rain senor..how does it work
MBWorld Fanatic!
Joined: Nov 2001
Posts: 6,340
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From: Southern California, USA
2003 CL55 AMG
The rain sensor does work really well. It basically uses a Infrared sensor in the window located behind the rear view mirror to measure how much percipitation is on the window. From this measurment it knows what speed to set the wipers at.
Super Member
Joined: Nov 2001
Posts: 570
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From: Agoura Hills, CA
C230K
the sensor scans a small area, where the sensor is located. basically when the signal it sends out is scattered, or interferred or something along those lines, it relays a signal to wipe the windshield. since rain is distributed pretty evenly across your windshield the small area scanned is a good approximation of the entire windshield.
i hope this makes sense. or else i can go mathematical and explain it using statistics and all that nonsense (ie standard distribution and sample populations to model the entire population - rain in our case)
i hope this makes sense. or else i can go mathematical and explain it using statistics and all that nonsense (ie standard distribution and sample populations to model the entire population - rain in our case)
Member
Joined: Nov 2001
Posts: 144
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From: Midwest
2002 C240
I believe the rain sensor sends out infrared beams across the winshield and measures how much is reflected back. The amount of rain drops on the winshield will refract the beams and affect how much of the beam is reflected back thus adjusting the wipers accordingly.
Now if the winshield has to be replaced...does the rain sensor have to go along with it? It'll be an awfully expensive winshield replacement if that's the case.
Now if the winshield has to be replaced...does the rain sensor have to go along with it? It'll be an awfully expensive winshield replacement if that's the case.
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Joined: Nov 2001
Posts: 1,148
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From: Berkshire, UK
2004 SL55, 2015 A250d, 2016 GLC250d
The rain sensor (as Adam says) is behind the mirror on the windscreen. If you look (from the outside) at the sunshine band at the top of the windscreen, in the top middle, you can see a 1" by 1.5" purple(ish) colour square where the sensor is.
The windscreens for rain-sensor cars have a metal clip bonded to the windscreen when the rain sensor is clipped onto.
Technically the sensor needs recalibrating (from Star diagnosis system) after the windscreen is changed, although that wasnt done when my windscreen was replaced and it still works fine. I suspect if you change the tint color then it needs re-calibrating.
Rain-sensors are great. and work really well. Occasionally they get confused if driving through heavy trees where you get glints of sunshine coming through. I wouldnt but a MB without one. A problem in my wife's ML was that if you drove thru a big puddle that soaked the windscreen you couldnt see thru until you got the wipers on. The rain-sensor just deals with that and keeps you able to see the road. (in fact we just changed the ML to one with a rain-sensor)
The windscreens for rain-sensor cars have a metal clip bonded to the windscreen when the rain sensor is clipped onto.
Technically the sensor needs recalibrating (from Star diagnosis system) after the windscreen is changed, although that wasnt done when my windscreen was replaced and it still works fine. I suspect if you change the tint color then it needs re-calibrating.
Rain-sensors are great. and work really well. Occasionally they get confused if driving through heavy trees where you get glints of sunshine coming through. I wouldnt but a MB without one. A problem in my wife's ML was that if you drove thru a big puddle that soaked the windscreen you couldnt see thru until you got the wipers on. The rain-sensor just deals with that and keeps you able to see the road. (in fact we just changed the ML to one with a rain-sensor)
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Joined: Jan 2002
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2002 C240
It's the best
If there is one thing I LOVE about my mbz, it is the fact that the rain sensor works incredibly well. It's such a joy to drive and not have to fumble with the wipers especially in a wet climate like the NW.
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MBWorld Fanatic!
Joined: Nov 2001
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From: Gaithersburg, MD
2002 C240 6-spd (ret)
Yep, it's one of those great conveniences that once you have it you can never go back. The original intermittent feature most everyone has now was good, but I was always adjusting the delay frequency. Now I just sit back and let the sensor do the work. Also, now I'm actually glad there's no sensitivity adjustment like there is on some other sensor setups. The setting on mine is perfect.
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Joined: Nov 2001
Posts: 3,600
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From: Earth
GLB 250 4matic
i have to say that when i test drove the car, and the salesperson told me about the rainsensor, i thought, 'what a gimmick?' and it was raining! i wasn't even going to get it but it came w/ the moonroof package.
but since then, i've grown to really like it. the only time i don't like it is when it does the dry wipe when i forget to turn it off and then start the car again.
but since then, i've grown to really like it. the only time i don't like it is when it does the dry wipe when i forget to turn it off and then start the car again.
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From: Downtown Columbus
w211 e500
Super Member
Joined: Feb 2007
Posts: 857
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From: Downtown Columbus
w211 e500
I actually use that to my advantage, like when its snowing, and I'm about to clean off the car in the morning, i turn the rain sensor on, then get out the car and shut the door then the wipers swipe, vs them coming on with the door open and push snow into my car. Weird the little things we use. lol.
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Joined: Jan 2005
Posts: 2,848
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From: Orange County
2005 C Wagon (No snickering please!)
A recent California law requires drivers to operate their headlights anytime they operate the wipers. Technically, you could get a ticket if the wipers operated when the sun was out.
Mercedes knows of this law, and could program the cars to turn on the headlights automatically, but they have not acted.
Newbie
Joined: Jan 2008
Posts: 4
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From: Sacramento, CA
2005 C230 Sport Sedan
I'm in CA, and I can say that my headlights automatically turn on once my intermittent setting is constant. So they won't turn on if its just doing a wipe... then delay, then wipe.... but once it switches to wipe, wipe, wipe they'll switch on. Hopefully someone else from CA can confirm that and I'm just not crazy :-) 
MBWorld Fanatic!
Joined: Feb 2004
Posts: 3,124
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From: Milton/Westport, MA USA
me: 2015 SL400 & 2015 ML400; wife: 2022 GLC Coupe; daughter: 2017 GLC SUV
A recent California law requires drivers to operate their headlights anytime they operate the wipers. Technically, you could get a ticket if the wipers operated when the sun was out.
Mercedes knows of this law, and could program the cars to turn on the headlights automatically, but they have not acted.
Mercedes knows of this law, and could program the cars to turn on the headlights automatically, but they have not acted.
