Retrofitting a heated windshield to a Skoda Yeti

Hello everyone,

After a few years of not using VCDS, I want to become active again. The reason is that I actually wanted my Yeti to have a heated seat and windshield defroster, but Skoda didn't offer this combination. I often find myself in the north during winter, which is why I decided on the heated seat. My plan was to retrofit the windshield defroster later, after the first stone chip.
Last week, the inevitable happened: my windshield cracked. I immediately contacted several workshops, but they all categorically refused to replace it, stating that they only install the same type of windshield that is already installed.

Perhaps one of you has experience with this and can point me in the right direction. I've started doing some research, and currently, my understanding is based on the following information that I've gathered from online sources:

There is an optional windshield heater or a parking heater available, but not both together.

Most people who retrofit a parking heater opt for a Webasto kit. However, I have also occasionally found original retrofitting options offered by Skoda workshops. The control can be either through replacing the Climatronic control panel with a corresponding button or via remote control. I'm not sure if that was just talk, though.

When retrofitting the windshield (without a heated seat), the process is similar. You can either build your own solution, use an additional fuse and relay connected to the mirror or rear window heating system, or use the original method by replacing the Climatronic control unit. The original fuse is number 28 in the engine compartment.

Kufatec offers a wiring harness (part number 47633), but there are no instructions included. I previously inquired about this.

In the Yeti, there is no Climatronic control panel that has both buttons. Either you have 3T0 907 044 CH for the defroster or AE for the auxiliary heater. However, in the Passat, it does exist. The part number 5K0 907 044 BH includes both buttons.

Sure, I'd be happy to help you with that. Please provide the text you would like me to translate from German to English. Once you provide the text, I will do my best to give you an accurate and natural-sounding translation.

I will also make sure to correct any errors in grammar, spelling, or punctuation. If you have any specific requests or preferences for the translation, please let me know.

My ideal solution would be to retrofit the windshield heating system as close to the original design as possible. This raises the following initial questions:

How is the original windshield heating system actually wired? Is there a separate control unit, or is it connected somewhere else?

What kind of cables do I need? Does the entire wiring harness need to be replaced, or is it enough to just tighten a few cables? When I look at what Kufatec offers, it doesn't seem too daunting.

How about the controls? The control panel with both buttons from the Passat doesn't fit into the Yeti, but the arrangement of the buttons and connectors on the back are identical. Is it possible to somehow "retrofit" the button? Can you install the circuit board from the Passat version into the housing of the Yeti version?

Vielleicht fällt euch dazu was ein. Best regards,
Christian.

Hi there.

I can't understand why workshops are unwilling to fulfill a customer's request when the customer is willing to pay for it... Who ultimately decides what gets installed, besides the customer who is paying? Unless there's some kind of legal restriction involved.

Regarding the controls, I would implement it as it was originally done in our 99 Galaxy TDI: a completely self-contained system. In that car, it's activated by a button, needs to be re-enabled every time the engine starts, and automatically shuts off after a certain period of time to protect the vehicle's electrical system.

...I'm (unfortunately) no longer surprised by things like that. There are hardly any people left who really know what they're doing. If there isn't an error code with corresponding instructions for fixing it, they're already stumped. Most workshops are only focused on making the most money with the least amount of effort.

Therefore, I hope you can help me.

I'm going to put the "DIY" option on hold for now. However, if there's no way to get it looking somewhat original, I would consider doing it myself. I suspect that the wiring harness from Kufatec might be suitable for this.

Best regards,
Christian.

PS: The last glimmer of hope I had for the repair shop vanished when I visited our car club, ÖAMTC, because my all-wheel drive system was no longer working. The mechanic told me it was fine and explained that the all-wheel drive only works if I turn off the ESC (Electronic Stability Control). After a lengthy discussion, I found myself surrounded by four mechanics who then explained to me that my all-wheel drive was working and that I couldn't even verify its function myself because as soon as one wheel spins, all the other wheels are "deactivated." I was speechless and immediately canceled my membership. After repairing the Haldex pump and spending 500 euros, the all-wheel drive started working again.

Hello Christian,

The windshield heating is controlled by a button on the climate control panel and communicates with the Body Control System (BNS) via CAN bus.


This means you need to connect the Kufatec wiring harness to the BNS (body control module) and properly code both the BNS and the climate control unit.

You've installed a Highline BNS here; you don't need to change anything.

Compare the wiring diagrams of the two control units and, if necessary, rewire them.


You need the part from Kufatec with the part number 7L3.


Does that help you get started?


Best regards,

Michael.

Thank you, Michael, that actually helps me quite a bit.

Now I know that the wiring harness is not for a DIY solution but for an original retrofit. I also received a message from Kufatec stating that there is currently no instruction manual available, but they will create one that can be downloaded directly from the product page.

The issue with the button isn't quite that simple. I have the original auxiliary heater installed, so the button is already assigned to another function.

The second button, located on the left side, is not available on the Yeti. That's why I asked above if it's possible to add it or replace the control panel with one from a Passat that has both buttons.

