pammy

    pammy MB Club Veteran

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    Cut the broker out - it's an unecessary third party - go direct to the insurance company yourself and let them know how unhappy you are and ask what they propose to do about it.;)

    Welcome by the way
     
  13. OP
    OP
    SheepLady

    SheepLady New Member

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    Hmmm... good idea... thanks.... Do you think I should push for an MB screen? I was told twice by Autoglass they'd fit one, now this newest contact has told me there's no point as they're all the same...
     
  14. pammy

    pammy MB Club Veteran

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    Yup - insist on one.
     
  15. grober

    grober MB Club Veteran

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    this is a description of a how a rain sensor works in a 99 SL - I doubt your system is much different?

    The sensor appears to be located on the windshield, in front of the rear-view mirror.
    The rain sensor (B38) senses moisture on the windshield. When the combination switch (S4) is in the interval position the rain sensor (B38) controls the interval time.
    When the combination switch (S4) is switched on or when power is switched to terminal 15R when the combination switch (S4) is already in the interval position, the wipers are actuated one time, even when the windshield is dry.
    The rain sensor (B38) is connected to the multi-function control module (N10) or to the combination relay (N10/2) by a serial data bus. The multi-function control module (N10) or the combination relay (N10/2) sends a request to the rain sensor (B38) via the data bus. The rain sensor (B38) answers each request. The moisture on the windshield is measured by an optical element operating with infrared light. If the windshield in the area of the rain sensor (B38) is dry the light is reflected completely. If the windshield is wet in the area of the reflection surface the light is dispersed. The percentage of light reflected decreases as the moisture increases. This light reflection serves as the variable for control of the interval. If the rain sensor (B38) recognizes that the window is "moist", the multi-function control unit (N10) or the combination relay (N10/2) actuates the wiper motor (M6/1)."

    If your system is like this it would be highly dependant on the refractive index/thickness of the windscreen glass. In the absence of any software adjustment of the sensitivity the only thing you can do is to change the windscreen to the approved type.
    Yet another reason to always specify a MB replacement windscreen!
     
  16. OP
    OP
    SheepLady

    SheepLady New Member

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    This sounds just what I need... I shall email this to Autoglass and hope he sees the light. To be honest, I have never had a windscreen go on me. This is a learning curve so next time I will be more prepared.

    This time however, I am very pleased I found this site and a lot of experienced MB people! Thank you...
     
  17. OP
    OP
    SheepLady

    SheepLady New Member

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    There's also screen noise... I dont remember this before... Is this common with generic screens or has it been badly fitted? I've looked at it, and it looks OK to me, but could there be something I'm missing...
     
  18. lynall

    lynall Hardcore MB Enthusiast

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    I had a new screen on my e class a couple of weeks ago and all the bloke asked me on the phone was what spec (avantgarde) and did it have rain sensors (yes) and all has been fine since exactly as before.



    Lynall
     
  19. BarryS

    BarryS Hardcore MB Enthusiast

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    I had a new screen last year - they don't generally fit a MB original screen due to cost but the version fitted seems exactly the same, same Avantagard colour tint etc and rain sensor works OK. So I don't think your problem is that the screen is not a MB original.
     
  20. OP
    OP
    SheepLady

    SheepLady New Member

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    My own old sensor works strangely (wipes 5 times on start up) - the 'new' one fitted by Mercedes, doesnt seem to 'sense' at all... I am having a Mercedes screen fitted so I hope after over 2 months, that this sorts out the problem...
     

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