P0441

CIRCUIT DESCRIPTION
A solenoid valve controls the canister purge. A solenoid valve allows the ported vacuum to purge the canister when energized. The Vehicle Control Module (VCM) supplies a ground to energize the solenoid valve (purge ON). The EVAP purge solenoid control by the VCM is Pulse Width Modulated (PWM) or turned ON and OFF several times a second. The Closed Loop feed back from the Heated Oxygen Sensor (HO2S) determines the duty cycle (a pulse width). The VCM calculates the duty cycle, the VCM commands the output when certain conditions have been met.

A vacuum switch in the purge line detects when the system is being purged. The normally closed switch will open when less than 1 in. Hg is present in the purge line. The VCM supplies a 12 volt reference to the vacuum switch in order to monitor if the evaporative switch emission control system is working properly. If the switch is closed meaning there is nor purge detected when the VCM is commanding a purge, a DTC will set. This DTC is a type B DTC.

CONDITIONS FOR SETTING THE DTC
^ The purge solenoid diagnostic vacuum switch DTC is not set.
^ No IAC DTCs.
^ No MAP DTCs.
^ No TP sensor DTCs.
^ No EGR DTCs.
^ The BARO is greater than 75 kPa.
^ The ECT is less than 110°C.
^ The Power-up IAT is greater than -18°C.
^ The IAT is less than or equal to 90°C.
^ The change in the ECT/IAT is less than or equal to 90°C.
^ The purge DC is greater than or equal to 90%.
^ The MAP is greater than or equal to 20 kPa but less than or equal to 80 kPa.
^ The throttle position is greater than or equal to 5% but less than or equal to 60%.
^ The engine speed is greater than or equal to 800 RPM but less than or equal to 3000 RPM.

ACTION TAKEN WHEN THE DTC SETS
The VCM turns on the Malfunction Indicator Lamp (MIL) after 2 consecutive driving cycles with the fault active.

CONDITIONS FOR CLEARING THE MIL/DTC
The VCM turns the MIL off after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 40°F from the start-up coolant temperature and the engine coolant temperature exceeds 160°F during that same ignition cycle) or the scan tool clearing feature has been used.

DIAGNOSTIC AIDS
Make a visual check of the vacuum hoses. Check the throttle body for a possible cracked, broken, or plugged vacuum block. Check the engine for possible mechanical problems.

Refer to Carbon Particle Removal from Evaporative Emissions (EVAP) System before starting repairs.

TEST DESCRIPTION
The numbers below refer to the step numbers in the diagnostic table.

2. The solenoid valve will click when commanded ON and OFF by the scan tool. This step determines if the VCM can control the solenoid valve.
3. Ported (off idle) vacuum is used at the solenoid valve. The Vacuum will only be seen off idle with a vacuum gauge.
5. If voltage is not available to the solenoid valve, the VCM will not be able to command it ON or OFF.
4. Disconnecting the vacuum switch opens the 5 volt reference circuit from the VCM which indicates that purge is present. Leaving the switch disconnected will cause a DTC P1441.
6. Determines if the solenoid valve couldn't be commanded due to an electrical circuit problem or faulty solenoid.