Diagnosis And Analysis Of The Bmw Can Bus Fault

With the progress of information technology, the vehicle electronic control system is becoming more and more complex. Many manufactures use CAN BUS system to exchange data developing on the basis of computer network techniques and the on bus control system. But at the same time the diagnosis and analysis of automobile fault become more complicated, determining the reason becomes more difficult. For the CAN BUS system, a key problem is how to find out the real fault as soon as possible in the many fault information and diagnose out the specific fault components and summarize the law and methods of diagnosing the fault of CAN BUS system. This is a very difficult problem in the process of repair. We should find out the method of diagnosing the fault of CAN BUS system. It is very significant to research the CAN BUS system.First it introduces the CAN BUS system of BMW E90models. This paper mainly introduces the operation principles of CAN BUS system. Then it introduces the relating control units and the control logic on the FRM of BMW E90models that is most associated with other module. Next it measures, analyzes and comprises the waveform of the normal work, short circuit and open circuit of PT-CAN, K-CAN and F-CAN using excluding tools of BMW. The auto repair personnel in the actual work compares the waveforms with the waveforms in this paper, he can quickly find the fault reason and determine the fault point. Finally it diagnoses and excludes the fault of CAN BUS system under the really typical conditions. It analyzes typical failures of CAN BUS system in practical work case, diagnoses and eliminates the faults through combining the test results with the typical actual cases. Finally it sums up the basic ideas and methods of the CAN BUS system fault diagnosis.