BMW Rain Sensor Problem

[bbbngai]

[FONT='Verdana','sans-serif']I bought my 2nd hand X5 (2004) in Hong Kong a couple of months ago. Everything seems fine except the rain sensor. It does not work even when it is raining dogs and cats. I cannot even choose any intermittent speed (at least I want to have a slow wipe - just like the old version BMW w/o rain sensor). I have searched all the webs and now become an expert.

There are basically 3 ways to deal with the problem:-

(1) Replace the OEM windshield with the original IR receptor attached. This ensures the sensor receives a clear and accurate signal and it will save all the problems. If necessary, you may also need to replace a rain/light sensor unit (just between the IR receptor and the mirror), which is a easy DIY job.

(2) If you have already replaced a windshield which is not OEM, you may find bubbles in the IR receptor area. This cause the rain/light sensor malfunction. You have to remove all the adhesives on the surface of windshield and the IR receptor (be careful not to break the IR receptor when you try to take it off). One way to attach it to the windshield is using a thin layer of transparent (not translucent) silicon gel. Someone has tried the 'Permatex 66B' and it works perfectly well and no need to change another OEM windshield.

(3) Just unplug the rain/light sensor and you will get the intermittent speed back (just like the old model, i.e. it will speed up when you are driving and slow down when the car is station...wow!) Unfortunately, you will also lose the auto light (that I don't really care).

Mine is an OEM windshield but somehow, the air bubble appears and cause all the problems. To me, the rain/light sensor is cool but if it creates problem...further problems, I'd rather sacrifice it. That's why I choose option (3) and I am still happy with this choice. Maybe one day when my windshield is cracked and it is insured, I will get it again. Ha Ha.

Thanks for your attention.
p.s. if you want to see DIY photos, please let me know.[/FONT]

[carlgo]

I really like my auto wiper system, much more than I thought I would, and would hate to lose it.

This has to be asked: did you activate it properly? I'm sure you did, just asking.

I don't buy the bubble thing. I have looked through thousands of windshields and I have never seen fields of bubbles. And it is hard to believe they would appear just in that small sensor area.

Also, the system requires a fair amount of mist and rain drops to turn on. This would be equivalent to a huge number of really nasty defects in the glass. And if there were a field of bubbles, the wipers would be on all the time, thinking it was raining.

I think it is either activation problems or a defective sensor. Or maybe whatever module controls all this. I am sure there is a fairly simple electronic test to find out what the problem is.

Lastly, on many vehicles with sensors or other fancy options, OEM glass is used for replacements. Sometimes owners are adamant about getting that little BMW etching back. So, that insignia is not proof that the WS has not been replaced.

Glass shops, especially the insurance-friendly cheapo ones, are notorious for breaking wires, using the incorrect adhesives and all that.

So, back to the testing idea. At least you would know what the problem is.

[dzhoka]

If windshield is not OEM sensor is fail or sometime , like it was in my situation , did not work at all. After installation of original BMW glass rain sensor workin just fine till present time ( about 2 years since ).
Now if your winshield is original , first try to take ( borrow from other guy ,who has the same model x5) a new sensor ( 200 usd usually) replacement is fearly easy and you can do it yourself. Be caryfull with plastick hooks on windshield ,when reattach sensor itself, by not braking them .
If that does not help ,-you need to replace a stearing wheel column regulator. Step by step. Good Luck
please revieu when you'll finish succesfully

[msammy]

My rain sensor worked like crap and mostly not at all. I found that the sheeting action on the windshield was the problem, meaning the rain was just running down the glass with no beading at all. I fixed my problem by applying a coat of Rain-X on the glass to get the beading action of the rain again, and it worked! Cheap fix - try it before messing with the sensor and/or windshield!

[bbbngai]

After several years, the moisture will cause gap between the windshield and the IR receptor and the field of bubbles will become bigger and bigger until the sensor malfunction. I try to post a picture here to show you how the sensor works. In fact, the rain drop on the sensor area causes refraction that diverts all the IR away. The bubble in this area block the refraction and therefore the receptor always receive signal (IR) and assumes no rain at all. The reason why I do not want to change the windshield because it may damage my car (have you ever seen how the technician replaces a windshield - it is so appalling!). Unless there is a crack on my windshield.

[rogerkiu]

Originally Posted by bbbngai

[FONT='Verdana','sans-serif']I bought my 2nd hand X5 (2004) in Hong Kong a couple of months ago. Everything seems fine except the rain sensor. It does not work even when it is raining dogs and cats. I cannot even choose any intermittent speed (at least I want to have a slow wipe - just like the old version BMW w/o rain sensor). I have searched all the webs and now become an expert.

There are basically 3 ways to deal with the problem:-

(1) Replace the OEM windshield with the original IR receptor attached. This ensures the sensor receives a clear and accurate signal and it will save all the problems. If necessary, you may also need to replace a rain/light sensor unit (just between the IR receptor and the mirror), which is a easy DIY job.

(2) If you have already replaced a windshield which is not OEM, you may find bubbles in the IR receptor area. This cause the rain/light sensor malfunction. You have to remove all the adhesives on the surface of windshield and the IR receptor (be careful not to break the IR receptor when you try to take it off). One way to attach it to the windshield is using a thin layer of transparent (not translucent) silicon gel. Someone has tried the 'Permatex 66B' and it works perfectly well and no need to change another OEM windshield.

(3) Just unplug the rain/light sensor and you will get the intermittent speed back (just like the old model, i.e. it will speed up when you are driving and slow down when the car is station...wow!) Unfortunately, you will also lose the auto light (that I don't really care).

Mine is an OEM windshield but somehow, the air bubble appears and cause all the problems. To me, the rain/light sensor is cool but if it creates problem...further problems, I'd rather sacrifice it. That's why I choose option (3) and I am still happy with this choice. Maybe one day when my windshield is cracked and it is insured, I will get it again. Ha Ha.

Thanks for your attention.
p.s. if you want to see DIY photos, please let me know.[/FONT]

I had this problem before, it was definitly the air bubble. I went to a local automible glass shop in Hong Kong and replaced it with OEM windshield, it then works fine till now. The rain sensor had no problem at all. Don't worry about the cost for windshield replacement. If your insurance is comprehensive insurance, then you can raise your claim for accident damage of windshield. Otherwise, it is just HK$4500 (around US$550). If you want more infomation, email me at [email protected].

[bbbngai]

Hi Roger, thanks for your advise. I am comprehensively insured so I will give it a try later.

[hongkongloftus]

Hi bbbngai

Thank you for your post. Same problem in HK since 2006. I have an interest for your point 2, pleae let me know details and where can I found the materials gels?


Hi Roger

On the insurance issue, I understand we can claim the whole OEM windshield, but we only can claim when the windshield really damage and need to report to police, it is right? In my insurance policy, insurance company only allow us to replace the windshield on their nominated company and they charge around 6.8K. Any comment???

[rogerkiu]

Yes, you are correct. The insurance company only replaces your windshield for accidental damage. However, you can just break the windshield by yourself and report to your insurance company that the windshield is broken by a small stone when you are driving on somewhere like Eastern Corridor of HK Island. You do not need to report to police, just report to your insurance company. Actually the repair company will teach you how to raise the claim to your insurance company. Generally, the insurance covers HK$8,000 for replacing the windshield per year, so 6.8K is no problem.

[hongkongloftus]

So happy.

I fixed the rain sensor now.