Canister Purge Solenoid: Description and Operation

Charcoal Canister:

PCM Wiring:

The PCM/ECM operates a pulse width modulated solenoid valve which controls vacuum to the purge valve in the charcoal canister. Under cold engine or idle conditions, the solenoid is de-energized by the PCM/ECM, which closes the solenoid and blocks vacuum to the canister purge valve.

The canister is commanded by the PCM/ECM to purge when:

1. Coolant is above 80°C.
2. Closed loop has been achieved for at least 30 seconds.
3. The throttle switch is open.
4. Vehicle speed greater than 10 m.p.h..
5. Engine speed (RPM) above a threshold.

If the solenoid is closed, (not receiving power or has a stuck plunger), the canister will not purge to the intake manifold. This will prevent the canister from purging fuel vapors and could result in a complaint of fuel odors coming from the engine compartment.

The fuel evaporative canister solenoid is part of the evaporative cannister and must be replaced as a unit.