rain sensor seems too speed dependent?
Thread Starter
Track Day
Joined: May 2012
Posts: 17
Likes: 2
rain sensor seems too speed dependent?
Hello All. First Post. I love my '12 997.2 C4, ... except for the rain sensing intermittent wipers. The rain sensor seems to be too dependent on driving speed. At normal driving speed, the wiper speed is OK if set to low or mid sensitivity. But at standstill or slow driving, the wiper speed is much too slow, even at highest sensitivity. Dealer says the sensitivity cannot be adjusted. Windshield seems clean and unobstructed at the sensor location. Dealer placed the inspection sticker on the windshield very close below the mirror mount (sensor location); could that have an influence by reflection or refraction of the sensor's light beam? I have a hardwired V1 close next to the mirror mount, with the V1 cord spiraled around the mirror mount. Could that cord be causing EM interference to the sensor signal wire? Does anyone else have this problem with the rain sensor? Thanks for any suggestions.
Nordschleife Master
Joined: Feb 2011
Posts: 6,343
Likes: 1,368
From: Vancouver, BC, Canada
I don't have the exact problem you've got but I do know that the rain sensor is not perfect. It takes a while to kick in etc... I just live with and... I drive mine in the rain. All the time. He loves it. Go for it. 
Official Rennlist Snake Slayer
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Rennlist Member
Joined: Dec 2009
Posts: 3,676
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From: Charleston, SC
My Porsche doesn't have that option, so I just reach up there and turn them on, albeit not very often here in AZ.
I have another car that does have this feature, and in light rain it's slow to get going.
Imperfect science, me thinks.
I have another car that does have this feature, and in light rain it's slow to get going.
Imperfect science, me thinks.
Thread Starter
Track Day
Joined: May 2012
Posts: 17
Likes: 2
Thanks. Yeah, I'd rather just have the manual intermittent wipers... But is there anything that can be done to improve the rain sensor?
and the car loves the rain, it's a C4, so it says bring on the rain, snow, ice, mud, etc. It was awesome on slick roads last winter. Excellent handling and traction with winter tires. For fun I take it to the trash dump and the Home Depot too.
and the car loves the rain, it's a C4, so it says bring on the rain, snow, ice, mud, etc. It was awesome on slick roads last winter. Excellent handling and traction with winter tires. For fun I take it to the trash dump and the Home Depot too.
Rennlist Member
Joined: Jun 2001
Posts: 12,990
Likes: 1,448
From: North Bay Area, CA
Hello All. First Post. I love my '12 997.2 C4, ... except for the rain sensing intermittent wipers. The rain sensor seems to be too dependent on driving speed. At normal driving speed, the wiper speed is OK if set to low or mid sensitivity. But at standstill or slow driving, the wiper speed is much too slow, even at highest sensitivity. Dealer says the sensitivity cannot be adjusted. Windshield seems clean and unobstructed at the sensor location. Dealer placed the inspection sticker on the windshield very close below the mirror mount (sensor location); could that have an influence by reflection or refraction of the sensor's light beam? I have a hardwired V1 close next to the mirror mount, with the V1 cord spiraled around the mirror mount. Could that cord be causing EM interference to the sensor signal wire? Does anyone else have this problem with the rain sensor? Thanks for any suggestions.
Changing the sensitivity of the rain sensor
Sensitivity can be set with switch A in 4 stages:
Adjust switch A upwards –
high sensitivity.
The setting is confirmed by one wipe of the
windshield.
Adjust switch A downwards –low sensitivity.
Look under "Rain sensor" in the index of your manual.....
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Instructor
Joined: Dec 2010
Posts: 245
Likes: 5
Based on the owners manual you can actually disable the rain sensor. To disable the rain sensor feature simply place the right stalk in the intermittent position before starting the car. This will disable the rain sensor feature and place the wipers in the standard intermittent wiper mode.
Unfortunately, I believe you would have to do this every time you start the car since it is not persistently disabled. Just another option to try.
Unfortunately, I believe you would have to do this every time you start the car since it is not persistently disabled. Just another option to try.
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Drifting
Joined: May 2007
Posts: 2,415
Likes: 15
From: Pacific Northwest
The rain sensor system is not likely based on speed (directly) but on the appearance of rain drops on the windscreen. The faster you drive, the higher the drop impact rate on the glass becomes, and the more rain hitting the windscreen (either from faster falling rain or car hitting the falling rain faster), the faster the wipers go.
its not a perfect system.. sometimes its too slow, but it is better than having to constantly manually adjust the speed.
its not a perfect system.. sometimes its too slow, but it is better than having to constantly manually adjust the speed.
Drifting
Joined: Jan 2005
Posts: 2,616
Likes: 74
From: North Carolina
The rain sensor system is not likely based on speed (directly) but on the appearance of rain drops on the windscreen. The faster you drive, the higher the drop impact rate on the glass becomes, and the more rain hitting the windscreen (either from faster falling rain or car hitting the falling rain faster), the faster the wipers go.
its not a perfect system.. sometimes its too slow, but it is better than having to constantly manually adjust the speed.
its not a perfect system.. sometimes its too slow, but it is better than having to constantly manually adjust the speed.
Racer
Joined: May 2011
Posts: 309
Likes: 18
From: North Carolina
I drove my 2012 997S in intermittant rain today for about six hours. I had a good opportunity to get acquainted with my rain sensor function. The rain sensor only ALMOST worked in the off and on rain which also varied in intensity. I would adjust for one rain event then by the next rain cell, the sensor would not react as it had previously and would require more adjustment. I finally gave up and turned the function off. Will apply Rainx tomorrow.
I have had good results with Rainx.
I have had good results with Rainx.
Banned
Joined: Oct 2009
Posts: 731
Likes: 0
I have no issue at all with how the rain sensing wipers work in the rain. I do however have an issue with the cretin who designed the system so that it must be manually reactivated each time the engine is started. On my Mercedes if the lever is set to rain-sensing position, the system operates just like setting the headlamps to AUTO...set it and forget it.
Racer
Joined: Nov 2010
Posts: 328
Likes: 0
From: Houston, Texas, USA
I'm very happy with the auto wipers on my car. They seem to work brilliantly.