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 |
If any of these conditions are present, a DTC P1441 sets. This DTC is a type B DTC.
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 |
| • | The Baro is greater than 75 kPa. |
| • | No EGR DTCs |
| • | ECT is less than or equal to 115°C |
| • | Power Up IAT is greater than 3°C |
| • | IAT is less than or equal to 80°C |
| • | ECT/IAT start up is less than or equal to 10°C |
| • | Purge DC is less than or equal to 5% |
| • | Manifold vacuum is greater than or equal to 25 kPa but less than 100 kPa |
| • | Throttle position is greater than or equal to 4% but less than or equal to 50% |
| • | Engine speed is greater than or equal to 550 rpm but less than or equal to 3000 rpm |
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 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
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 Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
When commanded by the scan tool, the EVAP. Canister purge solenoid valve should make a clicking noise. This verifies if the VCM has control of solenoid valve.
-
The canister purge vacuum switch is normally closed when no vacuum (purge) is present. With the key ON and the engine off, there shouldn't be any vacuum (purge) present in the EVAP System.
-
Determines if the reason the EVAP. Canister purge solenoid valve could not be commanded was the result of a faulty solenoid, faulty wiring or faulty VCM.
-
Determines if the canister purge vacuum switch, wiring or VCM is at fault.
-
The VCM supplies a 5 volt reference to the canister purge vacuum switch on the EVAP solenoid control circuit. This step determines if the wiring or VCM is at fault.
-
If the 5 volt reference was not available to the canister purge vacuum switch and no other DTCs were set, then the connection is faulty or the circuit is open between the sensor and the wiring splice from the 5 volt reference circuit.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
|
Important: Before clearing DTCs, use the scan tool in order to record the freeze frame and the failure records for reference because the Clear Info function will lose the data. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
|
Important: If DTC P0107 is set, diagnose that DTC first.
Does the valve turn on and off when commended? | -- | |||
Does the test lamp flash ON and OFF? | -- | |||
Replace the EVAP canister purge solenoid. Refer EVAP Canister Purge Solenoid . Is the action complete? | -- | -- | ||
Monitor the scan tool display. Does the display read EVAP Duty Cycle at the specified value? | 0% | Go to Diagnostic Aids | ||
Does display read PURGE? | -- | |||
7 | Connect a jumper between terminals A and B and Monitor the scan tool display. Does the scan tool read NO PURGE? | -- | ||
8 | Check connections at the canister purge vacuum switch. Was a problem found? | -- | ||
9 | Repair connections at canister purge vacuum switch. Refer to Wiring Repairs in Engine Electrical. Is the action complete? | -- | -- | |
10 | Replace the canister purge vacuum switch. Refer to Evaporative Emission Vacuum Switch . Is the action complete? | -- | -- | |
11 |
Is the voltage about the specified value? | 12.0V | ||
12 | Check for open ground circuit and/or faulty connection. Was a problem found? | -- | ||
13 | Repair the open ground circuit and the faulty connection if necessary. Refer to Wiring Repairs in Engine Electrical. Is the action complete? | -- | -- | |
14 |
Is the action complete? | -- | -- | |
15 | Replace the VCM. Important: If the VCM is faulty, reprogram the VCM. Refer to VCM Replacement/Programming . Is the action complete? | -- | -- | |
16 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
17 | Using the scan tool, select the Capture Info and the Review Info. Are any DTCs displayed that have not been diagnosed? | -- | Go to The Applicable DTC Table | System OK |
