P0449

DTC P0449

DTC DESCRIPTOR

DTC P0449
Evaporative Emission (EVAP) Vent Solenoid Control Circuit

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection






CIRCUIT/SYSTEM DESCRIPTION
Battery voltage is supplied to the 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.

CONDITIONS FOR RUNNING THE DTC
- The ignition is ON.
- The system voltage is between 9-18 volts.
- DTC P0449 runs continuously when the above conditions are met.

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 for a minimum of 12 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.

CIRCUIT/SYSTEM VERIFICATION
1. With the ignition ON and the engine OFF, command the EVAP vent solenoid ON and OFF with a scan tool.
2. Listen for a click when the valve operates. Verify that both the ON and the OFF states are commanded.

CIRCUIT/SYSTEM TESTING
1. Turn OFF the ignition.
2. Disconnect the EVAP canister vent solenoid valve.
3. Turn ON the ignition, with the engine OFF.
4. Probe the battery positive voltage circuit of the EVAP canister vent solenoid valve with a test lamp that is connected to a good ground.
- If the test lamp does not illuminate, test the circuit for an open or for a short to ground.
5. Connect a test lamp between the control circuit of the EVAP vent solenoid valve and the battery positive voltage circuit of the EVAP canister vent solenoid valve at the EVAP vent valve harness connector.
- If the test lamp illuminates, test the control circuit of the EVAP canister vent solenoid valve for a short to ground.
6. Command the EVAP canister vent solenoid ON and OFF.
- If the test lamp does not illuminate with the commanded state of the valve, test the control circuit of the EVAP canister vent solenoid valve for a short to voltage or an open.
- If the circuits and the control module test normal, replace the EVAP canister vent solenoid valve.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Evaporative Emission (EVAP) Canister Vent Solenoid Valve Replacement
- Control Module References for engine control module (ECM) replacement, setup, and programming Verification Tests