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Detailed Instructions - Operation of the Windshield Wiper & Washer System

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Tail Spin

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Discussion starter · #1 ·
Wipers

First time eI was out in the rain in my (wife's) new Phaeton.
Wiper lever- 1 click up- Auto rain sensor w/ intermittent (right?)
Wiper lever- 1 click up then a twist of the dial on the stalk (manual override of intermittent, driver ability to adjust frequency?)
What I did not understand was that when I twisted the dial to either increase or decrease the frequency, the wipers responded but in this setting instead of individual sweeps the swept in w/ 4 continuous sweeps then paused then repeated the patter?
I would think they would sweep in individual pulses?
Any input?
Thanks.
 
#2 ·
Re: Wipers (Tail Spin)

My experience has been that they do sweep in individual pulses when they are on the intermittent setting (the first notch up from 'off' when you lift the control arm), but, whenever you adjust the sensitivity setting higher using the dial on the end of the control arm, they make a few consecutive sweeps before settling down and functioning normally at the new setting. They don't do this if you adjust the sensitivity setting lower by turning the dial in the opposite direction. I think this behavior is by design.
The intermittent wiper function relies on input from the vehicle speedsensor in addition to input from the rain sensor that is mounted in the top middle of the windshield. If there is any problem with the signal provided to the wiper control unit from the speedsensor, then the intermittent wiper setting will give squirrely results.
My suggestion is that you hang in there until you have a few days experience driving in rain, to allow you to get used to how it behaves. If you find that the behavior of the wipers is erratic when you are using the intermittent setting, ask your service technician to check and see if the car has generated any fault codes (in any control module) that mention the speedsensor. Assuming that the rainsensor is working properly, the speedsensor is the next thing to look at when troubleshooting problems with intermittent wiper operation.
Michael
 
Discussion starter · #3 ·
Re: Wipers (PanEuropean)

OK, thanks.
They were just a little too ambitous and I was trying to calm them down.
I also agree I need more experience with them.
Thanks.
So where do you fly? I live near KMMU.
 
#4 ·
rain sensor wiper

Just noticed today....
if you leave the wiper on the rain sensor setting, turn off the engine, and then restart later, the wipers don't sweep - you have clear the windshield manually first, and then set the wiper to the rain sensor setting again (I guess the rain sensor is a "differential" type - it looks at the windshield when activated and determines when there are enough droplets that need to be cleaned... when first set on the rain sensor, the wipers sweep once and start, but if the blades are already on this setting, they never sweep before starting - hence - the system thinks that the windows are "clean") - just my speculation, but seems to me like that's how they work
 
#5 ·
Re: (mkla2000)

I think that I have noticed the same issue that John pointed out... I also have had to "reset" the auto wiper functionality after restarting the car - (by turning them to either on or off, and then back to the auto setting). I haven't had a chance to look into this closely, nor have I paid that much attention to it... But I do recall sharing this anomaly.
Douglas
 
#6 ·
Re: rain sensor wiper (mkla2000)

I am going to guess that the fact that the wipers don't function on when on the rainsensor setting, following a power-down cycle, is intentional. For example, if you parked the car, then got into it the next morning and there was a little bit of dew over the rainsensor, the wipers might sweep when you really don't want them to sweep.
The key question is: If the wipers are left at the rainsensor position, the car is powered down and then powered up again, will the rainsensor automatically activate the wipers if water is detected on the windshield once the vehicle is in motion? I seem to recall, from past experience, that as long as the vehicle is in motion, the rainsensor will function across start cycles. I'm just guessing that it is intentionally inhibited from causing the wipers to sweep if there is water on the glass when the vehicle is started up, but the transmission selector is still in Park.
Perhaps someone could do an experiment with their garden hose - turn the car off, leave the wipers in the rainsensor position, spray some water on the glass, then back out of the driveway (in other words, start moving) and see if the wipers function once the car is in motion.
Michael


Modified by PanEuropean at 5:15 PM 1-7-2005
 
#7 ·
Re: rain sensor wiper (mkla2000)

I thought I remembered something in the manual on this as I had originally thought I would just leave the wipers on until I read this. Anyway, I tried to scna it, but the book proved to be a challenge. So I'll just copy the text from 3.1.1 page 68.
The rain sensor is part of the interval wiper fucntion. You will have to switch on the rain sensor back on if you switch off the ignition. Reset the rain sensor by switching the wiper interval function off and back on.
I think that corborates the comments above ...
 
#8 ·
Re: rain sensor wiper

This not working across re-starts is discussed in the manual. I was surprised to find it in the Phaeton as this is also the way the sensor works in my 2001 Passat 4-motion wagon; it always struck me as odd to have to re-set it. (I once had a MB E-class with this feature and I could always leave it in the sensor mode and it work when it needed to.)
My friend in Germany says his European Phaeton does not work this way, but resumes wiping after a re-start.
Robert
 
#9 ·
Re: rain sensor wiper (whealy)

Quote, originally posted by Bill »
I thought I remembered something in the manual on this as I had originally thought I would just leave the wipers on until I read this. Anyway, I tried to scan it, but the book proved to be a challenge. So I'll just copy the text from 3.1.1 page 68.
The rain sensor is part of the interval wiper function. You will have to switch on the rain sensor back on if you switch off the ignition. Reset the rain sensor by switching the wiper interval function off and back on.
I think that corroborates the comments above ...

