Operation

The control module then monitors the ability of the system to maintain the vacuum. If the vacuum remains for a specified period of time, then there are no evaporative leaks, and a pass report is sent to the control module. If there is a leak, the system either will not achieve a vacuum, or a vacuum cannot be maintained. Usually a fault can only be detected after a cold start with a trip of sufficient length and driving conditions to run the needed tests. The enhanced evaporative system diagnostic conducts up to 8 specific sub-tests in order to detect the fault conditions. If the diagnostic fails a sub-test, the control module stores a Diagnostic Trouble Code (DTC) in order to indicate the type of fault detected.