IDEAS: Bypassing / overriding the rain sensor's control of intermittent wiping delay

[volvofan]

Okay, so I've been trying to retrofit a couple of goodies to my BASE model B7 A4. Added CH/LH, DRL, trip computer, and auto headlight switch, for starters. Finally got it all VCDS-coded and functioning properly and error-code free. Unfortunately, to keep from flagging an error code (maybe because I have the trip computer option enabled?), I had to actually add a rain/light sensor to the system. Although there is supposedly a VCDS code to disable the sensor (and I've tried virtually every combination/permutation of those settings), I can't get it to do so in order to regain control of my intermittent wiper delay time. This is apparently a common lament from many Audi owners of all different models.

I had a spare wiper stalk (from when I did the trip computer retrofit) so I did what any engineer would... pulled it apart to see how it worked, then probed it. The four pins (remember, no trip computer) are organized into two pairs.

The pair on the right (as you look at the BACK side of the switch, held upright... like you were sitting inside the engine bay with x-ray vision) changes resistance across the pins depending on stalk position:
Hi: 11.25 k Ohms
Lo: 9.07 k Ohms
Int: 9.75 k Ohms
Off: 17.46 k Ohms
1x: 9.07 k Ohms (the momentary position for a single wipe)

On the left, the resistance changes as you roll the intermittent delay switch through its various positions:

4: 8720 Ohms (highest # of wipes per minute)
3: 2513 Ohms
2: 1015 Ohms
1: 337 Ohms (lowest # of wipes per minute)

I am considering a few different ways forward, but all involve retrofitting an Avant or Q7 or Q5 wiper stalk and triggering the intermittent wiping methodology of choice by putting the stalk in the "rear wiper" position.
If someone wanted to do a similar modification on a car that already had a rear wiper, they could simply add a discrete switch somewhere on the dash.

Methodology 1: Re-code VCDS to think that the car is an Avant with a rear wiper. Somehow, jump the "rear wipe" output command to the "single front wipe" command.
Advantages: Minimal wiring required... probably only need to cut or splice a couple of signal wires
Disadvantages: Only one intermittent speed for your front wipers... approx. 1 wipe every 4 seconds.

Methodology 2: Add a control module that reads the existing delay switch's position and translates that into a wipe delay. Send that wipe command either to the control module or directly to the wiper motor.
Advantages: Most "OEM" functionality.
Disadvantages: Most wiring required... need to read both the wiper stalk position (to turn module on/off) AND the delay switch position (to determine delay).

Methodology 3: Add a control module that uses the "99" programmable wiper delay relay (a VW/Audi relay that Volvo folks frequently retrofit due to our lack of adjustable delay on older cars) to send the wipe command to either the control module or directly to the wiper motor. That relay allows you to "program" the time delay you want by moving the stalk to the intermittent position, then moving it back to off, then back to intermittent after the desired time. Sounds complicated, but it becomes quite intuitive after a short period of time.
Advantages: Most flexibility (delay is user-adjustable anywhere from .5-20 seconds); less wiring required... only need to read wiper stalk position to turn module on/off.
Disadvantages: Less "OEM" than #2, more complex than #1.


Looking forward to hearing everyone's thoughts on the subject.

-Jon

[Audibot]

My B7 came with the rain sensor and trip computer both. I thought the light sensor was the thing on the center of the dash, while the rain sensor was the unit (with the gel pad) that sat behind the rearview mirror. I do recall there being a VCDS setting for having a rain sensor or not.

Sorry if I am asking a stupid questions:

1. What does the wiping interval for you do right now? That is, do you have any wiping interval or not? I felt like the only time the car had rain sensor control was if I left the wipers on and at the lowest setting and they would auto adjust. Other than that, it utilized the predetermined wiping interval.

2. When you added the rain sensor, has it been connected up on the windshield as required, and with the gel pad?



Of your options, #3 looks like it provides you the best bang for the buck--Option 1 (once every 4 seconds) is just looking for an accident to occur.

