Rain sensing not working after new windscreen

[DougieHolmes]

Hi there

I have a 67 plate C350e which 2 weeks ago had the windscreen replaced after a brick hit it.

Since the windscreen was replaced I've not really driven it in rain until yesterday when it became obvious that the windscreen wipers at position 1 and 2 on the stalk aren't working. They swipe once when I turn the stalk to pos 1 or 2 but nothing else... position 3 is continuous and that works. Auto lights work....

So... the windscreen people were a bit of a nightmare... the guy was clearly in a rush and having noticed that the screen had frozen on the inside 2 days after fitting it took a number of days for me to get an explanation that actually this is normal in very cold weather and is caused by the glue condensating as it heats and goes off - their answer.. use the car.. get it warm and it'll go.... and to be fair it did... but it took several days of phone calls to get through to a technician who could help.. so.......... the wipers

Ive made the call again and its clearly going to be days before I get an answer again. This morning.. Ive taken the cover off the rear view mirror... just to see if it was something as simple as a connector not being in place and Ive seen this (see pic).. the top left connector with the 2 solder points. Im kinda wondering what that is and if its the rain sensor... because if so......... its got nothing plugged into it.... and thus.. the cable could be in the roof lining... I haven't dug around for it yet, I thought Id come and see what everyone thought first.

Any ideas please?? thanks in advance!!

 

[brucemillar]

The rain sensor probably needs calibrating (mine did) it should plug into something but I’m not sure exactly what that something is in your pic.

I would tell your insurer that you want the windscreen properly replaced and calibrated.


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[DougieHolmes]

Yeah.. i agree they should sort it out, but it just seems such a hassle with the windscreen people.... I had hoped that the top left may be the sensor for the wipers and the fitter has just left it un plugged..

 

[markjay]

The rain sensor uses a photoelectric cell to determine if there's water on the windscreen (the light changes when it goes through water), and as it's an optical device it will need calibrating when relocating it from one windscreen to the other.

On some model the housing also hosts the forward-looking camera (in use by some driver aid systems) in which case this will need calibrating as well.

I am not sure where the light sensor is though (for the automatic headlights) - but if it's in there as well, then this too will need calibrating.

And I think the fitter will need STAR for the calibration, so possibly a dealer-only (or specialist) job?

Either way, anyone fitting windscreens for a living should would have had this issue before and sould know what needs to be done.

BTW, I was told that original windscreens supplied by MB come with all the gizmos already fitted to the windscreen and pre-calibrated - can anyone confirm if this is indeed the case?

 

[brucemillar]

The rain sensor uses a photoelectric cell to determine if there's water on the windscreen (the light changes when it goes through water), and as it's an optical device it will need calibrating when relocating it from one windscreen to the other.

On some model the housing also hosts the forward-looking camera (in use by some driver aid systems) in which case this will need calibrating as well.

I am not sure where the light sensor is though (for the automatic headlights) - but if it's in there as well, then this too will need calibrating.

And I think the fitter will need STAR for the calibration, so possibly a dealer-only (or specialist) job?

Either way, anyone fitting windscreens for a living should would have had this issue before and sould know what needs to be done.

BTW, I was told that original windscreens supplied by MB come with all the gizmos already fitted to the windscreen and pre-calibrated - can anyone confirm if this is indeed the case?

When I got a new OEM front screen in my C55 it came with no sensor. This had to be purchased (not expensive) fitted (two minute clip in) and calibrated by MB.


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[DougieHolmes]

ahhh that's what I'm worrying about now.... that there is no sensor fitted.... im just waiting for the windscreen people to call back and see which month they can come and look at it again...

 

[whitenemesis]

Who are these windscreen people?

 

[markmifsud]

I had my glass replaced by AutoGlass at Christmas and he tested the rain sensor function prior and post replacement. I was chatting to him, (as you do) and asked about what they do about cars that have a complicated setup that needs calibrating and he said they do have a special team with the correct equipment for just those occasions.

 

[DougieHolmes]

so... its all sorted.. the technician came out after my 400th phone call and rant and it was the sensor not positioned in its housing correctly.. essentially it was too far off the screen... all sorted now and unlike before tested and shown to me..

 

[markjay]

so... its all sorted.. the technician came out after my 400th phone call and rant and it was the sensor not positioned in its housing correctly.. essentially it was too far off the screen... all sorted now and unlike before tested and shown to me..

Any apology for not fitting correctly first time, per-chance?

 

[DougieHolmes]

Do you know what.. there was actually... the technician that sorted the issue was different to the original fitter and was very apologetic. Lesson learnt though.... get them to prove to me pre change that its working and then get them to show me after its still working..

 

[DougieHolmes]

Thanks everyone for your help with this too!!.. my first post with an issue and you all came to the rescue!!

 

[400ixl]

Even with the sensor positioned correctly it should still be re-calibrated. This should be a standard part of the service, be it that part at the Mercedes dealer as the Windscreen replacement company won't have the tools.