| 摘要 |
PROBLEM TO BE SOLVED: To provide a negative pressure system for surely and precisely detecting failure of a negative pressure sensor, and driving a load by a proper actuation of the negative pressure pump without a pressure sensor for checking the negative pressure sensor. SOLUTION: This negative pressure system of a vehicle comprises a negative pressure sensor detecting a negative pressure on a load side, pump control means for driving the negative pressure pump based on a detected value of the negative pressure sensor, an operating condition sensor detecting an operating condition of an engine, a negative pressure sensor normality judgment means for judging that the negative sensor is normal when a first variation quantity of the detected value of the negative pressure sensor based on a start of the engine exceeds a first threshold, a negative pressure sensor failure judgment means for judging that the negative sensor is out of order when a minimum value of the detected value of the negative pressure sensor is larger than a second threshold, and a failure judgment holding means for holding the judgment that the negative pressure sensor is out of order when the first variation quantity does not exceed the first threshold and the minimum value is smaller than the second threshold. COPYRIGHT: (C)2008,JPO&INPIT
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