十一月 26th, 2009 20:38
keyword: auto sensor control computer system failure since confirmed the diagnosis: 1, time-domain method to determine when control of a computer testing found the input signal to a certain period of time has not changed or not changes in the pre-requisite number of times, since Diagnostic system to determine the signal failure. For example: oxygen sensor in the engine to reach normal operating temperature, into the closed-loop control system, the computer can not detect oxygen sensor output signals over a certain period of time or oxygen sensor signals 0.45V up and down in the situation has not changed over a certain period of time, self-diagnosis system To determine the oxygen sensor signal system fails. 2, vehicle maintenance network for the conservation, range method to determine when the receiving computer to control the input signal beyond the prescribed range of values, self-diagnostic system to confirm the input signal failure. For example: a car designed temperature sensors used in the normal temperature range -30-120 ℃ (or something larger), the output voltage of 0.30-4.70V, when control of the computer detected signal voltage is less than 0.15V 4.85v or more to determine when the water temperature sensor signal system short-circuit or open circuit failure. 3, functional method to determine when a computer to control the actuator movement issued a directive, the corresponding sensors detect changes in the parameters of the output, if the sensor output signal failed to follow the procedures provided for changes in the parameters, or to confirm implementation of the circuit failure. For example: General Motors EGR system with a high degree of EGR valve sensor to detect EGR valve is working correctly. However, some car did not set a high degree of EGR valve sensors, computer control of when to issue an order to open EGR valve, by detecting air pressure MAP sensor output signal whether there is a corresponding change, but also to determine whether the EGR valve action, if there is no change, EGR valve circuit and confirmed that there are failures. 4, the logical method to determine control of a computer with two interrelated sensor data comparison, when the discovery of the two sensor signals the logical relationship between the violation of the conditions set, it must be concluded that his fault. For example: control of the computer detects a speed greater than the engine speed, throttle position sensor output signal is less than a certain value, to determine throttle position sensor failure.