[volvofan]

My B7 came with the rain sensor and trip computer both. I thought the light sensor was the thing on the center of the dash, while the rain sensor was the unit (with the gel pad) that sat behind the rearview mirror. I do recall there being a VCDS setting for having a rain sensor or not.

Sorry if I am asking a stupid questions:

1. What does the wiping interval for you do right now? That is, do you have any wiping interval or not? I felt like the only time the car had rain sensor control was if I left the wipers on and at the lowest setting and they would auto adjust. Other than that, it utilized the predetermined wiping interval.

2. When you added the rain sensor, has it been connected up on the windshield as required, and with the gel pad?



Of your options, #3 looks like it provides you the best bang for the buck--Option 1 (once every 4 seconds) is just looking for an accident to occur.

Not stupid questions at all! I had to learn a lot of this by trial and error myself.

There is a light sensor in the dash for ALL models... that controls different stuff than the rain/light sensor combo that is up behind the rear view mirror as you described.

1) Wiper stalk positions momentary (single wipe), off, low, and high all work identically for all models, with or without the rain sensor. On models without rain/light sensor installed (or with rain/light sensor turned off, which I don't want to do because it throws an error and disables my CH/LH function), the intermittent setting has variable time delays controlled by the "rolling" switch embedded in the stalk. On models with rain/light sensor installed, the "rolling" switch instead controls the sensitivity of the rain sensor.

2) Right now, I have the rain/light sensor tucked away under the dashboard. I might eventually attach it to the windshield but for now, it thinks it's dark and not rainy all the time.

-Jon

[Audibot]

Thanks. I think I got it. Because your rain sensor is not in the proper position, you essentially have no intermittent function because it cannot sense something. Is that right?

Since the end of winter is almost at hand (knock on wood), could you, say, "get a crack" in your windshield and have it replaced with an OE rain sensing one via insurance? I accidentally cracked mine some years back when I was washing the car. I had removed the blade to clean it, and then accidentally bumped the arm and it swung down to make a nice little crack at the impact site. Over a couple weeks that crack grew from one wiper up, over, and back down to the other wiper.

[volvofan]

That is correct. My concern is, given the angst that seems prevalent throughout the Audi community about how the rain sensing feature performs, I'm trying to decide if it's worth it at all to install the doggone thing, only to find out that it wipes when it shouldn't and doesn't wipe when it should.

If I do decide to install it, I won't need to replace the windshield to do so. I'll just fab up a mount and tuck it up in the area around the rear view mirror. I already have my EZ Pass and garage door opener stuck up there as it is, so one more gadget stuck to the windshield in that area won't hurt my feelings.

-Jon

[Audibot]

Was there angst? I mean, I personally never had an issue with it and instead loved it. It always wiped when appropriate and stopped when there was nothing to wipe.

Got it. If you need the appropriate rearview, I should be able to help you. I have a black one, and am 90% confident I have a satin one in my basement.

[volvofan]

It's probably a small but vocal subset of owners. It's not like you can run a google search for "how many Audi owners DON'T hate their rain-sensing wipers" but a query of "Disabling Audi rain-sensing wipers" generates plenty of hits. People don't bitch to the internet when everything is going fine :)

[Audibot]

Agreed. Part of me thinks just fabbing up that bracket and seeing if it all works as-designed may be the easiest route of all.

[p0isin]

I hate the rain sensing feature. Even after changing the light transmission value with VCDS it is very unpredictable. Interested to see what you come up with.

[volvofan]

Agreed. Part of me thinks just fabbing up that bracket and seeing if it all works as-designed may be the easiest route of all.

Good point... no harm in trying the status quo for a while!

