I'm just in the process of going through the same issue following a windscreen change last week. It was done by my insurers appointed team and they fitted the wrong screen (the light sensor prism module is a different shape), and damaged the prism bonded to the screen. The fitters actually cheese wired the sensor prism off the old and new screens and tried to swap them over. The result is that the sensor window is now opaque and the lights are on all the time and the rain sensor wipers don't work.

I'm now having the windscreen replaced with a BMW original screen by my dealer at the insurers expense tomorrow.

The important bit to note is that the sensor prism MUST have an optically pure/clear connection to the glass. The rain sensor bouces infra-red light through the glass and measures the reflected (or is it refracted) light at the other end. Rasin on the glass changes this and the difference causes the auto wipers to work at an appropriate speed. If the connection between the sensor, prism and glass is anything other than perfect the system simply doesn't work.

You will probably be better to go back to the company that changed your screen and get them to replace the screen and any other borken parts at their expense, or take it to BMW and get them to replace it, again at the glass repairers cost.

Hope this helps.

rain sensor ( part 2)
 

Yes it is true rain senson also regulating auto lamp funcion.
Is there any mashurment of this perfect distance between this sensor and glass itself ? Logically ..this broken plastis holders was calibrating perfect distance...and now they are not exist ( one -right side only )
The epoxy will help me to rise the left side level ..and likely will make even serfices ( By the way I wrote that sensor itself is alive !)..I am shure epoxy will hold properly the weight of the sensor..But I have no idea at this moment how to estimate this perfect distance... Does anybody did such manipulation- meshurment before ?? On practical field ?
I am very sorry for untipical terms and corruptive language , - english is my third one! I am doing my best !
Preveouse article was helpfull in the way ..I do appriciate one !I can not go back to the shop where it was brocken ets...And sertain terms of insurence is not covering that situation ..
regards John! ( the batle is not over yet !!) :rolleyes:

Why can't you go back to the shop where it was broken??

I'm not sure exactly what you are trying to fix, its difficult to help without pictures.
If your trying to get the sensor to stay in place as the clip is broken, have you considered trying double sided sticky pads.
You can get these in various thickness. It may be worth experimenting with these before trying a permanent glue fix.

If it is the prism unit that fits flush against the glass, there is no way of fixing it. It requires a special bonding process that you will not be able to replicate, and the result will be no good.

I've just had my screen replaced (£706 inc fitting - salient point for all those without glass insurance (I do have it)) and talking to the BMW mechanic he told me that even they can't replicate it at the dealership, only the windscreen manufacturer can fix that.

If it's the electronics that clip onto the bonded prism then you may be able to get them to fit, but it won't be easy (pictures of the problem would be a real help here), and the whole auto wiper/auto lights system then needs re-initialising by the dealer. This again was something the original windscreen repairer could not do. It doesn't take long (about 15 minutes), but it still has to be done in order for everything to work again.

Hope this helps

there is rain in SF like cat and dog , I did not do any pictures yet . Promis to come back with results and photous
regards Johnni 25 dec 05
Marry Christmass to all !

Johnni:
I had a problem with my rain sensor and auto lights a few months ago after my windshield was replaced. The work was done at the dealer and required an hour and a computer to make the required adjustments. You might want to at least contact the dealer and ask them what the procedure is for solving your problem. Perhaps someone here can can then direct you regarding weather it's a problem you can solve on your own. Wish you the best.

Dear Barry ! Thank you for answer ! I know a little bit myself too and will shere with you as well. This sensor is standing independetly from main chip on board ( x-5.4,4...2003, sport pac) So it's needs no PC regul. or programing. Because mounted plastic holders on the serface of the windshild ( inside car , behind rear view mirror ) desined with pressision to hold this sensor, it does not need any other work ,but instalation and connectivity only.
Mine 2 of the 4 plastic holders are broken so..Only them created this disscusion
regards Johnni
dec26.05, :rolleyes:

to finish this story nicelly
 

I did a lot of thing to fix it...with a glue and without...( without diller advice !!!) and sugestions from all over the world where my friends lives..!
I came to conclusion ...--winshield must be replased..and original BMW suppouse to be placed..There is no other chance to fix it ! Thank you all for participating ur attension and replyes. I trully injoying this site and will be posting my best knowlege as well.
Arrivederchi Johnni
jan13,06

The "Arrivederchi" explained alot - I have complete sympathy for anyone trying to learn English(American) as a second language - I learned more about 'my' language taking German (Deutsch) than I did in English class - American is so confusing, even to Americans!