The evaporative emission (EVAP) vent solenoid valve is used for EVAP system diagnostics. The EVAP vent solenoid valve is a normally open valve. Battery voltage is supplied directly to the EVAP vent solenoid valve. The engine control module (ECM) controls the solenoid by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 5 seconds.

DTC P0449 is a Type B DTC.

DTC P0449 is a Type B DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Evaporative Emission Control System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, command the EVAP Vent Solenoid ON and OFF with a scan tool. You should hear the solenoid click when commanded ON and OFF.
2. Engine idling, command the EVAP vent solenoid ON and OFF with a scan tool while observing the following control circuit status parameters:

•	EVAP Vent Sol Short Gnd Test Status

•	EVAP Vent Sol Open Test Status

•	EVAP Vent Sol Short Volts Test Status

Each parameter should display OK or Not Run.

3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

1. Ignition OFF, disconnect the harness connector at the EVAP vent solenoid.
2. Ignition ON, verify a test lamp illuminates between the B+ voltage circuit terminal B and ground.

⇒	If the test lamp does not illuminate, test the B+ voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ voltage circuit fuse is open, test all components connected to the B+ voltage circuit and replace as necessary.

3. Test for 2.5-3.5 V between the control circuit terminal A and ground.

⇒	If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.

⇒	If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Command the EVAP vent solenoid ON and OFF with a scan tool. The DMM should transition from 2.5-3.5 V when OFF to less than 0.1 V when commanded ON.

⇒	If the circuit voltage does not correspond to the specified values, replace the ECM.

5. If all circuits test normal, test or replace the EVAP vent solenoid.

1. Ignition OFF, disconnect the harness connector of the EVAP vent solenoid.
2. Test for 15-25 Ω between the control terminal A and the B+ voltage terminal B.

⇒	If not within the specified range, replace the EVAP vent solenoid.

3. Test for infinite resistance between each terminal and the EVAP vent solenoid housing.

⇒	If not the specified value, replace the EVAP vent solenoid.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.