| 摘要 |
PURPOSE: A self-diagnosis method for engine speed signal is provided to allow for rapid detection on problems of engine control unit by permitting the engine control unit to self-diagnose its engine speed signal output end. CONSTITUTION: A self-diagnosis method comprises a first step(300 to 303) of integrating switching pulse frequencies from a cam shaft rotational frequency sensor for sensing the rotational frequency of the cam shaft after starting of engine; a second step(304) of integrating number of engine rotational frequency pulses output from an engine speed signal output end of an engine control unit during the integration performed in the first step; and a third step(305 to 308) of calculating the difference between the switching pulse frequencies integrated in the first step and the number of engine rotational frequency pulses integrated in the second step, judging whether the difference is higher than a threshold value, and storing error codes and turning on an engine warning lamp, if it is judged that the difference is higher.
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