The evaporative emission control system prevents hydrocarbon (HC) vapors from the fuel tank from escaping into the atmosphere where they could form photochemical smog. Gasoline vapors are collected in the charcoal canister. The ECM controls the Purge Control Solenoid Valve (PCSV) to purge any collected vapors from the canister back to the engine for combustion. This valve is actuated by the purge control signal from the ECM and controls fuel vapor flow from the canister to the intake manifold.
ECM sets DTC P0444 if the ECM detects that the PCSV control line is open or short to ground.
Item
Detecting Condition
Possible Cause
DTC Strategy
Circuit continuity check, open
Contact resistance in connections.
Open or Short to ground in power circuit
Open or Short to ground in control circuit
Faulty PCSV
Faulty ECM
Enable Conditions
-
Threshold Value
Disconnected
Diagnostic Time
Continuous
MIL ON Condition
3 driving cycle
Temperature
PCSV Resistance
20?
32?
During normal operation, the PCSV opens and closes, depending on throttle angle and intake manifold vacuum. When it opens, fuel vapors are flushed from the canister and drawn into the intake manifold. To avoid a vacuum build-up in the canister, the canister close valve is normaly held open to alow fresh air to replace the vapors drawn into the intake manifold. The given data is the signal waveform when the PCSV operates normaly. Note that the PCSV will not operate until the engine has reached normal operating temperature.