Hi Bill:
Thanks ever so much for doing the research on this - we have a joke in the aviation industry, whenever someone is unsure of how one of the aircraft components is supposed to function, the usual wisecrack is "RTFM" - not sure if that carries over to Phaeton ownership or not.
Image

As some of you know, while I am in Africa, the Phaeton techs at the VW dealer I use in Zurich are collecting diagnostic scans for me from European Phaetons. Once I pick these up, if I see a difference in the software settings for the wiper control module that we can change to enable rainsensor operation across start cycles, I will post the details here.
In the meantime, to reset the rainsensor so that it will continue to operate after the car has been powered off, I think all we have to do is just move the wiper stalk down to the 'OFF' position and then back up to the 'Intermittent' position - I don't think we need to mess up whatever setting we have chosen (after great experimentation) on the rainsensor sensitivity dial.
Michael
 
#10 · (Edited)
Re: rain sensor wiper (rljones)

For those who may be curious, here is a picture that shows the location of the rainsensor that supplies input to the windshield wiper controller when the wipers are operating in the 'intermittent' position.
The rainsensor is located at the top center of the windshield, just slightly towards the driver side. On right hand drive cars, it will also be on the driver side. The opposite side (unused) rainsensor mounting position is where the Homelink transmitter for the garage door opener function is placed.
If you look very closely at the forward end of the arm that the inside rear view mirror is mounted on, you will see another sensor there. I'm not entirely sure what that one is for - it is either a light sensor used for the automatic dimming rear view mirrors (all three of them), or, it might be the humidity sensor that detects condensation on the inside of the windshield and automatically turns on the air conditioning compressor to dry out the cabin air. I kind of suspect it is the humidity sensor, but I am not 100% sure. It is a very tiny hole, hence the warning in the owner manual to not hang parking permits, etc. from the rear view mirror, or put stickers on the windshield directly in front of the rear view mirror.
Michael
Rainsensor Location
Image
 
#11 · (Edited)
Re: Wipers (Tail Spin)

I noticed yesterday that the rainsensor on my Phaeton didn't seem to be working properly - it was not as 'intelligent' as it usually is about sensing the presence of rain (melted snow, actually) on the windshield.
I plugged in my diagnostic scan tool (VAG-COM) and ran a complete scan - the result was the two fault codes shown below, both associated with the roof control module ('dachmodul' in German - 'dach' means roof). The code that I think points out the source of the poor rainsensor performance is the first one, the intermittent connection to the rainsensor itself.
I will disassemble things and have a look at this tonight when my wife brings the car home. I don't know what the underlying cause of the problem is - I suspect perhaps a connector that is not properly supported (meaning, the connector is loose, it is not resting on a solid surface, and perhaps the weight of the cable is occasionally causing the contacts to separate). This might have been a result of careless assembly on my part when I took the roof control module apart a month or so ago (see this thread: Removing the Front Overhead Control Panel).
It is really interesting to note how easy it is to diagnose the cause of problems on a Phaeton - the self-diagnostic capabilities of this car are amazing.
Michael
Diagnostic report showing cause of poor rainsensor performance
Image
 
#12 ·
Rain Sensor Function

As anyone in a cold climate knows, wipers are vulnerable to freezing to the windshield. If frozen, the drive motor can be damaged.
VW has wisely configured the system to not reactivate at restart to protect the drive motor.
This is only needed on an automatic system, as the driver may not remember to turn it back to off in cold weather like they would with a manual system that is periodically moving just before car shutdown.
 
#13 ·
Re: Rain Sensor Function (GTINC)

As a new owner I was poring over the manual last night, and read the boxed-out paragraph concerning the rain sensor deactivating in the event of switching off the ignition. Personally speaking, I think it's an annoyance, but only a slight one - and I can see the reasons for VW doing it.
 
#14 ·
Re: rain sensor wiper (mkla2000)

As a matter of standard procedure, I always switch off my wipers when I enter my garage (if it is raining outside). I wouldn't dream of leaving them on for many reasons, and I can't believe this to be a major concern for consciencious drivers.
By the way, 40 mph seems to be a point at which the wipers swing faster, even with the same amount of rain going on.
Jack
 
#15 · (Edited)
Re: Wipers (PanEuropean)

Quote, originally posted by PanEuropean »
I noticed yesterday that the rainsensor on my Phaeton didn't seem to be working properly - it was not as 'intelligent' as it usually is about sensing the presence of rain (melted snow, actually) on the windshield.
I plugged in my diagnostic scan tool (VAG-COM) and ran a complete scan - the result was the two fault codes shown below, both associated with the roof control module ('dachmodul' in German - 'dach' means roof). The code that I think points out the source of the poor rainsensor performance is the first one, the intermittent connection to the rainsensor itself.
I will disassemble things and have a look at this tonight when my wife brings the car home. I don't know what the underlying cause of the problem is - I suspect perhaps a connector that is not properly supported (meaning, the connector is loose, it is not resting on a solid surface, and perhaps the weight of the cable is occasionally causing the contacts to separate). This might have been a result of careless assembly on my part when I took the roof control module apart a month or so ago (see this thread: Removing the Front Overhead Control Panel).
It is really interesting to note how easy it is to diagnose the cause of problems on a Phaeton - the self-diagnostic capabilities of this car are amazing.
Michael
Diagnostic report showing cause of poor rainsensor performance
Image

