P0449

CIRCUIT DESCRIPTION
An ignition voltage is supplied directly to the evaporative emission (EVAP) canister vent valve. The control module controls the EVAP vent valve by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. The control module monitors the status of the driver. If the control module detects an incorrect voltage for the commanded state of the driver, DTC P0449 sets.

CONDITIONS FOR RUNNING THE DTC
^ The engine speed is more than 400 RPM.
^ The system voltage is between 6-18 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 conditions are 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.

TEST DESCRIPTION

Steps 1-3:

Steps 4-15:

The numbers below refer to the step numbers on the diagnostic table.
2. Listen for a click when the valve operates. Verify that both the ON and the OFF states are commanded. Repeat the commands as necessary.
5. This step verifies that the control module is providing ground to the EVAP vent valve.
6. This step tests if the EVAP vent valve control circuit is grounded.