1. A method for establishing a wireless network for a vehicle, the vehicle comprising a tractor unit and a trailer, the tractor unit comprising at least one first station and a first control unit with the first control unit assigned to and in communication with the first station, and the trailer comprising a second station and a second control unit with the second control unit assigned to and in communication with the second station, the method comprising:supplying electrical energy to the second control unit;
interconnecting the first control unit and the second control unit via a physical interface between the tractor unit and the trailer;
in response to the electrical energy being received at the second control unit, generating a defined message by the second control unit for transmission via the physical interface;
receiving the defined message by the first control unit via the physical interface;
transmitting a wireless signal containing information required to establish the wireless network via the first station only after the defined message is received by the first control unit and is present in the first station; and
establishing the wireless network between the first station and the second station for connection to an external device,
wherein the second control unit is a brake control unit, and wherein the first station transmits the information required to establish the wireless network only when a CAN message with the designation EBC1 is present in the first station and a first bit of the Trailer ABS Status contained in the message has the value 0.