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2004 SLK200
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Discussion Starter · #1 ·
Photos of the rain/light sensor area. The windscreen has been replaced just before I bought the car as there was a nasty scratch on the driver side. The close-up photo looks a bit odd. The wipers don't react to rain, but I'm not sure if the car was ever equipped with the rain sensor. There is on photo with flash showing the red dots, one in the daylight and a close-up of, what I believe, is the light sensor.

What I'm looking at? Is it a rain/light sensor combo?
Is the transparent "glue" applied correctly?

Edit: sensor part number is A 171 820 15 26 so it's 3 wire rain & light sensor. It's broken, incorrectly glued or not enabled and I'm going to fix it >:D. Photo below.
 

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Founding Member 2006
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does your datacard say you have the rain sensor?
are you testing it when it is not raining? if so, make sure the doors are closed
have you cleaned in the sensor area to remove any dirt from the sensors
if the windscreen has been replaced, they might have used the wrong windshield thus blocking the sensor

http://www.slkworld.com/slk-r171-ge...ld-replacement-good-bad-ugly.html#post1501001

so start with your datacard.
 

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Discussion Starter · #3 · (Edited)
Data card - no rain sensor (thanks again for the data card!)
Part number - rain sensor present >:D
Windscreen - check in progress, but there were some problems as they ordered wrong one and later got the right one (according to the dealer), so I hope it's the right one.

I have the rain sensor in an E-klasse and the on in SLK definitely doesn't work. Hopefully it's just a matter of DAS/Star coding as the sensor is present.

 

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and if they installed the right windshield but 'forgot' the 'gel' adhesive then it might not be sticking or in the right position. again, the doors must be closed when testing
 

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i believe u need both. the gel goes on the pad
 

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Discussion Starter · #7 ·
I found info that the rain sensor needs to be enabled every time the battery was disconnected. Is it true? Sounds very strange for me, but it would explain why I have a rain sensor that doesn't work right now.
I'm going to replace injectors in the car next week, so the battery will be disconnected and I don't want to pay for enabling of the rain sensor just to find out that I have to do it again in 2 weeks time.
 

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*Premium Member
2005 SLK55 AMG
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I found info that the rain sensor needs to be enabled every time the battery was disconnected. Is it true?
I've never heard that before, although I'm sure that there must be some other members here who could confirm either way for you...
 
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Founding Member 2006
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I have had my windshields replaced at least 4 times and have never had the rain sensor 'reenabled' by mb or star/das

of course it helps if one has the rain sensor option to start :D
 

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Discussion Starter · #12 ·
/guess mode on/
Maybe if you have the rain sensor as on option originally it's permanently enabled? According to my data card the sensor was not enabled in the factory, so it might need enabling after battery is dosconnected.
/guess mode off/

The part number in mine is A171 820 15 26 (code setting 28), so according to the wisdom of the forum it's a light and rain sensor.
I hope to get access to DAS/Star this Friday.
 

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and a reminder, make sure doors are closed when 'testing' if not in rain :D
 

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2008 SLK55 AMG
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I found info that the rain sensor needs to be enabled every time the battery was disconnected. Is it true? ......
The SLk55 that I own have rain sensors and have disconnected the battery and replaced with a new battery. The rain sensors and AUTO setting works after battery replacement and without coding.
 
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*DAS/STAR Premium Member
2005 SLK55 AMG
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Ditto above ...

Once it's enabled, it *should* stay enabled ...

Something's not right if it needs re-enabling..
 
