Abstract: An automotive vehicle is equipped with an on-board microcomputer having a function of pre-diagnosing and indicating a possibility of arising of an automotive trouble in response to electrical informations relatable to the trouble which informations are stored in a memory device. Additionally, an acoustical coupler is mounted on the vehicle and electrically connected to the memory device to convert the electrical informations to acoustic signals. The thus converted acoustical signals are to be transmitted via a telephone line to a computer for automotive trouble diagnosis purpose which computer is located remote from the vehicle, for example, in the head office of a service firm, thereby making it possible to achieve automotive trouble diagnosis without carrying the memory device to a service factory.