Retrofit heated seat

[flashmandv]

Hello guys,

I started ambitious project of retrofitting heating seats (front ones) to my A6 C7 4G.
I bought the right climate panel (with the heating seat buttons) and some universal heating pads (with temp sensor and level slider). I'm currently waiting for kufatec wiring harness.
I'll also get the new climate panel's component protection removed in Audi dealership in Tuesday.

However I don't know how and where to connect the heating pads and the temperature sensor.
Can somebody help me with wiring advice?

Do I need to replace one of the existing 3 wiring cables that connect to the climate panel? Or just add some pins for connecting the pads and the sensor?

I have audi service manual for my car (the huge pdfs) but I can't seem to get decent info on this.

all.jpg climatepanels.jpg climatepanels_rear.jpg wiring.jpg

Thank you

[Ste1981]

,

[morski]

The heating mats dont connect to the panel at all. When you select seat heating on the panel it sends a message via the LIN bus to the PSM or BCM what ever you want to cal it mounted under the dash. That then switches on the heater mats via the heavy duty cabling connected directly to it.
Using after market mats may or may not work. You will need to study the oem diagrams and compare wire for wire and if its doable then connect the mats wires to the correct pins in the PSM. VCDS coding will also need to be done in order to tell the car you have the heated seats
Personally i would have stuck with the genuine ones. Less hassle or should say slightly less!

[Fakie1977]

Nightmare job doing it that way you will have to strip the seats and refit won't be easy would of been easier getting some heated leather seats out of a scraper like I did on my golf then it was a matter of just fitting the kufatec harness. Bear in mind over here I could only get a left hand drive one so had to cut both connectors of and swop them over and solder extra length of wire on so it fit bear in mind all the wires was grey 3 into fuse box 3 to control panel 1 to the cecm 1 earth to body then run the connectors under both seats

So I’m about to do the same and fit the kufatec wiring loom to heated seats. Would it not have been easier cutting and extending the fuse cable wire so to run it from the passenger side up and around the dash towards the RHD drivers side fuse box? Less wires to cut and extend I assume than chopping the 2 connectors. Or am I missing something?


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[flashmandv]

The heating mats dont connect to the panel at all. When you select seat heating on the panel it sends a message via the LIN bus to the PSM or BCM what ever you want to cal it mounted under the dash. That then switches on the heater mats via the heavy duty cabling connected directly to it.

@morski So "heavy duty cabling" is a new wires that need to be placed from the PSM/BCM to the heating pads? (And basically strip dash, floor, etc.. ?)

The mats are pretty simple. They get 12V power and that's it (the temp sensor is embedded and it can shut off on its own)

What exactly do I connect with the kufatec cable?

What about the fuse? Do I need to install new fuse on the way of the "heavy duty" cable from PSM to seat?

Thank you all

[flashmandv]

@morski is this the BCM module that is atctually wired to the heated seat? This one is in my trunk (I think they also called it "comfort module")
So kufatec cable connects from here and to the seats?
s-l1600.jpg

[morski]

Nope, thats the BCM2 module as you know from the boot. Nothing to do with the heated seats. The PSM is under the dash by the drivers side literally above the relay holder. The wiring from the heated seat loom will connect to this unit. By heavy duty wiring i mean the correct gauge that is specified in the elsawin wiring diagrams, ie 1.5mm2, 2.0mm2, etc You really need to get an hour subscription from Erwin and study the A6 4G model with the correct year of your car.
You will need to check your PSM i referred to to make sure it has the pins in the unit for it to accept the heated seats.
What year is your car?

[flashmandv]

Thank you @morski.
Just yesterday I made 1hour subscription and downloaded the wiring diagrams for my model. I'm a bit confused as there is another module there: J882 (seating heat module) that looks different from the PSM (BCM1)
I'm not sure if PSM (BCM1) and J882 are the same module. What do you think?
bcm1.jpgJ882.jpglocation.jpgbutton.jpg

EDIT: It seems BCM1 module is J519 in the wiring pdf:
BCM-J519.jpg

[flashmandv]

OK, My kufatec cable arrived and now I have much bigger idea on what is going on.
It has 3 connectors and couple of wires.
bcm1-kufatec.jpg
This kufatec connector I think goes to BCM1 G-slot (the center one). The 3 cables fit perfectly the pins on G slot.
The thickest "steady plus" side cable goes to the fusebox (not sure where..maybe isntall new 30A fuse on the side panel). There is also another thick ground cable.
The other 3 tiny pin cables are labeled GE SM BR and I guess they should go to A,B or C slot on the BCM1 module (but not sure which one and where)
I assume these wires are for the temparature sensors.

On the other side I have two connectors for the seats..but as my seats are not heated, I don't have where to put them on my seats so I guess I'll take the pins out and connect them to the pads.


kufatec-seat-connectors.jpg

I assume the thickest pin3 and pin4 are + and - power supply for the pads.
The tiny pin1 and pin2 are for the temperature senson..which in my case is integrated in my NON OEM pads and I won't use.

Here is how my pads look like:
20190204_140415.jpg

As you can see there is integrated fuse/senson that is some sort of protection.
My pads also have heat regulator that I guess I'll just put to the maximum (level 5) and let the climate panel/bcm1 regulate this.
20190204_135731.jpg

Here is the schematic from the wiring diagrams of my car:
BCM1-J519-pinout-driver.jpg

There are still many mysteries as:
1) How is BCM1 module regulating heat level? By voltage, amperage, or by some of the small wires?
2) Can all this work without the OEM temperature sensor and without having the J882 seat heating control unit?

Thank you for all the help @morski and I hope to hear from you.

[flashmandv]

PROGRESS UPDATE (addon to my monolog):
I've connected the kufatec cable to the proper place in the BCM1 module. I also connected the 3 pins to the big 32 pin connector. Pins are 14 (sensor 1), 19 (sensor 2) and 25 (temp sensors ground)
20190207_124334.jpg20190207_131355.jpg20190207_134537.jpg

I also added the heating seats "extra" in green menu.
My main problem now is this VCDS "function restricted due to Missing Message(s)" error and how to code the new heating seats in 08-HVAC module.
The last problem is what resistor should I add to replace the temperature sensor.If anyone with Audi A6 4G can measure its resistance from the seat connector tiny wires, I would be very thankful.
As per wiring diagrams of my Audi, I have to connect the two heating pads with serial connection (not parallel).
Right now without any resistor or temp sensor I measure constant 12V on the heating pad cables and there is no changes when I press the heating buttons on the climate panel.

Can anybody help me with the coding?