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Discussion Starter · #16 ·
Update:
Trip to the DAS/star garage, sensor enabled, doesn't work.
Call to a windscreen guy, gel under the sensor replaced (the guy was claiming the gel is enough, no silicone pad required (*) ), doesn't work. Wipers in the first position were working at slow speed, as before activation.
I went home, switched head lights to manual mode in the settings, switch to "Auto", tested light sensor - light sensor works.
Now the interesting thing: wipers in the first position sometimes behave as expected (waiting for rain), but sometimes they work at slow speed. I don't see any pattern yet.
When they "wait for rain" splashing water on the windscreen doesn't activate them. Is the rain sensor broken? Is there a way of testing the sensor electronics (I'm more than OK with soldiering iron and a multimeter)

Do I need to re-calibrate/re-initialise the sensor somehow? There are some comments on ebay [1] about "untrained" device:
"The sensor is equipped with an "untrained" electronic device on production. For this reason, an initialization at the OEM dealer is necessary after installation of the windscreen. Costs for the re-initialization resp. re-calibration are around £30-50 dependent on the dealer.
However, if the "old" sensor is repaired with SensorTack®, a re-calibration is not necessary as the "old" sensor is still calibrated and a correct function is thus ensured.
"

I guess that the thickness of the gel/silicone layer might be important.

[1] Rain Light Sensor Silicone PAD Mercedes Nissan Renault Smart Fiat Citroen H1 | eBay

Edit: I found the pattern: if the wipers switch is set to the first position when the driver side door are open the sensor will "wait for rain". My guess - the sensor is dead :crying:
Edit2: I did some reading and probably I have to wait for a rain to make sure the sensor is dead.
 

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Update:
Trip to the DAS/star garage, sensor enabled, doesn't work.
Call to a windscreen guy, gel under the sensor replaced (the guy was claiming the gel is enough, no silicone pad required (*) ), doesn't work. Wipers in the first position were working at slow speed, as before activation.
I went home, switched head lights to manual mode in the settings, switch to "Auto", tested light sensor - light sensor works.
Now the interesting thing: wipers in the first position sometimes behave as expected (waiting for rain), but sometimes they work at slow speed. I don't see any pattern yet.
When they "wait for rain" splashing water on the windscreen doesn't activate them. Is the rain sensor broken? Is there a way of testing the sensor electronics (I'm more than OK with soldiering iron and a multimeter)

Do I need to re-calibrate/re-initialise the sensor somehow? There are some comments on ebay [1] about "untrained" device:
"The sensor is equipped with an "untrained" electronic device on production. For this reason, an initialization at the OEM dealer is necessary after installation of the windscreen. Costs for the re-initialization resp. re-calibration are around £30-50 dependent on the dealer.
However, if the "old" sensor is repaired with SensorTack®, a re-calibration is not necessary as the "old" sensor is still calibrated and a correct function is thus ensured.
"

I guess that the thickness of the gel/silicone layer might be important.

[1] Rain Light Sensor Silicone PAD Mercedes Nissan Renault Smart Fiat Citroen H1 | eBay

Edit: I found the pattern: if the wipers switch is set to the first position when the driver side door are open the sensor will "wait for rain". My guess - the sensor is dead :crying:
Edit2: I did some reading and probably I have to wait for a rain to make sure the sensor is dead.
If the driver's door is open the wipers will not work so it may seem as though it is waiting for rain but really is only the closed door. If the sensor is functional you can test it by spraying water on the windshield (at the rain sensor) with a garden hose.
 

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my post 13 :D

and a reminder, make sure doors are closed when 'testing' if not in rain
 

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Discussion Starter · #20 ·
I did my tests with open door, no worries! But I also did the tests with closed door and no luck. However I made a step forward: I was watching over the should of the guy when he was enabling the rain sensor and after I came back home I re-checked the procedure. He never did the 2nd step (*). So now when the wiper switch is in the first position nothing happens (door closed, splash on the sensor). Also there is no "first swipe". Previously thee wipers were working in slow mode, so definitely something has changed. I'm going to sleep with that problem and then:
a) buy a new sensor + gel or silicone pad
b) try to find sensor calibration procedure (anyone?)
c) find a new garage with das/star :frown:
c) buy das/star (a bit of overkill..., but I'd enjoy it, no doubt >:D)
d) wait for rain to do a test drive with hope that speed of the car affects the wipers


(*) BODY ---> CGW ---> CONTROL UNIT ADAPTATIONS ---> READ CODING AND CHANGE IF NECESSARY ---> ALL CODES
Change Rain Sensor to PRESENT
 
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