Development and Research of Vehicle Fault Diagnosis System

The status of vehicle fault diagnosis protocols applied in the market is analyzed, and also are the problems of the hand-held diagnosis instruments. Through the way of combination of PC-style diagnosis software and Vehicle Communication Interface (VCI), the popular type of vehicle fault diagnosis system based on both K-line and Controller Area Network (CAN) is developed. The diagnosis system is divided into four layers (application layer network layer, data link layer and physical layer) referred to the Open System Interconnection (OSI) network model to develop the KWP2000 protocol stack. In order to enhance the commonality of the system, protocol of application layer is implemented by PC-style diagnosis software, while protocols of network layer data link layer and physical layer are implemented by VCI. While developing PC-style diagnosis software, modular construction method is adopted to facilitate further upgrading and expansion. The test research in real vehicles proves that this system can not only perform well to diagnose the faulted vehicles, but also have the potential for further upgrading.