i have a 97 e-class. The windscreen was recently replaced by Autoglass due to stone crack. Even though the rain sensor has been connected up (and checked by Autoglass) the wipers run continually when put onto the intermittent (rain sensor) setting - even when dry! I have cleaned the windscreen but no joy.
all Autoglass say is take it to a Mercedes main dealer.
Any thoughts or help??
thanks.
addick.
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I would say that they have either damaged the sensor or trapped the cabling causing the circuit to make constantly.
Tell Autoglass that you will take it to M.B.s to look at it and if it is found to be there fault you will pass the bill onto them.
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Is this the optical sensor unit that fits on the inside of the windscreen? If so then there may be dirt on the inside of the screen in front of the sensor emitter and receiver - or maybe its not stuck on properly.
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Yes - it appears to be an optical sensor on the inside of the windscreen just behind the rear view mirror. There is a cord and optical unit which clips onto a housing actually stuck to the screen itself.
Autoglass took this apart and checked it and said they could see nothing wrong.
How do these things work? Is it worth me taking the thing apart or not? Autoglass suggested Mercedes could "re-set/re-programme" the "chip" which controls the wipers. Don't know if this is right!!
Addick>> Is this the optical sensor unit that fits on the insideof the windscreen? If so then there may be dirt on the inside of the screen in front of the sensor emitter and receiver - or maybe its not stuck on properly.
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The sensor works by using the fact that the refractive indicies of glass, air and water are different.
Light shines on to the screen at a 45 deg. angle and, with a dry screen, reflects back to the sensor receiver.
When the glass is wet a certain amount of the light is refracted away from the glass and not reflected back to the receiver. I think they are made by Temic (Telefunken microelectronics) - you might try a web search for more details.
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The wipers have gone into default mode. Merc have the technology (ie the correct software) to re-set the sensor to that particular screen.
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Thank you.
Is this something Merc do on the spot or is it a couple of hours off work situation?
What will they charge me?!!
Addick
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I am sure glass-tech is correct. Different glass has slightly different properties so the sensor will need to be calibrated to your new screen. I am sure that the sensor's processor unit will have a calibration mode - it is just a case of activating that. I don't imagine it would be more than a few minutes work - but who knows what an MB dealer would charge (tried to charge me £95 to set tracking on a C-class about 7 years ago, when their labour rate was about £45).
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Aprilia
Sorry I meant to say in my first mail, the sensor is made by a company called Kostal, I've tried on many occasion to talk to them about the technical spec of these sensors ( used on many makes of car ) but to little outcome. I did get an answer a couple of times from one chap, but his bosses put a stop to him talking to me. The main problem is that Merc hold the licence to this part and will not give out any info, because they see us as competitors, but how many screens do they fit ? none. We fit Thousands a year ( just under 18.000 Merc windscreens in the last 12 months ).
Your right it would only take a few minutes, they charge around £65 for the job.
Addick talk to your local Autoglass, It will get sorted.
Aprilia
Could you contact me, I would be very interested in talking to you about a project we have on going at the moment regarding the technology in modern cars.
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Ah, its a Kostal part is it? Kostal is one of those companies that's been around since the dawn of time and makes loads of automotive parts, but no-one's ever heard of it!
If I'm not much mistaken they make these rain sensors in southern Ireland. I'm surprised that Merc. hold the licence because I think basically the same part appears on other cars (e.g. Alfa, BMW). Does the one on the Merc. also switch the lights on when it gets dull?
Glass-tech - I will send you and e-mail ref. your query.
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Kostal make 2 sensors, a 1st generation and a 2nd generation. the second generation has the light sensor, very hard to tell the difference from the outside of the car. But basicly they are used on similar models from 2002 on.
Its a good point about the licence, I'll have another go at talking to them about technical specs.
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Fascinating set of info about rain sensors. I have a rain sensor on my VW Passat and I'm not impressed. It doesn't seem to react very well, particularly at low speeds. In fact I wouldn't mind changing it to the normal intermittent wipe system - is this possible by reprogramming the system?
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I have a related problem with the rain sensitive wipers on my Peugeot 206. Driving at a steady speed and in steady light rain the wipers vary between intermittent and 4 wipes rapid. 2 other people I have spoken to have the same problem and Peugeot say that is the way they are! I never had trouble with my Merc ones but I never had a screen changed either!
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I think cars are getting too complex for their (and their owners!) own good!
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I have always thought that intelligent variable speed/frequency intermittent wipers would be better if they monitored the current taken. This will be dependent on motor loading, ie on wetness of screen. This could also be capable of 'learning' if combined with input of driver requests for a single additional wipes.
Another project idea with no time to do.....
pmh (was peter)
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I like the variable intermittent wipers in the Fiesta, they can quickly and easily be altered, anything from 1 second to about 20 odd seconds. Personally I find myself using the 1 second wipe cycle more than the continuous, which can be a bit too much if it's not raining hard.
Blue
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I seem to have 9 optical sensors on the windscreen of my Merc and the whole systems works very well. You just set it to auto and leave it and it will adjust very well.
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