Vacuum Line Control Solenoid Valve

Using an ohmmeter, check resistance between terminals of solenoid. If resistance is not 33-40 ohms, replace solenoid valve.
Using an ohmmeter, ensure windings are not grounded. Apply battery voltage to valve terminals. Ensure passage opens and closes as voltage is applied and removed.
When solenoid is not energized, passage between "A" and "B" should be closed and open between "B" and "C". See Fig 1 . When solenoid is energized, passage between "A" and "B" should be open and closed between "B" and "C". If solenoid valve does not operate properly, replace solenoid valve.

Fig 1: Testing Vacuum Line Control Solenoid Valve
Courtesy of SUBARU AMERICA, INC.