Refer to
EVAP and EGR Controls
for wiring view.
Circuit Description
Canister purge is controlled by a solenoid valve that allows manifold vacuum to purge the canister. The Powertrain Control Module (PCM) supplies a ground to energize the solenoid valve (purge ON). The EVAP purge solenoid control is Pulse Width Modulated (PWM) or turned ON and OFF several times a second. The duty cycle (pulse width) is determined by engine operating conditions including load, throttle position, coolant temperature and ambient temperature. The duty cycle is calculated by the PCM and the output is commanded when the appropriate conditions have been met.
The EVAP purge vacuum switch is a normally closed switch positioned in the purge line between the canister and the EVAP purge solenoid. The EVAP purge vacuum switch will open when vacuum increases to greater than 5 inches of water in the purge line. The PCM monitors the EVAP purge vacuum switch signal to determine if the evaporative emission control system is working properly. If the switch is open (purge flow detected) when the PCM is not commanding the EVAP purge solenoid ON, DTC P1441 will be set.
Conditions for Setting the DTC
| • | DTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0401, P0506, P0507, P1406, and P1133 not set. |
| • | The BARO is greater than 83 kpa. |
| • | The ECT is between 4°C (39°F) and 30°C (86°F) at engine start up. |
| • | Intake air temperature is between 2°C (36°F) and 30°C (86°F) at engine start up. |
| • | The ECT and IAT are within 6°C (43°F) of one another at engine start up. |
| • | The engine run time is less than 22 minutes. |
| • | The TP sensor is between 9 % and 20 %. |
| • | The engine RPM is between 1700 and 4000 RPM. |
| • | The MAP sensor is between 20 kpa and 70 kpa. |
| • | EVAP Vacuum switch indicates OFF when the EVAP Purge Valve is commanded to 100%. |
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) will illuminate. |
| • | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
| • | A history DTC is stored. |
| • | Coolant fan turns ON. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | The MIL/DTCs can be cleared by using the scan tool. |
Diagnostic Aids
Although this DTC is considered a type A diagnostic refer toPowertrain Control Module (Control Modules) and Powertrain Control Module (Serial Data Communication) , because it acts like a type B diagnostic under certain conditions. Whenever this diagnostic reports the system has passed, or if the battery is disconnected, the diagnostic must fail twice before setting a DTC. The initial failure is not reported to the diagnostic executive or displayed on a scan tool. A passing system always reports to the diagnostic executive immediately.
Check for the following conditions:
| • | Poor connection at PCM. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Incorrect vacuum line routing. Verify that the source vacuum line routing to the EVAP canister purge valve is correct and that the EVAP purge and source vacuum lines to the EVAP canister purge valve are not switched. |
| • | Refer to Carbon Particle Removal from EVAP System for further procedures. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
-
The OBD System Check prompts the technician to use the Capture Info . selection on the scan tool. This creates an electronic copy of the freeze frame data taken when the fault occurred. The information is then stored in the scan tool for later reference.
-
If an EVAP canister purge valve electrical fault is present, the purge system will not operate correctly. Repairing the electrical fault will very likely correct the condition that set DTC P1441.
-
Checks for a stuck open EVAP canister purge valve.
-
If the EVAP purge and engine vacuum lines are switched at the EVAP canister purge valve, the solenoid valve will leak vacuum.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
Does scan tool show vacuum switch purging? | -- | |||
3 | With hose still removed, start engine and close the purge solenoid with the scan tool. Is vacuum present at the canister side of the vacuum switch? | -- | ||
Check the purge hose for kinks or restriction between the vacuum switch and the canister. Was problem found? | -- | |||
5 |
Is vacuum greater then specified value? | 5" Hg | If No problem found Go to Diagnostic Aids | |
6 |
| -- | ||
Replace the canister purge vacuum switch, refer to Diagnostic Aids . Is the action complete? | -- | -- | ||
8 | Using the scan tool check the EVAP Canister purge solenoid circuit for an open or short. Repair as necessary. Was a repair necessary? | -- | ||
9 | Replace the EVAP purge solenoid, refer to Diagnostic Aids . Is the action complete? | -- | -- | |
10 | Replace the vacuum hose. Is the action complete? | -- | -- | |
11 | Replace the EVAP canister, refer to Diagnostic Aids . Is the action complete? | -- | -- | |
12 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
13 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK, |