Thx,

-Jon

[volvofan]

Okay, got my ghetto sensor mount all fabbed up. Extended the three wires, tucked everything into the A pillar and headliner trim, and popped out by the rear view mirror. My EZ Pass is sitting between the rear view and the headliner, so I ran the sensor wire down the passenger side of it so I wouldn't see it from the driver's seat. Then, I put a notch in a black Powerade cap and put a thin bead of super glue around it to adhere it to the windscreen. I'll try it for a month or so then decide how to proceed.

-Jon

[volvofan]

Okay, got my ghetto sensor mount all fabbed up. Extended the three wires, tucked everything into the A pillar and headliner trim, and popped out by the rear view mirror. My EZ Pass is sitting between the rear view and the headliner, so I ran the sensor wire down the passenger side of it so I wouldn't see it from the driver's seat. Then, I put a notch in a black Powerade cap and put a thin bead of super glue around it to adhere it to the windscreen. I'll try it for a month or so then decide how to proceed.

-Jon

Okay, so it rained for most of last week and my suspicion was confirmed... I really don't like the rain sensing feature. Even with the slightest mist and the sensitivity turned all the way down on the wiper stalk, the wipers run like a raped ape. I went into VCDS and disabled speed-sensitive wiper speed and also turned down the transmissivity of the glass. We'll see if that helps... won't know until next time it rains. In the meantime, I have a Q7 wiper stalk on the way, as well as a programmable "99" relay, so I am prepared to try that route out. I think I'm going to have to hijack the signal out of the switch itself, rather than try to pick up that the rear wiper has been triggered somehow by the CECM, because it would probably only do that intermittently. Will be easier to just trigger the relay old-school and have it piggyback right onto the wires that go to the motor, bypassing the steering column control module AND the CECM entirely.

More to follow,

-Jon

[volvofan]

Plenty more rain today and despite turning transmissivity down to 20%, the wipers were still going batshit. The Q7 stalk arrived today and I pulled it apart to look at its guts. The circuit board inside is actually exactly the same as the basic stalk, minus the pass-through pin for the trip computer. In both switches, there is a mini-PCB with surface-mount resistors for the "roller" switch, whose signal comes out the pair of pins I previously identified. The PCB shown in the photos has the resistors for the stalk position (low, high, intermittent, etc) AND the push/pull position (windshield spray, rear wipe, rear spray). All read out through the same pair of pins I previously identified.

Two ways to go about this: first, COMPLETELY BYPASS all things Audi. Install a small switch into the back/bottom of the stalk and use it to trigger the programmable relay. Second, the way I hope to use... hijack the signal that shows the stalk in the "rear wipe" position to trigger the relay. I installed a tap wire as shown in the pics, and will see what it reads once actually installed in the car. Since the whole rest of the switchology is resistance-based, I just have to hope that, by tapping into the signal, I do not alter the outputted resistance in such a way that the other functions are affected. I won't know until it is installed, so more to follow in the coming several days!

-Jon

[DougL]

Why not either:

A. Disable it 100% with vag com coding
B. Customize it with vag com adaptation channels

I think central electronics - 19

Xxxx: Body
0 - Sedan
1 - Avant
2 - Cabrio

X? Xxx: Light and rain sensor

0 - none
1 - installed

Xx? Xx: hook module

0 - none
1 - installed

Xxx? X: headlights

0 - Halogen without DLR
1 - Halogen with DLR
2 - BiXenon with DLR
3 - BiXenon without DLR
4 - BiXenon with DLR (+ license plate light and rear automatic lights)

Xxxx ?: Country

1 - Rest of World / Scandinavian countries / Denmark / Croatia / Baltic states (Bi-xenon)
2 - Scandinavian countries / Denmark / Croatia / Baltic countries (without Bi-xenon)
3 - USA / Canada (Bi-xenon)
4 - Canada (without bi-xenon)
5 - special vehicles



and customize or disable:

Adaptation channel 13

Standard: 115

+001 = Speed ​​Rest

+002 = Short to Plus Monitoring

+004 = Rain Sensor active

+008 = Long Post Wiping After Washing (Drop / Tear Wiping)

