Rain sensor sensitivity
 

The automatic wiper rain senror... It says in the manual that the sensitivity can be adjusted by the dial. Should that actually do something? I would imagine if you adjust it to less sensitive the glass would get more wet before it wipes. If you adjust it to more sensitive it would try to keep the glass cleaner.

No matter what setting I use, it keeps wiping exactly the same. To me the rain seemed rather 'constant' and was quite light. And the wipers wiped almost dry glass way too often.

Any experiences?

- p

hmm ... its been raining here all day & my wipers were set on low & seemed to adjust well to the rain .... they wiped faster when it rained harder - then slowed again when the rain did ...

Yep it does that. However, I would imagine the sensitivity would adjust how much the rain amount needs to change in order for the wiper frequency / speed to change. Or something like that...

for me the sensitivity changes how sensitive the sensor is to minute drops of rain. Not even rain, but water lifted from the road. On the highest click the sensor will keep wiping with water from the road that is lifted from other cars.

With it down lower it won't. On all three of our cars its always worked perfectly.

Maybe you have bubbles in your sensor? This was a common problem when BMW first started fitting the sensors to cars...

I was expecting something like that. I could not tell the difference between those 5 settings.

Thanks, p

I have also wondered this issue couple of times. It seems that sometimes when it drips, I have tried to find more sensitive level for the sensor when its already at the max..

Let's not forget that it is a sensor and as such, water droplets must be in front of the sensor in order for it to send a command to wipe.

There is never a perfect distribution of rain drops on the windshield so there could be times when there's more water in your view than on the sensor itself.

If only there was a rear window rain sensor...

Oooooh. Doesn't seem like it'd be that hard to mod, does it? (I know, famous last words, right?!) Wonder if a relay could be installed, wiring the sensor cue to the front wipers back to the rear wiper... The detail to handle would be what if sensors are active and the rear wiper is activated by hand, the relay would have to be able to switch over to manual without causing any probs in the circuits. I'm up to my ears in other mods right now, but that seems like an interesting one, too! Anyone want to give it a shot?

In terms of the front wipers, I agree it's just the nature of a sensor. Making it too sensistive would be even more annoying. Mine are adequate at any given time, with the sole exception of light misting that obscures the windshield but doesn't trigger. Within 1 or 2 secs of thinking about manually upping the wipers, the sensor kicks in. No complaints here.

and while were at have an ambient light sensor for the navigation. So when it's dark, the nav is dimmer. When it's light, nav is brighter.

I hear ya! I wish it existed.......doesnt sound like a difficult thing for BMW to make.

If the lowest setting is still too sensitive, you can probably get sensitivity adjusted at the dealer (?)

I know that in light snow the sensor tends to overreact, but it seems okay in rain.

Talking about snow... When it is below freezing and snowing quite often there actually should be no requirement to wipe at all. The key thing is to _not_ have warm air blowing to your windshield and the snow would never hit the glass due to air moving it away while driving. And if the glass is cold and you stop, the snow will blow away automatically again when you start to move.

I think I am just personally used to not keeping the glass ultra clean (and wiping almost a dry window all the time) and found the automatic sensor too sensitive even with the lowest setting.

I also would not want a rear glass sensor since the water you get on the rear glass is always dirty. If it is raining hard, the sensor might work fine from dirt perspective. But if the road is just wet or raining a little, the wiper would wipe the glass with quite a bit of dirt on it and the glass might end up with scratches and premature wear. I prefer using the rear manually with enough water every time.

That is also the reason why I don't like an automated rear wiper activation when reverse gear is activated and front wipers are active. You might wipe a glass with an inch of dirt on it without any water (I hope my BMW does not have this functionality).

But maybe that's just me.

- p

I'm going to have to disagree with the scratching part. The "dirt" on the rear window is typically a thin film not coarse enough to cause hazing or scratching unless it has dried up on the window. The water suspended in the dirt will prevent it from causing any harm. If it were that easy to scracth or haze, then we should not be using front windshield wipers.

As for the rear rain sensor, it could be engaged manually just like the front ones. If you prefer to manually wipe, then don't engage it. As my X is today, I hate leaving it in rear wipe intermittent mode because I don't want the premature wear on the wiper. What I end up doing is engaging a manual wipe once the rear window is obstructed with rain drops or dirty film.

My two pennies.

I feel the lowest setting is still not low enough for me.

We don’t like this feature and had it turned off, couldn’t stand that scraping noise on an almost dry windshield!

BMW has OVER engineered this feature
Anybody remember the good old days (early 90’s)? Set the delay to a nice slow wipe and forget it until you stopped at a stop light that’s when that wonderful BMW would stop the wipers or set them to a really slow delay. O WELL I guess this over kill justifies over 40K $’s for a 30K car.
:rofl:

If you think a simple rain sensor is overkill, how about a 7 series guys? The driver's wiper is constantly regulated for "optimum sweep", the wipers park in a fractionally different spot each time, etc etc etc. (see bmw site for more details lol)

I personally really like the rain sensor, but then again I'm kinda lazy.......

I hate the rain sensor in the X3 its so damn complicated whereas in our ML just activate it and it works fine without any adjustments. Its only after 3weeks i figured it out in the X3 and now its all good...

Hi everyone,
I have a slightly different problem I think on my X3 if I set the wipers to rain sensor mode it won't come on again after I have removed the keys gone shopping etc I have to retrigger the auto sensor again via the stalk or sensitivity dial to get it working again have i messed up the program somehow? or am i not putting it into sensor mode correctly?? works fine when its triggered and we are driving along
Maxey Australia
Any ideas welcome

Thats how it normally works. This is to prevent the sensor from harming the wipers, say for example if the car was about to enter an automated carwash. Most automated carwashes require cars to turn be dropped off and the engine switched off before being moved to the belt and carwash. The fact that the car is shut off and on provides an extra security precaution.

Another example could be snow. Heavy snow could have collected on the wipers, but not the sensor. Upon starting the car, the sensor might detect the snow falling and attempt to activate the wipers, before the driver has realized that the snow needs to be brushed off...

Just two examples off the top of my head. The system is designed to prevent accidents and unnecessary repairs...

Rain sensor operations
 

Thanks for that --quite logical when you put into your context
Maxey:)

Anything I can do to help :)

Reviving an old post. My '07 has the same problem as the original poster's. It's too sensitive and adjusting sensitivity makes no difference. I'd rather just disable it. Does anyone know how that's done? Can I disconnect the wires to the sensor on the windshield? Thanks.

Have you had a windshield replaced? Your symptoms are often related to a sensor that is not properly bonded to the glass.

I bought the car used so I don't know about the windshields history. I guess I'll remove the cover on the sensor and check to see if it looks well bonded. Do you know if it will be obvious if there's a problem? Is rebonding something I can do on my own? Thanks.

look at the seals stamped on the window - if there is a BMW roundel, the windshield is OE, and while it may have issues, it is done to the factory specs. If there is no BMW roundel, it could have been an aftermarket one... Companies that make glass for BMW are Sekurit, PPG and Saint Goblin (or goben??)... As a matter of fact, you may have different glass manufacturer on the same car, right from the factory - all of them will bear the roundel stamp...

according to the BMW documents, the bonding process is factory only and can not be replicated outside of the factory - i would take that with a grain of salt, i am sure if you do a serch on this forum, you will find something on the contrary...

You can try regluing it, but the standard approach is to replace the windshield. Any bubbles between the glass and the sensor affect the sensitivity.

After replacing the windscreen or fitting a replacement sensor it is necessary to calibrate the sensor to the glass, which can be done with INPA.