BMW Rain Sensor Problem

[Quickid]

Did you use Permatex to re-attach the rain sensor?

[dzhoka]

why did not you write what you did.....after all.........can you give us a breaffffffffffffff?!
frriendly

[Weasel]

By the way, the rain sensor RLS module does have an adaptive memory to compensate for a dirts or chipped up windshield, and that adaptation can be reset.

[hongkongloftus]

Yes, I use the Permatex 66BR but my friend said other silicon have same function.

Before I decide to do the DIY, my rain sensor has mal-function for a long time and I only have auto headlight functionally. So I think if I screw up the sensor system, I only loss my auto-light and it is not a big deal. If you same as me, try to start the work.

1. Take out the cover of the rain sensor (RS) behind the mirror. Unplug the cable of the sensor module. Push down two hooks on the both side of RS and take out the RS module. DON’T touch any inside surface of the RS. (This is the easier step.)

2. Now you can see a plastic bracket with some sensor eyes attached onto the windshield. Use a marker or tape or any method to mark the position of the bracket (I forgot to do this and then I can’t re-install the cover of the sensor)

3. Use a thin & sharp knife or cutter to cut the existing silicon in between the bracket and the windshield. Try to cut in surrounding method until you can twist the bracket with a little space. Then CUT & then TWIST…… If you can turn around the bracket, you become successful to move out the bracket. This is the most difficult and danger step, be patience and be careful. DON’T damage the surface of the bracket and windshield especially the coating onto the windshield. DON’T use the front sharp point to cut the silicon, use the knife body to slide into the gap between bracket and windshield. BE CAREFUL your finger and hand when you use the knife or cutter. Carry on turn around the bracket until it can move out.

4. After move out the bracket, use your finger to push out all the old silicon on the bracket and windshield. DON’T use any tools because it can damage the surfaces. You can use the industrial alcohol (85%) to clean up all the remaining silicon. DON’T clean up the marker on step 2.

5. Read the instruction of the 66BR firstly. Apply one or two horizontal rows 66BR on the middle of the bracket and don’t apply too much to the both ends. Use a flat plastic sheet (I use a cake sheet) to make the 66BR smooth and even and flat for cover the sensor eyes locations. To stick the bracket to the windshield onto the original position and apply a little pressure to let the bracket evenly. Let other person to observe the sticking condition outside the windshield to avoid the air bubble. Add more pressure to release the air bubble. Then DON’T MOVE and DON’T SLIDE for few seconds (maybe 10 or 15 sec.). Leave the bracket and re-confirm the right position. (This step is the most critical.)

6. Open the roof and front door to let the good ventilation for an hour. After that, you can use your car but don’t touch the bracket within two days.

7. Two days later, see the result of the bracket attached outside the windshield. If there have no air bubble and the silicon look even, you can re-install back the RS and cable. Otherwise re-do again and apply more 66BR. Test all function of the rain sensor and auto-light.

P.S. Un-plug and plug the cable, don’t insert the key.

[hongkongloftus]

After all function tested, I put my car outside under sunshine for 12 hours to test the 66BR. That's no problem.

Finally, my results are:
A: Cannot put back the cover onto the right and fit position because I forgot to mark down the original position of the sensor, then I need to use a tape to fix.
B: Auto light function have seen some delay btu still function, maybe I applied too much 66BR. Try to apply thinny.
C: Rain sensor is function but I need to activate once time on raining to start the function. Then it can stop when no rain and it can start when rain again. The intermediate step can function now, also it can stop when the car stop to move.

[patrickkc]

resurrecting an old thread. Same thing is happening to my x5 as well. My head lights will sometimes turn on in the dark when set to auto but sometimes they won't come on at all. My rain sensor wipers are not working at all so I'd assume this is the problem. I have 2 small bubbles when I look at the sensor from the outside.

Reading this thread, I would assume I don't need a new sensor module but just need to take out the IR receptor and re-apply it onto my windshield without any bubbles?

@weasel- How do I reset the adaptive memory? maybe I should give this a try first before trying to reposition my IR receptors onto my windshield.