+016 = Speed ​​Dependent Wiper Interval Active

+032 = Headlight Washer System active

+064 = Reverse Gear Wiping active



Adaption channel 22 adjust the sensitivity of the rain sensor

The standard is 45

[volvofan]

Why not either:

A. Disable it 100% with vag com coding
B. Customize it with vag com adaptation channels

I think central electronics - 19

Xxxx: Body
0 - Sedan
1 - Avant
2 - Cabrio

X? Xxx: Light and rain sensor

0 - none
1 - installed

Xx? Xx: hook module

0 - none
1 - installed

Xxx? X: headlights

0 - Halogen without DLR
1 - Halogen with DLR
2 - BiXenon with DLR
3 - BiXenon without DLR
4 - BiXenon with DLR (+ license plate light and rear automatic lights)

Xxxx ?: Country

1 - Rest of World / Scandinavian countries / Denmark / Croatia / Baltic states (Bi-xenon)
2 - Scandinavian countries / Denmark / Croatia / Baltic countries (without Bi-xenon)
3 - USA / Canada (Bi-xenon)
4 - Canada (without bi-xenon)
5 - special vehicles



and customize or disable:

Adaptation channel 13

Standard: 115

+001 = Speed ​​Rest

+002 = Short to Plus Monitoring

+004 = Rain Sensor active

+008 = Long Post Wiping After Washing (Drop / Tear Wiping)

+016 = Speed ​​Dependent Wiper Interval Active

+032 = Headlight Washer System active

+064 = Reverse Gear Wiping active



Adaption channel 22 adjust the sensitivity of the rain sensor

The standard is 45

Don't I wish it was that easy!

Central electronics (Module 09) - if I disable the light/rain sensor entirely, then my CH/LH switch and DRL will cease to function properly.

Adaptation channel 13 - I tried subtracting 4 to disable the rain sensor only. In fact, I tried EVERY SINGLE POSSIBILITY (from zero to 128) and had no luck regaining time-delayed control of my intermittent wipers.

Adaptation channel 22 - I've dialed it down to 20. It's better, but still not quite there. I may adjust it a little further down to see if I can bracket in on the range where I can control the sensitivity satisfactorily via the roller switch. STILL, there will be times I want to initiate time-delayed wiping, so even if I get the rain-sensing wiper feature tuned well, I'd still like the option to have delay based on time vs. what the sensor sees (or thinks it sees).

-Jon

[volvofan]

Okay, so I got the wiper stalk installed and started probing and testing.

The bad news is, the"pigtail" off of the switch itself is basically useless. If you were scared off from the idea of this modification when you saw the guts of the switch and the soldering iron, fear not... you will not have to do that!

The good news is, if you enable the rear wiper (under VCDS coding for Steering Wheel Electronics, change last digit from 1 to 2), you can hear relays come to life under the dash when you push the stalk away from you. A little ELSAWin wiring diagram research led me to probe pins 17 and 14 on the T23 (NOT T32) CECM connector. Both start out at +12V with the stalk in the normal position, and drop to 0V once the stalk is pushed away from you one click (i.e. to the "rear wipe" position).

It would have been better if it went to +12V when pushed away and remained at 0V when in the normal position, but beggars can't be choosers. My biggest concern was that the CECM put an intermittent pulse into those wires, so I would be unable to use them to trigger the programmable relay. Instead, it's a nice constant 12V, so that's a big help. There must be some other control module that's part of the rear wiper system that does the intermittent part, but that's not my problem anyhow :)

Now to figure out how to use the 12V signal to trigger my programmable delay relay... AND to figure out which wires to trigger with it. I think I can tap into the juice that goes to the main wiper motor right there at T32b or T10b on the CECM.

More to follow.

-Jon

[Okedokey]

If you swap the wires it will be 0 at standard position 12 at others, you can then use a 12V offset or 555 timer to PWM the delay circuit.