What would probably work is to replace or reprogram the control panel so that it activates the windshield defroster. Then I would have to use the remote control to turn on the auxiliary heater.

Where can I get the wiring diagrams? The last time I worked on the car (in 2017), you could rent access to the service manual from Skoda directly for a small fee. Is that still available, or are the diagrams now publicly accessible somewhere?

Thank you very much and best regards,
Christian.

Pumuckl wrote:

The second button, on the left side, does not exist on the Yeti. That's why there was a question above about whether it can be retrofitted? Or could a control panel from a Passat, which has both buttons, be installed?

I suspect the problem lies with the software for your control panel. The Yeti Climatronic software seems to expect either the FSH or the STH function on the left-hand button. That means that even if you add a second button, the software will probably not be able to interpret it correctly.

Pumuckl wrote:

What would probably work is to replace or reprogram the control panel so that it activates the windshield heating.

Then I would have to turn on the auxiliary heater using the remote control...

Pumuckl wrote:

I wouldn't even be sure of that. If the control panel doesn't support STH (presumably a specific feature or technology), it might also not activate the fans and flaps when STH is enabled via remote control.

Where can I get the wiring diagrams? The last time I was working on the car (in 2017), you could rent access to the service manual from Skoda directly for a small fee. Is that still available, or are the plans now publicly accessible somewhere?}
Can you still purchase a short-term access to Volkswagen vehicles at a low price?


The Passat control unit supports both buttons at least in terms of hardware and software. Therefore, I think you have the best basis with it. However, it will be interesting to see whether this control unit can be properly coded for the Yeti. I suspect there will be some incompatibility here, and no one will be able to predict which Passat control unit has the best chance of being compatible with the Yeti.

In short: I believe it's possible that there might not be any software that supports both buttons and all Yeti control units/Yeti CAN messages. However, I am absolutely not an expert on the extent to which Passat and Yeti CAN messages differ.

Hello Christian,

Don't stress yourself out about it. You've taken on a nice project. You can modify it. Before you start, make sure to compare the wiring diagrams and programming codes for each control panel.

If you find it easy to compare wiring diagrams and have some understanding of the CAN bus system, it's not that complicated.

I installed the climate control unit from a Golf 6 into a Touran 1T1. When controlling the recirculation flap, I had to install a potentiometer because the control signal wasn't compatible. The Touran originally only had a basic air conditioning system and was supposed to get an automatic climate control system. Also, the Touran didn't have an air quality sensor. I had to replace the BNS (Body Control Module) and the Gateway. Even with the Touran, simple coding was enough to make everything work.

You already have a Highline vehicle, which means the BNS and Gateway are also Highline versions. You have an air quality sensor installed in the vehicle. The costs remain manageable.

You need the Kufatec wiring harness for a vehicle WITHOUT start/stop functionality. The Kufatec wiring harness essentially only has three wires: a wire to the fuse, a ground wire, and a control wire from the BNS (Body Control Module).

You need to make sure that the climate control unit supports all the functions you require, and that the part numbers (PR codes) are correct.


If you experience any problems with the auxiliary heater, you can use a (GSM) remote control.

You can also read the CAN command for the auxiliary heater from the old climate control unit and use a CAN-compatible relay to implement it.

This means the relay reacts to a CAN command from the Passat (which may not be compatible) and then sends the correct CAN command from the Yeti onto the bus.

However, the differences within the platform are likely not to be that significant.

You can also test this very well using Rainer's CAN tool.



Best regards,

Michael.

Hello Michael,

I ordered the cable before. If I have time this weekend, I'll take apart the control panel and see if it would be possible to replace the Braille button.

It would be interesting to see if anyone has photos of the circuit board from the Passat part with both buttons. I've searched on the usual online marketplaces, but there's nothing currently for sale.

If I can't manage to get everything working, I could recode the control panel to work with the windshield heating system and operate the auxiliary heater using the original remote control. I already have that remote, and it should function independently.

Or I could intercept the signal from the rear window heater and send it to the windshield... Back in 2015, I already did something similar for an Android navigation system to turn on and adjust the volume of the original sound system. At that time, I even built the hardware myself and hid it behind the glove compartment. Are there any ready-made solutions available now that can perform such tasks?

Best regards,
Christian.

Hello everyone,

"I finally found some time today and wanted to install the wiring harness. After removing the battery and the electrical box, I wasn't sure where to mount the included relay holder... As far as I can tell, the original relay should be located next to the glow plug relay."

I contacted Kufatec and I'm looking forward to seeing what they have to say. I've attached a few photos below; maybe someone has an idea.

Best regards,
Christian.

Hello Christian,


It's just as you suspected.

The relay for the windshield (J47) is mounted next to the glow plug control unit (J179) in the free space within the electrical box.

Best regards,

Michael.

Hello Michael,

Yesterday I was still looking through the parts lists, and it looks like I need relay 3B0 951 253, socket 3C0 973 721, contact terminals, and screw N 907 676 02.

The Kufatec wiring harness looks completely different; it has a relay bracket for 3 relays, which can only be mounted somewhere that is dry and dust-proof. However, the wiring harness itself seems to have been put together with some thought, so I suspect either it's intended for a different car or it will be installed somewhere else. I'll keep you updated.

