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 Powerup 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 the MIL ON after 2 consecutive driving cycles with the fault active.
Conditions for Clearing the MIL/DTC
The VCM turns OFF the MIL 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 (the coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature exceeds 71°C (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 EVAP System before starting repairs.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
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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.
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Ported (off idle) vacuum is used at the solenoid valve. The Vacuum will only be seen off idle with a vacuum guage.
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If voltage is not available to the solenoid valve, the VCM will not be able to command it ON or OFF.
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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.
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Determines if the solenoid valve couldn't be commanded due to an electrical circuit problem or faulty solenoid.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Use the scan tool in order to record the Freeze Frame and the Failure Records. Using the Clear Info function will lose this data. Was the On-Board Diagnostic (OBD) System Check performed? | -- | ||
Does the EVAP Canister Purge Solenoid Valve turn ON and OFF when commanded? | -- | |||
Allow the throttle to return to idle. Is the specified amount of the vacuum present? | 2500 RPM 10 in. Hg (34 kPa)1 | |||
Does the scan tool display the EVAP Vacuum Switch ON? | -- | |||
Is the test lamp ON? | -- | |||
Does the test lamp flash ON and OFF? | -- | |||
7 | Refer to Diagnostic Aids. | -- | -- | -- |
8 | Inspect the hoses to the vacuum switch for being pinched, kinked or clogged. Was a problem found? | -- | ||
9 | Repair the opening in the ignition feed circuit. Refer to Wiring Repairs in Engine Electrical. Is the action complete? | -- | -- | |
10 | Replace the faulty EVAP canister purge solenoid. Refer to Diagnostic Aids. Refer to EVAP Canister Purge Solenoid . Is the action complete? | -- | -- | |
11 | Check the EVAP purge solenoid control circuit for an open or short to voltage. Refer to Wiring Repairs in Engine Electrical. Was a problem found? | -- | ||
12 | Check if the EVAP vacuum switch signal circuit is shorted to ground. Was a problem found? | -- | ||
13 | Replace the EVAP vacuum switch. Refer to Diagnostic Aids. Refer to EVAP Vacuum Switch . Is the action complete? | -- | -- | |
14 | Repair as necessary. Is the action complete? | -- | -- | |
15 | Replace the VCM. Important: If the VCM is faulty, program the new VCM. Refer to VCM Replacement/Programming . Is the action complete? | -- | -- | |
16 |
Does the scan tool indicate that this diagnostic Ran and Passed? | -- | ||
17 | Use the scan tool to select Capture Info and Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC Table | System OK |
