Canister Purge Valve

Evaporative Emission System:

The Evaporative emission (EVAP) system works in conjunction with the fuel mixture control in such a way that the ECM weakens the mixture when the EVAP system adds fuel to the fuel-air mixture. To handle this interaction, the ECM needs to know the position of the canister purge valve. About 12 V is applied to pin 21 of the ECM when the valve is open and 0 V when the valve is closed.