Rain sensor : strange behaviour
 

Hi folks,

Yesterday I had to take a long trip in the rain and I noticed that my rain sensor acts strange, to say the least. I was raining very light, so initialy the wipers went on for about every 6 or 7 seconds. Perfect for me. But then, after a couple of minutes, they started wiping constantly, even in the same rain conditions. Only when passing through a tunnel, they stopped. The sound of hearing the wipers going over a dry window is pretty frustrating.

When I turn off and on the sensor system again, it all works fine, but again, a few minutes later, it starts again ...

Any of you have/had the same experience ?

Thanks!

I find the rain sensor regardless of the sensitivity setting is far too sensitive.. it also seems to be somewhat speed dependant... I don't use auto as a result...

Maybe that is the reason yes, far too sensitive. I wonder if this is programmable...

speed sensitive - perhaps you were going faster at those times? I've got my dial setting to lowest most times because it can get to be too much - so when it does rain harder, I have to adjust it upward sometimes... not as automatic as I'd like.

Yes, I'm rather disappointed in the rain sensing wipers. The rain sensing wipers on my 2004 Z4 are perfect... it seems to always wipe at just the right time and I never have to adjust it. I was looking forward to the feature on the new X5, but I find it much inferior to the Z4 for some reason, i.e., not much more convenient than normal manually adjustable interval wipers.

Question:

Is the sensor beneath the rear-view mirror smart enough to
1) Feel the drops so it's knows it's raining only
2) Counts the number droplets on the sensor per time interval so it knows how hard it is raining thus adjusting the wiper speed

If number 2 is true, then why the hell do we need to speed adjustment dial on the stalk?

My old e39 didn't have the fancy sensor, but it was smart enough that when I sit at a stop light, the wiper speed would reduce from slow to intermittent so it's not wiping constantly.

It's not a speed adjustment, it's a sensitivity adjustment. A subtle, but significant, difference. Some people prefer fewer "wipes," even though it means more rain on the windshield between wipes, while other prefer a cleaner windshield, even if it means more frequent wipes.

A speed adjustment would simply alter the interval between wipes on a time interval basis, independent of how much rain is falling. A sensitivity adjustment essentially alters the amount of rain between wipes, and therefore should speed up and slow down as it rains more and less.

I was impressed with the rain sensor during yesterday's first snow. When I left the office last night, I stopped at the driveway, and a bunch of wet snow slid down to the windshield. When the wipers encountered this, they went into rapid mode for a few swipes to get rid of the snow, then went back to slow mode. This happened a couple of times getting home. Pretty impressive.

Great to see they work well with snow.. it never snows in Sydney :nanana: Btw I have some nice curved scratches on my windscreen from what would appear to be some abrasive substance on the wiper rubber and the auto wiper wiping when the screen was too dry... as I said I don't use.... my wifes mercedes sensor is perfect...

i also find it very annoying compared to my e53...

sometimes its too frequent, sometimes you just wish that it would wipe more...

lol...

Generally it works good in my car, better than some on past MB cars I've had. The ability to adjust the sensitivity is a great feature, and something that Mercedes is sorely lacking.

I usually find it wiping too much when it is misting and you are following cars. Even at the least sensitive, the thing was going like crazy. Yet, sometimes, I'm sitting waiting for it to wipe.

Wish the sensitivity was more than the 4 or so clicks you get... a dial with "infinite" adjustment like you get in cars with variable intermittents would be great....

Thanks for all the answers, seems like I am not the only one with this issue. Also talked to BMW Tech guy yesterday and he says the sensitivity of the rain sensor can be programmed via the 'Car Key Memory' function at the dealer.

Will try this the next time I am at the dealer...

mine too
 

I have noticed the rain sensor goofiness on my 2010 X5 diesel. My 2009 M3's sensor works exactly as expected (i.e., the same as the sensor in every BMW I've owned). The M3 is assembled in Germany while the X5 is assembled in the U.S., of course. Perhaps the mirror/sensor assembly supplier is different and the U.S. version doesn't work as well. Just a thought....

I've noticed same poor performance of rain sensor in 2009 X 35d. Not functioning nearly as well as previous BMW, 2002 530i.

Have noted issue of wipers taking off and wiping too fast, and sometimes not wiping enough.

I've had this happen a couple of times. I find doing a quick wipe - pushing the stalk down cures the problem.