The PCM monitors the Fuel Tank Pressure sensor in order to determine the level of vacuum/pressure in the EVAP system. The PCM commands both the EVAP PCSV and the EVAP CCV ON when the conditions are met in order to apply an engine vacuum to the EVAP system. The PCM commands the EVAP PCSV OFF once the system has reached a predetermined level of vacuum. This test verifies if a vacuum can be achieved in the EVAP system. Failure to develop a vacuum may be caused by a large leak or a restriction.