Hi.
First of all, thank you to everyone.
Since the GRA (presumably a device or system) can also implement speed limiters, I had set the corresponding bits in the MSTG (likely a configuration or control module) – and it worked.
The corresponding bit in byte 1 of the steering wheel control module could not be set (error message).
The bit for "horn only when ignition is on" in byte 0, on the other hand, could be set without any problems.
We then stopped the process and reset the MSTG coding to its initial state.
This afternoon, I have an appointment at the

, and hopefully, I will get the activation through the code that came with the conversion kit.
I'm excited and will report back.
Best regards,
Micha