Canister Purge Solenoid: Description and Operation

The ECM controlled canister purge vacuum switching valve (VSV) is in the vacuum line to the purge control valve. Normally closed, the VSV opens when energized by the ECM. During idle or cold operation, the VSV is closed (de-energized), preventing canister purging. To maintain proper air/fuel ratio, the ECM energizes the VSV to permit canister purge based on inputs from the coolant temperature sensor, throttle position sensor and vehicle speed sensor.