[volvofan]

If you swap the wires it will be 0 at standard position 12 at others, you can then use a 12V offset or 555 timer to PWM the delay circuit.

Not sure which wires you're suggesting I swap. When testing across them both I got no voltage reading in any position. When testing across either wire to ground, that's when I saw 12v in normal position and 0v when stalk was pushed back.

-Jon

[Okedokey]

Yeah it really doesn't matter anyway, its a potential difference, so any combination of logic will work. Applying 12V to a negative (not ground) compared to 12V = 0V so you can set the logic up whichever way you want.

[volvofan]

I posted this over in the B7 A4 Tech thread, but it has not yet been approved by a Mod and I've had some questions about progress on this. As such, I'm re-posting here. Hope this helps!

-Jon

Okay, folks, I finally cracked the nut on this one after several hours of searching and weeks of engineering possible solutions. In the end, the final solution was not too complicated to implement and it works perfectly. The best time to do this retrofit (if you're using the wiper stalk method) is at the same time as you upgrade to a trip computer-capable wiper stalk... that way you only have to take the steering wheel off once!

I have an '07 B7 A4 sedan that came with basically ZERO options. I wanted auto headlight control, DRL, and CH/LH functionality (all through the OEM switches), but if you've looked into doing those retrofits you'll see that you have to install the rain/light sensor or you'll get error codes (I did the trip computer retrofit, too, so maybe that's why?) and/or it won't work properly. For some folks, retrofitting the rain/light sensor is no issue because they want the auto-dimming rear view mirror and all that jazz, too... I didn't care about that stuff so I just fabbed something up to hold the sensor in place behind the regular ol' rear view mirror. Now all my upgraded lighting features work as they should... yay!

That's when I noticed an unfortunate by-product of all of this work... the rain sensor is a pain in the ass. It runs like a scalded cat in even the slightest of mist, and I couldn't simply set the duration between wipes (i.e. 1 second, 4 seconds, etc) like I used to be able to do with the wiper stalk in the intermittent position. Instead, the switch that used to change time between wipes now adjusts the sensitivity of the rain sensor (stock range goes from "insane" to "slightly less insane"). Off to VCDS we go! Unfortunately, the adaptation channel 13 in Central Electronics Module 09 that one would THINK would allow me to disable the rain sensor seemed to have no effect. I have reprogrammed the window transmissivity (channel 22) from the default 45% down to about 15%, and that has helped a great deal... now I actually like the rain sensing feature sometimes. BUT, I still wanted the ability to set the intermittent delay of the wipers based on TIME, not what the sensor / computer thought was best.


On to the DIY part!

WHAT YOU'LL NEED:
a) Standard wiring tools (needle nose pliers, wire strippers, soldering iron, crimpers, etc.)
b) 12/14 gauge wire, about 2 feet of it
c) 18/20 gauge wire, about 4 feet of it (more, if you're adding your own switch vs. using the wiper stalk)
d) Wire taps, spade connectors, heat shrink tubing, fabric electrical tape, zip ties... the usual suspects for an electrical retrofit.
e) A VW/Audi "Type 99" or "Type 197" programmable delay wiper relay
f) A normally open (NO) switch of your choice (if not using the wiper stalk)
IF YOU ARE USING THE WIPER STALK METHOD, you'll also need the following components:
g) A new wiper stalk from a vehicle equipped with a rear wiper, OR the willingness to take your own switch apart and remove a piece of plastic that currently prevents you from pushing the stalk away from the driver.
h) VCDS software & cable
i) A standard 5-pin 12V automotive relay... it must have a "NORMALLY OPEN" contact (usually terminal 87a)
j) A T8 screwdriver. NOT just a 1/4" hex bit. If you have a T10 that's a bit worn down, you might be able to get away with it if you push hard enough. Ask me how I know. Once I got them out, I replaced the screws with Phillips heads :)
k) An M12 Triple Square (male) bit for the steering wheel
l) A 10mm socket for the negative battery terminal.

