The Design Of Vehicle Remote Fault Diagnosis Svstem Based On OBD-â…¡

China has developed motor vehicle emission regulations to limit the emissions of vehicle pollutants. Make requirements for cars to equip with OBD-II system which can monitor vehicle emission systems and related components. When the failure vehicle may cause higher air pollutions, OBD-II can light up the car malfunction indicator (MIL) and generates a fault code. But OBD-II only light on the MIL and can’t stop the vehicle with high emission working on the road. The drivers with poor consciousness will still drive the fault vehicle without management until the yearly inspection. This will pollute the environment very much.So a kind of vehicle remote fault diagnosis system based on OBD-II has been supplied. Use vehicle fault diagnostic test terminal to send the location and breakdown messages to the remote software system by3G network when there is the fault in the emission control system. The remote system installed on the sever diagnosis the reason of the vehicle fault and give the recommendations. Display the location of the fault car on the digital Google Map. Help the regulatory authorities to notify the drivers to repair their vehicles in a limited period and improve the supervision. The design includes hardware and software design of the vehicle fault detection terminal and remote fault diagnosis software prototype system. Solve the problems such as fault information collection and transmission, remote diagnostics and display problems.The fault detection terminal can read and transmit the fault information. Use STM32F103controller and TL718chipset to read the data byte from the OBD data bus which can be compatible with KWP2000and ISO15765protocol. When the MIL lights up, the terminal will get the information of DTC, VIN, speed, location and transmit it to the remote diagnosis system by GPS and3G communication module.Remote fault diagnosis system can monitor and manage the vehicle with high emission. Use SOCKET communication to receive information sends back by the vehicle terminal. Use database technology to improve knowledge indication by the fuzzy methods and inference engine to establish the fault diagnosis expert system. Use the API functions of GoogleMAP to develop WebGIS displaying which can monitor the vehicle location and display the results of fault diagnosis.Finally, testing and validation programs of the system have been done by fault simulation. Use laptop computer connect USBCAN transceiver as ECU to communicate with the detection terminal by CAN bus. Simulate the fault diagnosis data which follows the fault diagnostic communication protocols to verify the system functions. Experiments show that the simulated data can be detected by the TL718circuit and the fault code can be read correctly. The system can display the conclusion of the fault diagnosis expert system and the geographic location of the terminal. The system can be achieved on monitoring and management of the vehicle with high emission.