Updating TPMS to RDKS (7K9 → 7K3) or "suprises in an easy retrofit"

Yesterday I (almost) realised an idea I had back in August 2019. Why almost? Don't be impatient and read the whole story…

The birth of the idea
My car form the factory came with flat tire indicator (PrNo: 7K9)
It was back in August when after exiting a super market I loaded the car with bags and entered the car as usual. I drove 50 meters or more and got the warning message "Loss of pressure: front-right tyre". To cut the long story short, due to driving a few meters the tyre was damaged and I was advised by the tyre expert to replace it. It was then when I thought that if I was warned earlier by the car I would never drive and destroy the tyre.

Questions started appearing in my head:
* How can I be warned earlier than having a flat tire? RDKS offers what I want: it warns the driver for any signficant pressure loss
* Is it expensive to buy? Well, according to Drive2 members who did it, not really expensive.
* Is it easy to install and code? Again, according to Drive2 members who did it, it is one of the easiest retrofits ever.
Apart from these, there was an additional bonus: a pressure drop warning is safer than a flat tyre warning during travelling fast on a highway…So the decision was made with certainty: I needed to have RDKS retrofitted.

Materials
First I ordered wiring from Aliexpress for 21.49€. The wiring came and immediately had the first surprise when I checked their position on the connector: the CAN wires were reversed. Instead of the CAN extended High to be in pin #3 it was placed by the Chinese in Pin #1. Instead of the CAN extended Low to be in pin #1 it was placed by the in Pin #3. No big issue as it can be solved easily but nevertheless it was good that I checked.

Second order was the antenna (Part number 5Q0 907 273 B). Instead of ordering from China, I asked VagSerp for help. He was professional, fast in asnwering and has good skills in english language. We arranged for the price of antenna and uploading the necessary pressure dataset to it (at that time I did not have ODIS and VAS5054A which I bought later).

So started the quest for data. My car has 16" alloys and as I wanted to include pressure data for 15", 16" and 17" I had to ask people with 1.6 TDI engines (CLHA) about the sticker on their fuel doors. I am grateful to humaxor for his photo of his fuel door sticker that corresponded to his factory 15" alloys. I am also grateful to Danylyukm for his info that corresponded to his factory 17" alloys. As it was proven the same pressure is required for 15", 16" and 17" in 1.6 TDI. This is:

* 2.2 (front) — 2.2 (rear) for standard load and
* 2.4 (front) — 2.8 (rear) for full load

These pressures apply even in 1.4 TSI engines (thanks kayle for his 16" data and karras88 for his 17" data).

As in MQB a third load option called "comfort" is needed to be coded, I asked Mikhail to put in "comfort" the same values as in "standard" load.

So everything was ready and I knew that ordering outside the European Union would mean possible import taxes but I relied on the fact that greek customs officers would not care for a small package. Of course life teaches us lessons when we have high expectations…The greek customs officers detained the package and asked me to prove its price by sending the necessary documents to them. So I did l, and the package was released from customs and transfered to the post office of my city. When I went there to pick it up, life gave me the second surprise: post office officials are very organized…To pick up the package VagSerp sent me they wanted me to pay taxes that correspond to a much higher price than I paid for…Why? They probably thought that me and Mikhail were lying to them, and so they calculated the taxes according to the antenna's "statistical price" for which probably they searched on the internet…The "statistical price" was 108.30€ and the corresponding taxes for this price were 40.99€!

Last parts I had to order were the sensors (Part number 5Q0 907 275 B). In Aliexpress the price was good but, adding the high possibility of paying again extra taxes, the price would be equal to ordering from an eBay store in Slovakia which is member of the EU. The sensors at that time (August 2019) were quite fresh (production date: January 7th, 2019) and their price was 70€.

Installation & coding
Nothing new here. Installation steps have been well documented by various people inside this forum. Connection was made to (Terminal 30) SC15 with a 10A fuse. The wiring proved to be very long. It passed from the driver's side under the rear seats to the rear wheel well (where the back of the fuel door is). While passing under the seats I used a plastic flexible tube for protection purposes.

The position of the antenna was between the rear right wheel well and the bumper.

I stucked it there with Dual Lock VHB adhesive tape in a vertical position (this proved to be wrong as I found later).

Coding was easy and details can be found in numerous places. One of the most well documented is found here

As this is considered as a very easy retrofit I expected everything to go on smoothly. But no. I had to face a third surprise…There was an issue noone before has written that he faced it: in VCDS the dashboard module showed the error "Incorrect software version"

Additionally, no matter how long I drove there was no data sent to 5F module. Furthermore the car on the MIB screen was always dark grey and on full load the rear wheels were showing the value 2.4 instead of 2.8 bars.

After connecting VCDS things got more complicated: it is clear that the sensors communicate with the antenna and send their pressure data which is not transmitted to the Discover Media display.

After exchanging numerous messages with VAGSerp the culprit was found: wrong position of the antenna that prohibited the sensor position determination. The antenna should be positioned on an axis perpendicular to the movement of the car ( if you remember I placed it vertically) to work properly. Thank you Mikhail for your tips!

So once more I removed some plastics and the carpet and changed placement direction of the antenna. Then, started driving and after approximately 500 meters the car icon on the Discover Media display became white and the pressures were displayed correctly!

Happy for the new functionality I switched off the engine and took photos:

Now VCDS scan shows only one error (the usual error about incorrect software version)

Issues that remain are 2:
* I have no MFA menu for pressure data
* When a warning is issued because of low pressure I do not get pressure numbers on the MFA. Instead I get only zeros. The correct numbers I get them only on the MIB display.

For the dashboard error maybe the solution is to finally change to Active Info Display :-) :-)

Having recently obtained ODIS-E I modified the stored pressures and created a dataset that suits better my needs. Instead of having the same values for "Comfort" and "Standard" I used the lowest pressure that Continental suggests for its tyres on my car (see page 218 of the PDF). So my final pressure table is this:

As Continental suggests (see page 2 of the PDF) the "Full load" values should be used for motorway driving. So don't forget to inflate the tyres to full when driving on motorways

Bonus
As the plastics at the trunk and the rear wheel well were removed I finally replaced my fuel door lock which failed around 14500 km ago. Please don't judge me :-)