I have a tec-tus 1 immobilizer, mounted later in my Landcruiser in Germany, possibly from the last century.
It has a sensor with a red LED. It reads ordinary RFID-fobs; I have actually tried putting the cat with its ID-chip-implant to the sensor, and it reads something is there. However, for practical reason I have not added the cat to the known fobs ;-)
I now need to add another fob, but I have lost the manual, and forgotten how.