| 摘要 |
PURPOSE: To diagnose the operating condition of a negative pressure switch, besides the operating condition of a solenoid valve. CONSTITUTION: Diagnostic area of the closing side of a solenoid valve is set at Tp<2.0ms that the negative pressure can be certainly secured. At the time of closing control of a solenoid valve, when turn-on of a negative pressure switch is detected, abnormality of a solenoid valve of the like is judged (steps 1→2→4), and when the predetermined time is passed after the solenoid valve is controlled for opening, when the turn-off of the negative switch is detected, abnormality of the negative switch is judged (steps 1→7→8). Furthermore, during the time of non-rotation of an engine, when the pressure inside of a negative pressure lead-in pipe becomes the atmospheric pressure, when the negative switch is turned on, normality is judged, and when the negative switch is turned off, abnormality is judged.
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