| 摘要 |
A method is provided for determining the rationality of a device for monitoring the pressure within an evaporative emission control system of an automotive vehicle. The method includes opening a valve of the evaporative emission control system and determining if a vacuum switch of the evaporative emission control system opened. If the vacuum switch opened, a code is set indicating that the vacuum switch passed an opening test. If the vacuum switch did not open, the method determines if a fail timer is greater than a first fail threshold value. The first fail threshold value corresponds to an amount of time within which a properly functioning vacuum switch should open after said valve is opened. If the fail timer is greater than the fail threshold value, the method sets a code indicating that the vacuum switch failed the opening test. If the fail timer is less than or equal to the first fail threshold value, the method increments the fail timer. If the vacuum switch passed the opening test, the method closes the valve of the evaporative emission control system and applies a vacuum thereto. The method then determines if the vacuum switch closed due to the vacuum. If the vacuum switch closed, the method sets a code indicating that the vacuum switch passed a closing test. If the vacuum switch did not close, the method determines if the fail timer is greater than a second fail threshold value. The second fail threshold value corresponds to an amount of time within which a properly functioning vacuum switch should close after the vacuum is applied. If the fail timer is greater than the second fail threshold value, the method sets a code indicating that the vacuum switch failed the closing test. If the fail timer is less than or equal to the second fail threshold value, the method increments the fail timer.
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