Abstract
Fault diagnosis is essential for higher productivity by the means of operation safety, efficient repair and fault prevention. The development of automotive systems shows an increasing number of sensors, actuators and microelectronic controllers. In an electronic engine control system, the sensors are the device that receives a stimulus and responds with an electronic signal to microcomputer. On the other side sensors can also be used for fault detection and diagnosis. Most developing diagnostics equipment are systematic testers which take the information from the electronic control unit (ECU) about fault codes. The self-diagnosis system becomes a function of electronic control system, called on-board diagnosis (OBD). The off-board diagnosis instruments receive directly the signal output from sensors via the standardized connection contact to transmit to microprocessor. The signal processing (fault detection, updating database) is then similar to on-board system. The fault detection and fault diagnostic system is built up and presented in this paper. The system is developed by using a programmable microprocessor AT 89s52 (8051 micro-computer), signal processing circuit and decoder circuit interconnected to personal computer (PC). Whenever a fault occurs, the electronic engine control system analyzes the received signals by sensors, detect abnormal function and save the fault code in memory. The diagnosis results can be exploited as data files or graphical presentation on PC. The system is designed as an off-board diagnostic system that can be use for experimental test, repair as well as learning and training purposes.
Keywords: diagnosis, sensor, actuator, electronic control unit, signal, microcomputer, microprocessor