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Auto wipers (rain sensitive) not working

Syncros Mar 8, 2020

  1. Syncros

    Syncros Reactive Member

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    I'm struggling to find any information or similar experiences to this anywhere.

    I have a pfl S3 8V Sportback, since having it the rain sensitive auto wipers haven't worked, I can disable the 'rain sensitive' function from within the mmi which swaps them over to basic intermittent (which works fine) but changing back to 'rain sensitive' and adjusting the stalk to the correct position will wipe the windscreen once but that it. The windscreen has been replaced at some point so I'm wondering whether the sensors dead, wiggling the cable attached to the sensor will trigger a single wipe. No matter what I set the sensitivity to it's the same deal, has anyone seen this before and any advice for what to be looking at or what to check?
     
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  3. JohnM100

    JohnM100 Registered User Gold Supporter VCDS Map User

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    Assuming your car had rain sensitive auto wipers from the factory (or was retrofitted properly) it does sound like a problem with the rain sensor wiring or gel pack

    Less likely but possible is a problem with the sensitivity selector on the steering wheel stalk.

    Gel pack is probably the easiest thing to look at and change. IIRC it’s one nut to loosen and swivel the mirror housing 90 degrees to access.
     
  4. Syncros

    Syncros Reactive Member

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    Is there anyway to test the sensor is working as it should be (without replacing the whole unit and gel pack). I suppose I could attack it with a multimeter
     
  5. JohnM100

    JohnM100 Registered User Gold Supporter VCDS Map User

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    Short answer is I don’t know but it’s good practice to replace the gel pack when changing the windscreen. Some people on here have been successful just asking any autoglass man they see for a gel pack as they are basically a minimal cost consumable part.

    A qualitative test is to spray water from a pump dispenser onto the outside of the screen but the 8V uses different calculations for stationary vs moving vehicle so that is of limited value in real terms.

    You state you have the wiper option in MMI so the car should know it’s there but can also try a person on this forum to do a VCDS scan to see if any errors pop up. You can find the nearest to you in the VCDS map section on here - can’t link to it as am on Tapatalk but should be accessible from the main homepage.
     
    Last edited: Mar 8, 2020
  6. Syncros

    Syncros Reactive Member

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    I'm unsure whether the gel pack was changed with the windscreen (as it was replaced before I owned the car and I haven't seen any paperwork) although from the exterior, the gel pack itself does look okay, there are no air bubbles and I can see the sensors. Even if there was a problem with the gel pack I'd still expect the wipers to be moving, if only erratically but it's almost as if there's no data being sent by the sensor.

    I've ran numerous tests in the bad weather we've had recently, while the stalk is at position 1 the only way to get the wipers to move is by either adjusting the sensitivity or moving back to position 0 and then back to position 1, either of those two options will swipe the wipers once but after that they're lifeless again.

    I do and it's when enabling 'rain sensors' that position 1 is essentially a dead position, that's why i'm wondering whether it's the sensors itself that's bad. You're right, it might be worth seeing if I can go down the VCDS route.
     
  7. jiannu

    jiannu Member It's my birthday

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    Did you check on your mmi menu to see if its checked "rain sensor" on?

    Sent from my SM-N975U1 using Tapatalk
     
  8. Peto

    Peto Registered User

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    I turned off rains sensor it completely wiping screen improperly...Best to control it manually
     
  9. jiannu

    jiannu Member It's my birthday

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    Was your winshield ever replaced? Mine worked flawlessly until I had to replace the windshield.....as the installer went with a cheap aftermarket one.

    Sent from my SM-N975U1 using Tapatalk
     
  10. Peto

    Peto Registered User

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    Exactly .. when I bought car they said only bumper and wing was replaced but then I spotted different brand on windshield so was replaced too and they even glued it badly as I could hear wind on left side when I was driving lik e90 -100 So I bought sticking rubber strip and sticked it on sides and top and it is perfect now.. https://www.aliexpress.com/item/32984987992.html?spm=a2g0s.9042311.0.0.27424c4dSX0UVH
    But sensor is ok it initiate wipers but they have interval according water drops which I hate. Then u can't use it and mix it normal wiping lever in first position as it has selective intervals 4 positions and I constantly changing them depending of the rain but even if screen is dirty I just can't stand dirty I use water so much :D
     
    Last edited: Mar 9, 2020
  11. Syncros

    Syncros Reactive Member

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    Yes, it has (at some point) been replaced.

    In honestly, it's not a massive problem (as I can just use intermittent for now) so I'm not placing any particular urgency behind fixing it, I was just throwing it out there to see whether anyone had seen this before. It's in for a major service within the next couple of months, if Audi don't say anything I'll plug VCDS into it and see whats what. My last chance saloon will be a new sensor and gel pack, I am pretty confident that's where the problem is given the symptoms but I'll report back once I've nailed the cause down.
     

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