My son got a school parking permit that needs to go on the windshield. Placed it there, lower right (passenger) side. It was a bit foggy/icy on the glass and he is a new driver, so I also showed him how to wash the windshield (from the car, pressing the button) for future reference as that helps clear the condensation from the glass. Well, the wiper blades almost always turn off after 3 swipes plus one extra after pressing the wash button, but in rain-sensing mode (the position I leave it in 99% of the time), they kept going and going, with the interval varying but not fully ending the wiper cycle.. I drove up and down the block to see what would happen. After a few minutes (!) they finally stopped wiping -- I was holding my breath after 10 second or so expecting them to kick in again, but fortunately they did finally stop. The windshield was completely dry well before that.

I am wondering if the sticker in that location somehow sensitized the rain-sensing nature of the wipers. It is not an OEM windshield (PGW) but I have owned car since 2009 and wipers have worked flawlessly. . It was a bit foggy (condensation on glass I mean) before I started, but I don't think I've ever seen the wipers continue to run a significant time after clearing the windshield when it is not raining.

I am wondering if it was the fog or if somehow modifying the glass or gel-pac sensitivity with an (inside) sticker on the lower passenger side. I was prepared to remove the sticker as I do not want rain-sensing mode to ALWAYS cause the wipers to be on (low speed), but it did finally stop. I'm just wondering if I am seeing a false correlation here or if it could be real.

Just thought I'd share and see what others experiences have been. I wanted to put the sticker in the rear side, but my son insisted the school says it needs to be on the windshield...

 

The sensor for the auto-wipe is behind the interior rear-view mirror.
Sometimes if it is foggy or if your wiper blades leave streaks, it can lead the auto-wipe to keep going.
I sometimes have to stop mine manually and after 30 secs switch back to auto and it then behaves normally.

 

Agreed. Mine works perfectly, but occasionally has a 'freak out' and I just turn the wipers off, and then back on again and they are fine.

Also, do you have original glass or replacement? There are other threads on here about aftermarket "just like OEM" glass screwing up the sensors.

 

The rain sensing sensor is a lens that "sees" the light scatter of the rain.
I have had a dry windshield at dawn and the system triggered unnecessarily.

 

Thanks for all the replies. As I said , it is not original windshield, but it has never done this before. My sons tells me that wipers stayed off today and yesterday. So maybe the humidity caused it, or streaking, etc. Maybe it would have reacted same in past but I was focused on it turning off. I have some (added?) sensor (or some kind of thing) on the passenger side top of windshield from original owner, so was thinking my rain sensor might have been relocated, but all seems well in any case!

 

In my car the little ring thingy which you turn back and forth on the wiper stalk doesn't seem to do much. Does that adjust how much rain is on the windshield to trigger a wiping action? I cant make out the hieroglyphics of the thing.

 

Yes, it adjusts the sensitivity/frequency.

 

Rolling up increases the sensitivity and less rain is needed to trigger the first swipe.
Down is less. Regardless of this setting, more rain causes more/faster wiping,
less rain = less wiping. Fun feature, after using the windshield washer notice that
the wipers cycle a couple of times and after they stop... one delayed wipe for the drips!