With the wide application of electronically controlled technology in automobiles, modern automobiles have become a relatively complicated integrated control system of machine, electricity and liquid. Because of the variety and number of various sensors and actuators, the circuit of the automobile is very complex, so the higher requirements for fault diagnosis and maintenance of the automotive electronic control system are put forward. In addition to the functions of ECCS, EAT, ABS, and so on, the electronic control system has the function of fault self diagnosis. It greatly simplifies the troublesome diagnosis process, and makes the fault diagnosis and maintenance of the electronic control system fast and convenient, and provides a gold key for modern automobile maintenance.