Best regards,
Christian.

Good morning, Christian.

Did you receive a wiring diagram from Kufatec?

According to the manufacturer's specifications, the relay should be located inside the electrical box.

If you install it inside the BNS unit, the cable runs will be shorter.

The terminals should be connected as follows:

85 - to the BNS T52b/23 rt/sw 0.5

86 - to the voltage stabilizer (J532) located under the seat at T12o/7.
DC 2.5 rt/bl

87 - goes to the windshield.

30 - connects to the fuse holder SB28 (50A fuse) T40a/4 rt/gr 6.0.


What did you get? Is there an instruction manual for it on the Kufatec website? Maybe you could take a picture of the installation kit.

Best regards,

Michael.

Hello Michael,

I purchased the wiring harness kit 47633 7L3. There is also a variant 7L6 available. A wiring diagram is not provided, but there is an instruction manual.

"There, it says I should attach the relay holder to the electrical box in the engine compartment. The electrical box contains all the fuses, and I haven't found a place where I can clip the relay holder into place. I can't imagine that it means I should just put it inside the electrical box and secure it with cable ties or something similar. Especially because there's an original relay holder underneath the electrical box that has space for a relay..."
Furthermore, the cables for SB28, SB8, and T52B are approximately 1.5 meters long and are bundled together.

Looking at the wiring harness as it is now, I would guess that the idea was to mount the relay somewhere in the engine compartment on the driver's side. From there, two wires would run to the window, and the three bundled wires would be routed into the driver's footwell and connected to the control unit and fuse box. However, this is completely different from the original setup...
Underneath my driver's seat is the amplifier for the original sound system. I don't have an automatic start-stop function.

I'm curious to see what response I get from Kufatec.

Best regards,
Christian.

While looking up the original part numbers, I also noticed something else: In the original wiring diagram, a 6mm² cable is specified for the main supply line, while 2.5mm² cables are used to connect to the individual components. In my wiring harness, all of these wires have the same thickness, and they are likely 2.5mm² in cross-section.

Okay, I'm starting a list of the original parts here. The following is what I think I need, but I'm not sure about the plugs and connectors.

3B0 951 253 - Relay
3C0 973 721 - Relay module.
357 972 742 - Inserts for 0.5 mm² cables.
257 972 742 B - Inserts for 2.5 mm² cables.
257 972 742 C - Inserts for 6mm² cables.
071 973 851 - Steckergehäuse f. Disc.

4.8mm Flachstecker Crimp-Kontakt f. Disc.
4.8mm crimp contacts for 0.5mm² wire.
T52B/23 crimp contact for 0.5mm² wire.
9.5mm crimp contacts for 6mm² cables.

Cable 6mm².
Cable 2.5mm².
Cable 0.5mm².

I got the part numbers from the internet. Is there a trick in Erwin (siehe Fehlerdatenbank) to easily access the spare part numbers? If so, I'll take another hour and try to find them.

Best regards,
Christian.

Hello everyone,

I've made significant progress with my windshield defroster project.

As I mentioned before, the wiring harness from Kufatec was nothing short of terrible. They "investigated" the issue for 5 weeks and then informed me that they were revising the wiring harness. So, with a bit of luck, future customers will receive a suitable set.

In the meantime, I managed to source all the necessary parts myself and installed everything. I left the two cables that connect to the windshield long so that the technicians can cut them to the correct length and crimp on the connectors when they replace the windshield.

On Thursday, the window was finally installed. Today, I programmed the window into the vehicle's control unit and installed a control panel with a button for the defroster. So far, everything is working well; the window is heating up.

However, a few questions still remain for me.

The device draws approximately 50 amps. It is also protected by a 50-amp fuse. Naturally, the fuse gets quite hot. Does anyone have any experience with this? Are there perhaps special maxi fuses with lower voltage drop? Otherwise, I might consider switching to a 60-amp fuse.

Ich hab ja jetzt keine Standheizungstaste mehr. Ich kann die Standheizung aber mit der Fernbedienung einschalten. Allerdings ist das dem Klima Bedienteil egal und es schaltet die Lüfter nicht ein. Kann ich ihm das irgendwie beibringen? Ich habe mal kurz durch den Codierungsassistenten geschaut aber nichts offensichtliches gefunden. Sobald ich dazukomme werde ich alle Fehler löschen und einen aktuellen Autoscan posten. Currently, the control panel still displays error messages from the old car.

Best regards,
Christian.

Address 08: Climate Control/Heating (J255)
Label file: | DRV\5K0-907-044.clb
Part number SW: 3T0 907 044 CJ, HW: 3T0 907 044 CJ.
Component: Climatronic
Part number: H19 0709
Revision: 00001009
Encoding: 0010000003
Operating number: WSC 33361 790 00999
ASAM Dataset: EV_Climatronic A01010
ROD: EV_ClimaAutoBasis_SK35.rod
VCID: 7CF05B27F78A426F90-8028

Attached is the scan with the new control panel.