Circuit Description
A battery voltage is supplied to the evaporative emission (EVAP) canister vent solenoid valve. The control module grounds the EVAP canister vent solenoid valve control circuit to close the valve by means of an internal switch called a driver. The scan tool displays the commanded state of the EVAP canister vent solenoid valve as ON or OFF. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, this DTC sets.
The following table illustrates the relationship between the ON and OFF states, and the venting or not venting states of the EVAP canister vent solenoid valve.
Control Module Command | EVAP Canister Vent Solenoid Valve Position |
|---|---|
ON | Not Venting |
OFF | Venting |
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0449 Evaporative Emission (EVAP) Vent Solenoid Control Circuit
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The system voltage is between 11-18 volts. |
Conditions for Setting the DTC
| • | The control module detects that the commanded state of the driver and the actual state of the control circuit do NOT match. |
| • | The above condition is present for a minimum of 5 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Do you hear or feel a click from the EVAP canister vent solenoid valve when commanded ON and OFF? | Go to Step 3 | Go to Step 4 |
3 |
Did the DTC fail this ignition? | Go to Step 4 | Go to Testing for Intermittent Conditions and Poor Connections |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 11 |
5 |
Does the test lamp turn ON or OFF with each command? | Go to Step 9 | Go to Step 6 |
6 | Does the test lamp remain illuminated with each command? | Go to Step 8 | Go to Step 7 |
7 | Test the control circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 14 | Go to Step 10 |
8 | Test the control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 14 | Go to Step 10 |
9 | Test for an intermittent and for a poor connection at the EVAP canister vent solenoid valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 14 | Go to Step 12 |
10 | Test for an intermittent and for a poor connection at the control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
11 |
Did you complete the repair? | Go to Step 14 | -- |
12 | Replace the EVAP canister vent solenoid valve. Did you complete the replacement? | Go to Step 14 | -- |
13 | Replace the powertrain control module (PCM). Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 14 | -- |
14 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 15 |
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
