| Modern automobile electronic control system is more and more complex, thetraditional automotive fault diagnostic techniques rely on manual experience indisassembly operation and repairing parts. However, this method is not feasible forthe car has many electronic components. Modern fault diagnosis using high-techequipment, make scientific and accurate judgments about fault. Greatly improves thereliability of vehicle maintenance and faster maintenance. With the rapid developmentof automobile electronic technology, in order to find the vehicle fault code, almost allof the vehicle control systems, increase the self-diagnosis function. The use ofspecialized fault diagnosis system, the vehicle maintenance and repair personnel canquickly grasp the cause of the malfunction of the vehicle stored in the ECU.Automotive fault diagnosis technology has become a major issue of the current study,and has a very important scientific significance and practical value.Handheld fault diagnostic equipment supplied by the traditional automotivesupplier, there is poor universality, extremely inconvenient and expensive and so onshortcomings, this paper analyzes the development status of automotive diagnostictechnology at home and abroad, combine the vehicle communication interfaceequipment, design PC automotive fault diagnosis software system, achieve the cardata stream analysis and fault code analysis to help automotive maintenance personnelto troubleshoot. PC automotive fault diagnosis system can effectively solve theproblem of the traditional hand-held diagnostic device. The key technology ofautomotive fault diagnosis system is diagnostic protocols, including CAN bus andKWP2000protocols. Authoring Tool (the diagnostic data entry system) entry requireddata using automotive diagnosis. Hardware devices use VCI, the vehicle communication interface equipment. VCI that Pass-Thru+XS2G, fully taking intoaccount the J2534and J2534-1standard, finally implement a PC-based automotivefault diagnosis system based on this basis.Main research work and content in this paper are as follows:Firstly, introduce the research background of the automobile fault diagnosissystem, discuss the development of the automobile electronic technology, and thenlead to vehicle bus development, finally discusses the development of the automobilefault diagnosis technology at home and abroad.Paper makes a more comprehensive and in-depth research for the automotivediagnosis theoretical knowledge, cutting-edge technology and the key technology ofsystem development. Automotive fault diagnosis protocol is based on the CAN busand KWP2000protocol, comparison and analysis on the CAN line and K-lineprotocol, all automotive electronic control unit communications follow protocolstandards, there may be the suppliers of the electronic control unit module to modifythe standard diagnostic protocol to adapt its own module communication standards.Discuss requirements analysis and design of automotive fault diagnosis system.MVC three-tier architecture leads to the three-tier structure of the PC automotive faultdiagnosis system, divide diagnosis system into several functional modules based onrequirements analysis, functional modules including the vehicle identification module,diagnostic module, programming and coding module, data management module andfast channel module, give the design of the fault diagnostic system, including systemworking principle, system application platform requirements and non-functionalrequirements, provide a strong theoretical support for the follow-up work.Paper completes PC-based automotive fault diagnosis system and presents maininterface design of the system and function implementation. Describe a real-timedisplay module for the analysis of the data stream and the fault code. The securityauthentication algorithm is used to establish sound security mechanisms. This articlefocuses on the ECU refresh module, including the ECU communication process, therefresh file parser, ECU refresh algorithm, the concrete realization of the refresh class,EMS refresh rate to improve the program, the authorization mechanism algorithmimproved and the problems and solutions encountered in system implementationprocess.The diagnostic system tests include simulation testing, bench testing and vehicletesting, test results show that the new car fault diagnosis system realizes data flowanalysis and fault code, the system is operating normally, and be able to meet the actual requirements.Finally, make a brief summary about the automotive fault diagnosis system ofspecific studies and innovative works in design and implementation process, and pointout that the system will need to improve.Automotive fault diagnosis system based on Pass-Thru, with high reliability,easy to carry, low cost and functional advantages such as easy to expand, diagnosticsystem has been functionally verified in the real car. The test results show that thenew car fault diagnosis system has a high diagnostic performance and the ability toadapt to the type of vehicle, read out diagnostic fault code information stored in theelectronic control unit, and analyses the data stream, through the analysis of thedeviation from the direction and size of the standard data to indicate the cause of thefailure. But there are still many deficiencies, such as remote diagnostics, informationand data online, Telematis services and digital plant and so on, these are expected infuture research to achieve and optimize.The system from the theory and practical application has a strong advanced andpractical, the system has been put into the market, can be used in a large number ofmodels. The automotive fault diagnosis system can replace existing fault diagnosticproducts at home and abroad, has a high value in use and research value, providing aneffective solution for the development of similar products. |
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