P0449

Schematic:

CIRCUIT DESCRIPTION
A voltage is supplied directly to the EVAP Canister Vent valve. The PCM controls the solenoid 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. Each driver has a fault line which the PCM monitors. The voltage of the control circuit should be low (near 0 volts) when the PCM commands a component ON. The voltage potential of the circuit should be high (near the battery voltage) when the PCM commands the control circuit to a component OFF. If the fault detection circuit senses a voltage other than what the PCM is expects, the fault line status changes causing the DTC to set.

CONDITIONS FOR RUNNING THE DTC
^ The engine speed is more than 400 RPM.
^ The ignition voltage is between 6.0 volts and 18.0 volts.

CONDITIONS FOR SETTING THE DTC
^ The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.
^ The conditions are present for a minimum of 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM turns the Malfunction Indicator Lamp (MIL) OFF after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A last test failed (current DTC) clears when the diagnostic runs and does not fail.
^ A History DTC clears after 40 consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ Use a scan tool in order to clear the MIL/DTC.

DIAGNOSTIC AIDS

IMPORTANT:
^ Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.
^ For any test that requires probing the PCM or a component harness connector, use the J 35616-A connector test adapter kit. Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Diagrams.

Test the solenoid ignition feed circuit and control circuit for excessive resistance if an audible click cannot be heard when the solenoid is commanded ON and OFF.

Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set.

The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.

For an intermittent, refer to Symptoms. Symptom Related Diagnostic Procedures

TEST DESCRIPTION

Steps 1 - 4:

Steps 5 - 15:

The numbers below refer to the step numbers on the diagnostic table.
2. Listen for an audible click when the solenoid operates. Be sure that both the ON and the OFF states are commanded. Repeat the commands as necessary.
4. This step tests for voltage at the coil side of the EVAP vent solenoid. The ENG CONTROL fuse supplies power to the EVAP vent solenoid.
5. This step verifies that the PCM is providing ground to the EVAP vent solenoid.
6. This step tests if a ground is constantly being applied to the EVAP vent solenoid.