| 摘要 |
PURPOSE: A failure detecting method of a thermostat for a vehicle is provided to reduce repair cost from wrong diagnosis by restricting wrong detection of fault of the thermostat with counting again in releasing fuel cutoff. CONSTITUTION: The fault diagnosis condition of a thermostat for keeping constant coolant temperature by automatically opening and closing the coolant passage according to coolant temperature in the engine is detected(110), and the initial count time is reset according to coolant temperature in starting the engine in satisfying the fault diagnosis condition(120). One step * coefficient from the initial count time is decreased per 500 ms(130), and decision time counting is stopped or performed in cutting off fuel or not(140). The decision subtraction time is adjusted again(150), and remaining time is selected by detecting the corresponding range of the mean air amount in detecting fault diagnosis of the thermostat(160). Coolant temperature is compared with the predetermined value(170), and the decision time is compared with zero(180). The fault of the thermostat is decided in case of decision time to be zero(190).
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