I will do this DIY from here on out as though you're doing it on a car without a rear wiper, and hence, will be using the wiper stalk to trigger the relay instead of an add-on switch. If you're using the add-on switch method, the steps you'll be able to skip will be obvious.

1) Install the new wiper stalk. It's plug and play... follow the directions found in the "trip computer retrofit" thread here:

http://www.audizine.com/forum/showth...puter-Retrofit

I know all the pretty pictures are on the first page, but read ALL three pages. There are some good tips on the second and third page - ESPECIALLY the part about the steering wheel bolt being a Triple Square (M12, I think) and NOT a T55 Torx!

1a) If you've decided to reuse your own non-rear-wiper-capable wiper stalk, you'll need to somehow bust out the plastic ridge shown below that currently prevents your stalk from being pushed away from the driver. I DID NOT DO THIS, PERSONALLY... so I can't guarantee 100% that it will work as advertised. However, I did open up the new stalk before I installed it, and opened up my pre-trip-computer one for comparison as shown. It "SHOULD" do the trick and you can save yourself $50 or so. Two T8 screws hold the cover on the switch... remove them and carefully pry up the plastic tabs that are opposite the screws. The cover will come off and the guts will try to come out (they are under a bit of spring tension) so pay attention to how it all goes back together before you remove the stalk itself. You have to get the actuating arms back into the slots on the sliding switches or the switch won't work properly after reassembly. There are some more detailed pictures of the inside of the switch in my initial "ideas" post linked earlier in this write-up.



2) Program VCDS. Set the module 16 coding to 0xxx2. This tells the car that there is a rear wiper system. Now you can test to see if you did the switch correctly... when you push the switch away from the driver, you will hear a relay "click". I couldn't find said relay, so I presume it's something actually inside the CECM. I was happy enough to be able to get a 12V / 0V signal on one of the CECM wires, so I didn't feel the need to crack the thing open and see if I could avoid using a second relay to trigger the wiper relay.

3) Assemble your relays & wiring harness. I used the fabric electrical tape to attach the relays back to back. Not shown in the photo, I later wrapped them in a piece of foam before placing them under the dash in order to minimize the clicking noise I knew I would soon hear. Wiring harness diagram is shown below, but here's the write-up for the pinouts:

Type 99/197 relay:
Pin 15 gets ignition +12V by tapping into CECM T10b/5, a black/yellow large gauge wire. That is fed by the 30 amp fuse #36 for the "wiper system." You should have TWO wires coming out of your spade connector for Pin 15... the second one goes to Pin 30 on the other relay.
CUT the Black/white heavier gauge wire from T10b/8 that goes to the wiper motor. Put the CECM side of the wire into Pin 53s (s is presumably for "switch") Put the motor side of the wire into Pin 53m (any guesses as to what "m" stands for?)
Pin 31 goes to ground... I tapped into CECM Pin T23/20. Like with our +12v source, this spade connector needs TWO wires coming out of it; route the second one to pin 85 on the other relay.
Pin "I" is your intermittent trigger pin. If not using the wiper stalk, you just feed +12V to it via a switch in order to activate it. In our case, we're going to use a relay to give that pin +12V, because unfortunately the CECM puts out 12V to the rear wiper system only when the switch is NOT pushed away from the driver (the opposite of what we need). Connect Pin "I" to Pin 87a of the other relay.

Other relay:
Pin 87a goes to Pin "I" on the intermittent relay.
Cover or cap off Pin 87, because otherwise it's seeing 12V whenever your switch is not engaged.
Pin 30 goes to Pin 15 on the intermittent relay.
Pin 85 goes to Pin 31 on the intermittent relay.
Pin 86 goes to T23/14 on the CECM.



