I. Introduction
In recent years, the development of China's economy has promoted the development of the automobile industry. There are more and more automobiles in the city, and the security problems that follow have become increasingly prominent. Among the factors affecting automobile safety, braking performance plays a decisive role[1]. Studying the defects and failure modes of the automobile brake system not only helps the defective automobile product recalling authority to define the defect identification and classification, but also can improve the quality management level of the automobile brake system parts and components, and promote the post-market of the automobile industry in China. At present, the research on the defects of automobile brake system mainly focuses on: Li Zhanfeng analyzes and improves the long braking reaction time during the running of the WC5J explosion-proof diesel engine trackless rubber tire used in underground coal driving[2]. Chen Chen improved the stability of the unit operation by analyzing, researching and improving the defects of the mechanical brake system of Xianyou Pumped Storage Power Station[3]. The above research on brake system failures and defects lies in the diagnosis and resolution of a specific defect problem, and there is no statistical study on other possible defects of the brake system. Li Juanjuan et al. studied the status of state monitoring and fault diagnosis research of hoist brake system in China[4]. Xiang Yongjian studied the fault diagnosis of the brake system in the automobile and proposed a series of improvement measures[5]. The above research on the failure and defects of the brake system lies in the diagnosis of the fault, and does not summarize the classification of the types of defects. Chen Yuzhong analyzed the defect modes and defects of the motor in the ABS of the automobile, and improved the FMECA by the fuzzy comprehensive evaluation method[6]. Lu Ning et al analyzed the situation of recalls caused by defects in automobile brake system in recent years. Based on the risk level, a risk assessment procedure for automobile brake system defects was proposed[7] Yin, Yan et al. detailed the defect status of power assist devices, electronic control devices, sensors, hydraulic components and mechanical parts by analyzing the safety performance requirements of Chinese and American automotive brake systems[8]. The above research on the failure and defects of the brake system lies in the risk assessment and defect state assessment of each defective component, and the fault mode of the defect is not classified and analyzed.