We've learned a few things in the two months since this thread was last active. One is that the fault code concerning the sunroof is spurious and can be safely ignored - every Phaeton that came to the Phaeton Owner GTG in Auburn Hills had this same fault code, and no-one was having any sunroof problems.
The second thing is that any kind of buildup of wax or rinse agent on the windshield will degrade rainsensor performance. All automatic car washes - especially 'touchless' automatic car washes - add either wax or a rinse agent (same as dishwasher rinse agent) to the final rinse, to help the water sheet up and roll off the car when it goes through the blowers. These waxes and rinse agents build up on the windshield, and interfere with the rainsensor, which measures the refractive properties of the glass to determine if there is water on it or not.
The best cleaner to use to clean the outside of the windshield, over the spot where the rainsensor is, is BonAmi cleanser - the 'old fashioned' formula with the picture of the chick on the front of it (baby bird, I mean, not a bimbo) and the words "safe for Fiberglass" on the can. This cleanser contains Feldspar, which is a very, very soft abrasive. Find an old facecloth, get it wet, sprinkle some BonAmi on it, and gently rub the area over the rainsensor. Then rinse the mess off with a hose. After you have done that, moisten another cloth with pure isopropyl alcohol, and it rub (hard) over the same area. This will clean the glass really, really well.
If you do this about once every 2 months, assuming you live in an area with 'average' industrial pollution, the rainsensor will continue to work at top performance.
Michael


Modified by PanEuropean at 1:11 PM 11-2-2008
 
#16 ·
Re: Wipers (PanEuropean)

Thanks for that info Michael as I too have not been able to establish a "happy" position for my rain sensor function. Just as I believe position 3 is the best position, I then notice it's too sensitive and I move it to "2". It works great for a while then later I end up moving it back to "3". The cycle of change never settles. I use touchless car washes also . In my opinion though, a true rain sensor position should not have several positions to choose from if it truly senses rain. On my Benz, I had a rain sensing position which worked great and adjusted its speed based on the amount of rain, then there was a "slow" and a "high" non-rain- sensing position. I always used the 1st position (rain sensing) and never touched it again as it worked so well.
The Phaeton needs improving in this area. Just my .04 worth.
 
#17 ·
Re: Wipers (dcowan699)

Hi David:
I have gone through four different opinions of the automatic wiper system on the Phaeton:
1) The weekend I had my dealer's demo, before I bought my car (it rained all weekend) - I thought the system was perfect.
2) The first month I had my car, I was really happy with it - it operated the same as the demo did.
3) After the first month, it never seemed to work right, and I was pretty annoyed with it - both the technician at my dealership and myself spent quite a bit of time troubleshooting it (electrically), with no improvement.
4) Once I discovered the "BonAmi and IPA" trick to clean the wax, chemical film, and industrial fallout off the glass where the rainsensor mounts (just on the driver side of the rear view mirror) - now it works perfectly again, just like 1) and 2).
The thing is a refractometer - anything that changes the refractive properties of the glass will have a profound effect on the performance of the rainsensor. Give the BonAmi and IPA routine a try, and see how it goes. Use lots of BonAmi, but only press GENTLY - like you were washing a child's face - when you are using the BonAmi. Press really hard later on when you are using the IPA.
Michael
 
#18 ·
#19 ·
Re: Wipers (PanEuropean)

Quote, originally posted by PanEuropean »
4) Once I discovered the "BonAmi and IPA" trick to clean the wax, chemical film, and industrial fallout off the glass where the rainsensor mounts (just on the driver side of the rear view mirror) - now it works perfectly again, just like 1) and 2).

For those of you who are reluctant to use BonAmi cleanser (even though you shouldn't have any problems), paint clay (the same kind used by detailers to remove oxidation & dirt from paint) will work as well. Use the clay on the windshield as you would on the paint, rinse the windshield well w/ a hose, dry off and as a final touch, use the IPA Michael referenced. Good a new and you'll probably find the wipers are no longer leaving that milky white film on the windshield as they wipe. (Cleaning the blades with Windex or similar will also help keep them functioning well.)
 
#20 ·
Re: Wipers (chrisj428)

Hi Chris:
Thanks for adding that information.
There is a PDF file available here on the forum that provides additional information about how to use paint clay. It explains how to perform the pre-delivery inspection of a VW. I have found it very useful, because it lists all the different cleaners, chemicals, and materials that VW approves for use on their cars. Here's a link to the thread with that PDF - it is attached to bottom of the second post in the thread: Volkswagen Recommended Care Products. The information about using paint clay is on page 23 of the PDF.
Michael
 
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