Refer to Engine Controls Schematic
Power, Ground, MAF, EVAP, and EGR
.
Circuit Description
Output driver modules (ODMs) are used by the powertrain control module (PCM) to turn on many of the current-driven devices that are needed to control various engine and transmission functions. Each ODM is capable of controlling up to 7 separate outputs by applying ground to the device which the PCM is commanding ON. ODMs have the capability of diagnosing each output circuit individually. DTC P0449 set indicates an improper voltage level has been detected on the output circuit which controls the evaporative emissions (EVAP) canister vent solenoid valve.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The ignition voltage is between 9.0-18.0 volts. |
Conditions for Setting the DTC
| • | An improper voltage level has been detected on the output circuit which controls the EVAP canister vent solenoid valve. |
| • | The above condition is present for at least 30 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Check for the following conditions:
| • | A faulty connection at the PCM--Inspect the harness connectors for: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Faulty terminal-to-wire connection |
| • | A damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the PCM, turn ON the ignition and observe a voltmeter connected between the solenoid control circuit and ground at the PCM harness connector while moving the connectors and the wiring harnesses that are related to the solenoid. A change in the voltage will indicate the location of the malfunction. |
Many situations may lead to an intermittent condition. Perform each inspection or test as directed.
Important: : Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
| • | Loose terminal connection |
| - | Use a corresponding mating terminal to test for proper tension. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| - | Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Refer to Testing for Intermittent Conditions and Poor Connections , and to Connector Repairs in Wiring Systems for diagnosis and repair. |
| • | Damaged harness--Inspect the wiring harness for damage. If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
| • | Inspect the powertrain control module (PCM) and the engine grounds for clean and secure connections. Refer to Wiring Repairs in Wiring Systems for diagnosis and repair. |
If the condition is determined to be intermittent, reviewing the Snapshot or Freeze Frame/Failure Records may be useful in determining when the DTC or condition was identified.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The Powertrain On Board Diagnostic (OBD) System Check prompts you to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool.
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Listen for a click when the vent solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.
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This step tests for voltage at the feed side of the solenoid.
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This step verifies that the PCM is providing ground to the solenoid.
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This step tests if ground is constantly being applied to the solenoid.
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The PCM utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Did you perform the Powertrain On Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | ||
Does the valve turn ON and OFF with each command? | -- | Go to Diagnostic Aids | Go to Step 3 | |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 10 | |
Does the test lamp turn ON and OFF with each command? | -- | Go to Step 8 | Go to Step 5 | |
Does the test lamp remain illuminated with each command? | -- | Go to Step 7 | Go to Step 6 | |
6 | Test the control circuit of the solenoid for a short to voltage or an open. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
7 | Test the control circuit of the solenoid for a short to ground. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | Inspect for faulty connections at the valve. Refer to Connector Repairs and Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
9 | Inspect for faulty connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
10 | Repair the feed circuit of the valve. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 13 | -- |
11 | Replace the valve. Refer to Evaporative Emission Vent Valve Replacement . Is the action complete? | -- | Go to Step 13 | -- |
|
Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | Go to Step 13 | -- | |
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
