How can I tell if I have a rain sensor?
 

I have a crack in my windshield and it is getting replaced on Thursday (covered under insurance). They asked my if I have a rain sensor. I'm still trying to figure out lots of things on my wagon as I've only had it a month. I'm assuming it does.
Thanks!
Ryan

Do your wipers come on when it rains? From outside the car look at the rear view mirror. Is there a lens siliconed to the glass?

-J

It hasn't rained since I've owned it...only snow. :o Not sure if that makes a difference or not. I'll check the rear view mirror.

The switch would be a clue also--mine is a three position with no adjustment for the intermittent setting since it is self-adjusting with the sensor.

Turn car on and spray with hose and you will see.

A bit hard to do that now since it is -5F out. :o

I did notice that I have no delay on the first position. The first position is the same as the second with the third being fast. But my SD was the same so I guess I didn't know there was an adjustment on Mercedes. Although my wipers don't come on in the car wash so that makes me think I don't have the rain sensor.

On mine...
OFF is off--no matter how much water (i.e. car wash)
I position is self-sensing intermittent--initial wipe, then as needed
II position is low speed constant
III position is high speed constant
Light push-in on end of stalk is single swipe, heavier push-in is washer.

My system has 2 relays--Wiper On/Off and Wiper I/II. Don't know how the electricity works, but IF you have the sensor spot on the windshield but no variable speed, one of the relays may be out. They're about $5-$6 on fast lane, and it's a relay that fits multiple locations.

We're at 2 above here this morning--all the water is solid. Good luck.

would throwing a couple buckets of water Trigger it? (please make sure it's not hot water or another temp that would break glass!)

Ryan, I suspect if you call your local MB dealer with your VIN they can tell you what options are on your vehicle. Or stop by your local MB dealer and have a tech look at your wagon.

Any knowledgeable windshield replacement vendor should recognize and reinstall the rain sensor.

You don't need to throw water on it. The rain sensor is easily visible from the outside. In the center of the windshield about 2-3" down from the trim you can see a purple-blue irridescient spot. That is the rain sensor if you have one. Also if you look on the inside of the windshield in the same spot you will see a small black plastic box which is the cover for the rain sensor.

Correct - test by taking a piece of wax paper and covering it with the switch in the auto position.

That would be the simplest solution now wouldn't it? ;)

I'm positive I have the black box on the inside. But I did not see any "spot" on the outside. I am color-blind and it was not very well lit when I was looking so that may be the issue.

Right now it sounds like I have a rain sensor that is not working properly as when I turn it into position I the wipers run constantly no matter if the windshield is dry or damp.

Take a picture of the box from the outside.

-J

Well, it's more noticeable in brighter light.

If a trip to the dealer is inconvenient, just join EPC-net online (it's free). Put in your VIN at the top and then select 'Data Card' from the Tools Menu (?) and then select SA Code. The Rain Sensor is SA Code 345. If it was installed at the factory it will be listed.

Do the newer cars have all the option codes printed on the front member? Or perhaps on a sticker in the trunk?

-J

Here's how I would do it on that car. In your garage, where the windshield is clean and dry, turn the wiper switch to the first position; the wiper will go once. Then wait, if it doesn't wipe again - you have a rain sensor.

On the w210 (like my 2002 E430) - the rain sensor/automatic mode replaces the 'low' setting on the intermittent stalk (though the switch itself doesn't look any different').

With the switch in the 'low' or 'auto' position, the wiper will still wipe one time (regardless of if there is rain or not) - but it will not wipe again until the sensor detects the rain on the windshield.

Bingo. I looked at it yesterday in the parking lot at work and it was very noticeable. It definitely has the rain sensor.


When I turn it to position I, it wipes continuously regardless if the windshield is dry or wet. Therefore the rain sensor is not working as should.

It may be broken but I wouldn't rush to replace it just yet. Some people have reported that they sometimes act flakey. Try it a couple of times during actually rainy conditions and see how it behaves.

Good luck.

I'm in no rush to replace it. The main reason I wanted to know is because I'm getting my windshield replaced and the operator setting up the appointment told me there were different windshields required for the rain sensor and the cars without the rain sensor.