P1441

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 teed 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
Test Conditions

^ The Evaporative Emissions (EVAP) vacuum switch state = high vacuum for a period greater than 4 seconds.
^ The EVAP purge solenoid diagnostic vacuum switch DTC is not set.
^ No IAC DTCs set.
^ No MAP DTCs set.
^ No TP sensor DTCs set.
^ No EGR DTCs set.
^ The BARO is greater than 75 kPa.
^ The ECT is less than 110°C.
^ The IAT is less than 90°C.
^ The difference between the ECT and the IAT reading is less than 90°C.
^ The purge DC is less than 0%.
^ The MAP is at least than 20 kPa.
^ The throttle position is greater than 5% but less than 60%.
^ The engine speed is greater than 800 RPM but is less than 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
A poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation may cause an intermittent.

Thoroughly check any circuitry, that is suspected as causing the intermittent complaint, for the following conditions:

^ Backed out terminals.
^ Improper mating.
^ Broken locks.
^ Improperly formed or damaged terminals.
^ Poor terminal to wiring connections.
OR
^ Physical damage to the wiring harness.

Refer to Intermittents.

Refer to Carbon Particle Removal from EVAP System before starting repairs.

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

3. This step checks for the possibility of vacuum being trapped in the EVAP system.
4. This step begins the checks for a bad Vacuum switch.
8. This step begins the checks for a bad EVAP Purge solenoid.