Find a workshop manual for your car and it will be drawn inside it. Because car is more-less a faraday cage, there are coax cables [0] going from ECUs to antenn

Find a workshop manual for your car and it will be drawn inside it. Because car is more-less a faraday cage, there are coax cables [0] going from ECUs to antennas. Some ECUs, like eCall have also backup GSM antenna integrated, but you will see the PCB antenna just next to GSM / GPS connector. On VAG cars it is usually easy to remove as well. https://www.carsystems.eu/vw-audi-gsm-fakra-extension-cable-5-5m-triplex-antenna,id1755.html https://www.carsystems.eu/vw-audi-gsm-fakra-extension-cable-...