# Webasto interface and WTT software aka vag kkl 409.1



## kicku (Apr 8, 2018)

Hello,

after i did found my webasto unit falling in parts, i've searched around local dismantlers and found a few webasto units. Took 2 units for hack them, or better say, understanding how these units are operating.
The next step was to find a webasto interface, for resoft the unit, test directly on the car or outside.
Spent almost 60€ on ebay for interface with software WTT V3.4
Out of the box, the interface seems an ELM327 OBD interface with 3 wires glued alltogether...but...



But...IT'S NOT.
So, after opening it, found inside the CH340T which is a USB to serial chip, and a LM339 which is quad operational amplifier...
Both of them costs not more than 1-2€, nothing to soft, nothing to write...just soldering and plug & play.
After watching inside the pcb and doing a google with ch340 lm339 serial...the results lead to this:



Well, was not a surprise to me, to see that the interface in fact it is a VAG KKL 409.1 interface.

This is what i've found inside the interface:







As you can see, the resistors have the same values, less on the capacitors (because the values on these are missing), but anyway on the USB side all of them won't change, are always the same, i think these values can be obtained also from CH340T datasheet.
I can say this interface IS IT a VAG KKL409.1
As you can immagine, will cost less to buy one unit already builded than build it one from nothing. On ebay you can get one of these just for 6€.

On the supplied cd with software, there is also a KKL interface which indicate +Positive and -Negative wires and the the Data wire.
The data wire ( green below ), on the interface, it's soldered to the pin 14 and 11 of the CI LM339. This is the KKL1 data wire, on the OBD plug connected to the PIN 7.

So, on a VAG KKL interface, connect the data wire to the OBD plug at PIN 7, Ground - the black wire to the PIN 4 - this will be the - Negative supply and the red wire to the PIN 16 to +Positive Supply 12Vcc.

Will come out something like this...



Now, the software.
On the cd, did found a few folders. Some folders were with drivers for both 32/64 bit systems. Supported systems are XP, WIN7, WIN8 and WIN10 with instructions for install drivers. As you can immagine, the drivers are for CH340 USB to serial chip.

Another folder contains pdf files with instructions on how to install the software and finally another folder with software itself WTT V3.4 and a dependence Diagnosis Framework V1.5

My goal is to modify different webasto units (other than the version mounted on my Phaeton ), to fully integrate into the car as it should be.
My time is less and less between different projects, i am actually working and cannot follow all of them, so whoever wants to take up the challenge and publish the results here, is wellcome.

Here is the magnet ( for utorrent or anyelse torrent software ) with everything found on cd, and in the end the .torrent file which will lead to the same torrent.

magnet:?xt=urn:btih:C14686EEB8FC13B...unce&tr=udp://exodus.desync.com:6969/announce

or the .torrent file:

https://gofile.io/?c=VksXrK

Good work!


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