WFS Activation Code: What is it?

Hello,

According to the data from my AI, I have a WFS with a changing code.

How does that work?

Is the transponder in the key recoded by the car after each reading?

Is the transponder re-encoded by the vehicle after each reading?

Something like that; the code that is sent is always different, following a specific algorithm.

Theresias wrote:

It's similar to this, but the code that is sent is always different according to a specific algorithm.

So, the transponder has stored multiple codes (how many exactly?), and each query automatically switches to the next code?

Does the engine computer sometimes read code 1 and sometimes code 5?

Before I mess it up by trying to explain it in my own words:

Page 4 of:
http://www.verkehrsunfallforensik.de/pdf/68_Wegfahrsperren.pdf

Regards,
Sure, here's the translation:

"Guste" is a German word that means "gust" or "gust of wind." It can also be used to describe a sudden burst of something, such as laughter or anger.

In addition to the fixed code, the engine control unit sends a rolling code to the transponder in the vehicle key.

Upon ignition, the transponder sends a fixed code to the engine control unit (ECU) for anti-theft. If this code is correct, the ECU generates a random 'rolling code.' This rolling code is then transmitted to the transponder in the vehicle key. Subsequently, a secret calculation process is initiated simultaneously in the transponder and the ECU for anti-theft.

'In case of the same result, the correct vehicle key is identified. Subsequently, as before, a change code is exchanged between the immobilizer control unit and the engine control unit.'
If this is also confirmed, the vehicle is ready for operation.

Theresias wrote:

Now, a secret calculation process is started in the transponder and in the immobilizer control unit. When the results are the same, the correct vehicle key is identified.

Okay, so the transponder is no longer just a simple device that, after each activation, simply says something like "15," but it can also "intelligently" communicate with the WFS control unit.

It's remarkable that the entire amount of energy required to trigger the process can still be transmitted via a current pulse in the reading coil.

Thank you for your answers .

'This thing doesn't actually need that much energy... and with a coil like that, you can transmit quite a lot.'

The key sender also has a change code, but it uses a fixed table.


Here's the init (always the same for syncing):

http://www.ralfhandel.de/images/TEK00000.BMP

And here are the data readings. The top section shows the readings from the first print, and the bottom section shows the readings from the second print. These values change with every button press.

http://www.ralfhandel.de/images/TEK00001.BMP


CU Gremlin.