4) Install your relays & wires. Drop the panel in the driver's footwell by removing the 3x 8mm bolts that secure it in order to gain access to the CECM. I wrapped the relay pair in foam with some tape around it to hold it in place, then used a couple of zip ties to attach the relays to the sheet metal knee block that's right in front of the CECM. With a ~18" long pigtail, that was more than enough slack to reach the CECM wires. First, I disconnected the T10 and T23 connectors from the CECM, then unwrapped the fabric electrical tape around the harnesses to give me a little more access. After that, I made my cut in the wiper motor wire as described above, attached all the necessary connectors & taps, then re-wrapped everything nice and securely with more fabric electrical tape. Finally, reinstall the driver's footwell panel and test everything out.

Bring on the April showers!!!



THEORY OF OPERATION:

Here's what's happening... when the ignition is on and the wiper switch is NOT pushed away from the driver (activating our intermittent functionality), the other relay sees 12V to the coil via T23/14 and pulls the switch closed. This routes the +12V from fuse #36 to... well, nowhere. We cap and cover Pin 87 on the relay. The way the intermittent relay works, whenever it's not doing it's intermittent thing, it leaves pins 53s and 53m in contact, essentially "passing through" the relay as though it wasn't even there. That's why all the existing functionality remains unaltered.

HOWEVER...... once we push the switch to the intermittent position, T23/14 drops to ground, the relay coil de-energizes, the contact opens and redirects the +12V from fuse #36 to pin 87a, which is connected to the intermittent wiper's trigger. That +12V signal tells the intermittent relay "okay, let's do this!" and it starts pulling the 53m contact over to catch the +12V coming into its Pin 15, sending it right to the wiper motor... completely bypassing the CECM, steering wheel control module, wiper stalk, and all. Whenever the intermittent relay isn't pulling Pin 53m into momentary contact with Pin 15, it's still connected to 53s! As a result, if the wipers sense rain and you're in the intermittent position, or if you move the stalk up to the low or high position, it will still function as normal. This is one of the reasons I've turned the sensitivity WAAAAAY down on the rain sensor. If it still behaves insanely, you can actuate this timed intermittent function with the wiper stalk in the OFF position (so it doesn't get overridden by the rain sensor); you can push the stalk away from you in any and all modes. If you have it pushed away from you so that it's wiping on a time delay, then the rain gets worse and you want the wipers on all the time, move the switch up to the rain sensing, low, or high positions. Once the rain slacks off a bit, move the stalk back down to "off" (but still pushed away from you) and the intermittent timing will pick right up where it left off.


I hope this helps everyone out; please don't hesitate to shoot me a PM or reply to this thread if you have any questions or comments. I would be especially interested to know if someone was able to find a +12V signal coming off of the CECM or that relay you'll hear clicking when you enable "rear wiper installed" in VCDS, so that it could be routed directly to the "I" pin of the intermittent relay rather than having the need for the SECOND relay just to trigger the intermittent one.


Thanks!


-Jon


UPDATE: One rainy week and a half later, I've had plenty of chances to play around with the new functionality and I am still very pleased with how this retrofit is performing. Sometimes it gets a bit finicky if you've got it in the intermittent (rain sensing) position AND also using our programmable relay... I think the circuitry in the relay doesn't always know what to do with that. As a result, I find myself using two positions: Wiper stalk OFF with stalk pushed to the rear (intermittent wiping controlled by our retrofitted relay ONLY) or wiper stalk INTERMITTENT with stalk pulled forward (int. wiping controlled by rain sensing ONLY). With transmissivity set at 15% and the rocker switch in the second position from the bottom, I am satisfied with the car's rain sensing control of the wipers about 70% of the time. When it starts to displease me, I flip the switch down to OFF and push it away to take over with the programmable relay.

Second thing I've noticed (and this is VERY minor), is that the wipers do not "park" completely when being controlled by the programmable relay. They stick up just an inch or so past the bottom of the windshield. It did not take me long at all to learn to ignore this minor annoyance, as the benefit of not having my wipers running like crazy and chattering across the windscreen in a light mist far outweighs the drawback :)