Method for data exchange between tractor and trailer

A functional contact operates through transmitter/receiver modules in a pulling vehicle (1) and a trailer (2). To recognize a relationship between the pulling vehicle and its trailer, the transmitter/receiver module (5) in the pulling vehicle transmits an ID signal via an antenna (7) to change the electrical status of a connecting wire (10). If the transmitter/receiver (6) in the trailer recognizes this change along with a received ID, it stores the received ID.