| As one of the most important parts of the engine electric control system, Fault diagnosis module guaranteed the stability and reliability of vehicle in the course of running. The various electronic components were used widely in the high-pressure common rail system, which improved the power performance and fuel economy of engine, however increased the complexity of the engine maintenance and troubleshooting simultaneously. If one part of electronic control system went wrong and the malfunction was not informed to driver to take effective measures, the emission of engine would rise. Therefore, the diagnostic communication of electronic control system has become critical particularly. Automotive bus protocol is the core of automotive diagnostic technology. KWP2000 protocol (ISO 14230) based on K-line is used more often than other vehicle bus communication protocols.This paper adopted the ISO 14230 automotive communication protocol to design fault diagnostic communication system of high pressure common rail diesel engine. This system made the engine as controlled object and associated the detection device and control unit with communication technology. The software part of fault diagnosis communication system was designed by analysed the ISO 14230 technical specifications. The work of software part included the sum check and the separation handling of message received, the response to initialization commands that is the return of keywords, the extraction of corresponding fault message or ECU data from error memory depending on the message request service, the receiving of message request information and sending of response information.The fault diagnostic communication system of high pressure common rail diesel engine was developed according to modular control strategy based on the ASCET software development platform of ETAS Inc. The expecting targets of collecting fault information, restructuring and writing standard message were achieved through the simulation of communication system. |
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