Auto Rain Sensor - Smart enuf for u?

[danc]

Hi everyone,Just sharing another one of my observation and see if anyone noticed the same about the auto rain sensor on the E90. First I asked a service advisor from AB about the sensitivity control on the wiper stalk and can you believe this...he said that it has no effect?? Just meant for wipers with intermittent speed .So even after reading the manual which doesn't tell much I just did my own comparison and here are my obervations.It seems to be based upon amount of rain drops as well as external light. I currently set it at min setting (all the way down) and it seems to work fine and can detect the right speed but once it's dark ie. at night and no street light I need to increase the sensitivity to maintain the 'right' speed for my wipers according to rain fall. Anyone else noticed this?One tip for sure is to keep your windscreen very clean esp at the rain sensor portion of the glass to ensure the rain sensors work properly.Cheers and happy Motoring!

 

[3er]

Rain sensors can never get it right on all makes of cars. Its a quirk you have to get used to for all cars equipped with them.

 

[auxoura]

especially when you set it too lowest and when the screen is full of water also the thing wont move wan....wierd...

 

[pkw88]

especially when you set it too lowest and when the screen is full of water also the thing wont move wan....wierd...

Makes sense. My guess is the rain sensor relies on refraction of ambient light to detect rain drops. In the dark, it would have a marked drop in light, so may not work as well or possibly not at all.

 

[rafamr]

Where is tht sensor normally located? didnt really bother to noticed that eventho i was told that my 95's E34 equip with sensor and occasionally had a weird movement.. or isit the switching problems?

 

[KL2DC]

sensor is right on the windshield behind the rear view mirror....

I have no major qualms with the rain sensor. For heavy downpour you'd definitely have to go manual as the auto wipers never work themselves up to full speed.

Also might help to keep your windshiled clean...

 

[KL2DC]

Makes sense. My guess is the rain sensor relies on refraction of ambient light to detect rain drops. In the dark, it would have a marked drop in light, so may not work as well or possibly not at all.

In actual fact... the sensor is comprised of a sending unit and a receiving unit. Light (infrared?) is sent out into the windshield on an angle, bounces around between in the inside and outside surfaces and is detected by the receiving unit. When the windshield is wet, light escapes due to differing levels of refraction so less light is received by the receiving unit. The less light received, the "wetter" the windshield.

 

[danc]

In actual fact... the sensor is comprised of a sending unit and a receiving unit. Light (infrared?) is sent out into the windshield on an angle, bounces around between in the inside and outside surfaces and is detected by the receiving unit. When the windshield is wet, light escapes due to differing levels of refraction so less light is received by the receiving unit. The less light received, the "wetter" the windshield.

Trust our E90 guru to give us the technical run down on stuff. Keep it comimg KL2DC!

 

[pkw88]

Sometimes I think items like rain sensors are really designed and built on the principle of "Because I can!" That means because I can make it, then I will. Never mind the fact that it isn't particularly necessary, it's the "WOW" factor. I mean, if this rain sensor is so fantastic, why didn't they make it function full time? Why do you have to activate it each time you start the car?

This is technology gone wild!

 

[KL2DC]

factor. I mean, if this rain sensor is so fantastic, why didn't they make it function full time? Why do you have to activate it each time you start the car?

Its a convenience feature, like park distance control. Do you need it? Most likely no, but you wouldn't mind having it.

You can't have it auto on all the time. Think of how many expensive wiper assemblies you'd lose in those drive-through car washes Besides, having choice is a luxury....

 

[3er]

Next, you need a sensitivity control on the rain sensor. (duh).

 

[pkw88]

Its a convenience feature, like park distance control. Do you need it? Most likely no, but you wouldn't mind having it.

You can't have it auto on all the time. Think of how many expensive wiper assemblies you'd lose in those drive-through car washes Besides, having choice is a luxury....

Donnie, I can see how PDC is useful and convenient, not sure about the rain sensor though. I just don't understand how it can be convenient when it doesn't always work.

You're right bout keeping it on all the time. Forgot bout the drive through car washes

 

[danc]

Actually I really like this feature and it seems to work fine for me. I even used it during a torrential rain while driving back Pg-KL so heavy that you can't see the road. Left it on auto it speeded up to max speed to match the rain.

3er there is a sensitivity control.

 

[3er]

3er there is a sensitivity control.

There is? Whereabouts? Is it s a simple screwdriver adjustment or do you need the fancy GT2 and whatevernot to plug in, surf the various menu to find it?

 

[KL2DC]

There is? Whereabouts? Is it s a simple screwdriver adjustment or do you need the fancy GT2 and whatevernot to plug in, surf the various menu to find it?

right on the wiper stalk, there is a roller switch (on the E90), roll down to lessen sensitivity, roll up to increase sensitivity.

 

[KL2DC]

Donnie, I can see how PDC is useful and convenient, not sure about the rain sensor though. I just don't understand how it can be convenient when it doesn't always work.

I must say, again, that I really do not have a problem with mine. I've driven through violent spring showers, humid summer pours and cold autumn rains and the auto wipers do their thing. I like the set-it-and-forget-it effectiveness. Only when its a virtual torrential downpour do I resort to manually shifting the wiper speed to hyperdrive, the auto sensor doesn't do this fast enough.

 

[3er]

right on the wiper stalk, there is a roller switch (on the E90), roll down to lessen sensitivity, roll up to increase sensitivity.

Nice touch. Its not available on MB.