DTC P0449 Evaporative Emission (EVAP) Vent Solenoid Control
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PostPosted: Fri Nov 12, 2004 8:00 am    Post subject: DTC P0449 Evaporative Emission (EVAP) Vent Solenoid Control Reply with quote

DTC P0449 Evaporative Emission (EVAP) Vent Solenoid Control Circuit


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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 OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
  • A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
  • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
  • Use a scan tool in order to clear the MIL and the 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 connector test adapter kit . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

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 .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 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.

  2. This step tests for voltage at the coil side of the EVAP vent solenoid. The ENG CNTRL fuse supplies power to the EVAP vent solenoid.

  3. This step verifies that the PCM is providing ground to the EVAP vent solenoid.

  4. This step tests if a ground is constantly being applied to the EVAP vent solenoid.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check ?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Idle the engine at the normal operating temperature.
  2. With the scan tool, command the solenoid ON and OFF.

Does the solenoid turn ON and OFF when commanded?

--

Go to Step 3

Go to Step 4

3

  1. Review the Freeze Frame and/or Failure records data for this DTC.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for running the DTC as specified in the supporting text or as close to the Freeze Frame and/or Failure records data that you observe.

Does this DTC reset?

--

Go to Diagnostic Aids

Go to Intermittent Conditions

4

  1. Turn OFF the ignition.
  2. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  3. Lower the fuel tank. Refer to Fuel Tank Replacement .
  4. Disconnect the solenoid electrical connector.
  5. Turn ON the ignition, with the engine OFF.
  6. Probe the coil side feed circuit of the EVAP vent solenoid with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

--

Go to Step 5

Go to Step 11

5

  1. Connect a test lamp between the control circuit of the EVAP vent solenoid and the coil side feed circuit of the EVAP vent solenoid. Refer to Probing Electrical Connectors in Wiring Systems .
  2. With a scan tool, command the EVAP vent solenoid ON and OFF.

Does the test lamp turn ON and 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

  1. Test the control circuit of the EVAP vent solenoid for a short to voltage or an open. Refer to Circuit Testing in Wiring Systems.
  2. If you find a condition, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

8

  1. Test the control circuit of the EVAP vent solenoid for a short to ground. Refer to Circuit Testing in Wiring Systems.
  2. If you find a condition, repair as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

9

  1. Inspect for poor connections at the EVAP vent solenoid. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
  2. If you find a condition, repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

10

  1. Inspect for poor connections at the PCM. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
  2. If you find a condition, repair as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

11

Repair the coil side feed circuit of the EVAP vent solenoid. Refer to Wiring Repairs in Wiring Systems .

Is the action complete?

--

Go to Step 14

--

12

Replace the EVAP vent solenoid. Refer to Evaporative Emission (EVAP) Vent Valve Replacement .

Is the action complete?

--

Go to Step 14

--

13

Important:

Program the replacement PCM. Refer to PCM Replacement/Programming .

Replace the PCM.

Is the action complete?

--

Go to Step 14

--

14

  1. Use a scan tool in order to clear the DTCs.
  2. Operate vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

Go to Step 15

15

With a scan tool, review the Stored information (capture info).

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List/Type

System OK

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