P1441
Diagnostic Chart:
Electrical:
CIRCUIT DESCRIPTION
The evaporative system includes the following components:
^ The fuel tank
^ The EVAP vent solenoid
^ The fuel tank pressure sensor
^ The fuel pipes and hoses
^ The vapor lines
^ The fuel cap
^ The evaporative emission canister
^ The purge lines
^ The EVAP purge solenoid
The EVAP purge solenoid valve allows the manifold vacuum to purge the canister. The Vehicle Control Module (VCM) supplies a ground in order 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 duty cycle (pulse width) is determined by the engine operating conditions including the load, the throttle position, the coolant temperature, and the ambient temperature. The duty cycle is calculated by the VCM, and the purge solenoid is commanded ON when certain conditions have been met.
The system checks for conditions that cause the EVAP system to purge continuously by commanding the EVAP vent solenoid ON and the EVAP purge solenoid OFF (EVAP vent solenoid CLOSED, EVAP purge PWM 0%). If the fuel tank pressure level increases during the test, a continuous purge flow condition is indicated. The following items can cause this condition:
^ A leaking EVAP purge solenoid
^ A grounded EVAP purge solenoid driver circuit
CONDITIONS FOR SETTING THE DTC
The following conditions will set the DTC:
^ No MAP sensor DTCs
^ No TP sensor DTCs
^ No VSS DTCs
^ No HO2S DTCs
^ No ECT DTCs
^ No IAT sensor DTCs
^ DTC P0125 not set
^ Fuel Level is greater than 12.5% but less than 87.5%
^ System voltage is greater than 10 volts but less than 17 volts
Cold Start Test
^ ECT is greater than 3.75°C but less than 30°C
^ IAT is greater than 3.75°C but less than 30°C
^ If IAT is greater than ECT the difference between ECT and IAT is less than 1.5°C
^ OR if ECT is greater than IAT the difference between ECT and IAT is less than 8.25°C
^ The Baro is greater than 72.5 kPa
Excess Vacuum Test
^ Vent Solenoid commanded OPEN
^ Fuel tank vacuum is less than 7 in. H2O
Weak Vacuum Test
^ TP is less than 75%
^ Vehicle speed is less than 65 MPH
^ Fuel tank vacuum is greater than one of the following:
- 9 in. H2O within 30 seconds
- 11 in. H2O within 50 seconds
- 13 in. H2O within 80 seconds
Purge Valve Leak Test
^ Purge valve closed
^ TP is greater than 0% but less than 99.6%
^ MAP is greater than 10 kPa
^ Fuel tank vacuum is greater than or equal to 12 in. H2O for 2 seconds within less than or equal to 37.5 seconds after a 30 second delay
ACTION TAKEN WHEN THE DTC SETS
The VCM will turn ON the 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 drive trips when the test has Run and Passed and not Failed.
^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle).
^ Use the scan tool Clear Information function.
^ Disconnect the VCM battery feed for 30 seconds.
DIAGNOSTIC AIDS
A poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation may cause an intermittent.
Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked 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 Symptoms. Testing and Inspection
TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table:
2. Determines if the EVAP Purge Solenoid is leaking.
3. Determines if the EVAP canister Purge Valve Driver circuit is shorted to ground.
4. Determines if the EVAP canister Purge Valve Driver circuit wiring or VCM is at fault.