An automobile connection cable is configured with a controller area network (CAN-bus) circuit design and provided with a protocol interface between the J533 connector and USB Type-C. The function of switching between different protocols is achieved through the configuration of the cable assembly, so that the driver-assistance system ensures a better adaptability to the VAG vehicle models of Volkswagen Corporation (VAG). When the vehicle is shut off, the circuit control board can also control the constant power supply system between the external device and the vehicle, thereby reducing power consumption.