Circuit Description
The evaporative emission (EVAP) canister purge valve is used to purge fuel vapor from the EVAP canister to the intake manifold. The EVAP canister purge valve is pulse width modulated (PWM). Ignition voltage is supplied directly to the EVAP canister purge 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. If the ECM detects the control circuit voltage is less than a predetermined value when the circuit is commanded OFF, this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC.
DTC P0444 Evaporative Emission (EVAP) Purge Solenoid Control Circuit Low Voltage
Conditions for Running the DTC
| • | The ignition is ON, or the engine is running. |
| • | DTC P0444 runs continuously once the above condition is met. |
Conditions for Setting the DTC
| • | The ECM detects an open condition on the EVAP canister purge valve control circuit when the driver is commanded OFF. |
| • | The condition exists for less than 1 second. |
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate after 3 consecutive trips with a fail. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Diagnostic Aids
| • | Use the Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector. |
| • | If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Indeterminate to Fault if there is a condition with the circuit or a connection. The output driver module (ODM) information is in the ODM data list. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step determines if a condition exists. The EVAP canister purge valve is PWM. An audible click should be heard when the EVAP canister purge valve is commanded ON. Repeat the command as necessary.
-
This step tests the feedback voltage from the ECM. If a voltage is not available, this indicates an internal ECM condition.
-
This step tests the ignition 1 voltage circuit to the EVAP canister purge valve.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connect End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |
Do you hear an audible click from the EVAP canister purge valve? | -- | Go to Step 4 | Go to Step 3 | |
3 |
Did the DTC fail this ignition? | -- | Go to Step 4 | Go to Diagnostic Aids |
4 |
Does the test lamp illuminate or flash? | -- | Go to Step 5 | Go to Step 6 |
Measure the voltage from the control circuit of the EVAP canister purge valve to a good ground with a DMM. Is the voltage within the specified range? | 3.6 - 4.2 V | Go to Step 8 | Go to Step 9 | |
Connect a test lamp between the ignition 1 voltage circuit of the EVAP canister purge valve to a good ground. Does the test lamp illuminate? | -- | Go to Step 7 | Go to Step 10 | |
7 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | Test for an intermittent and for a poor connection at the EVAP canister purge valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
9 | Test for an intermittent and for a poor connection at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 12 |
10 |
Important: The ignition 1 voltage circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition 1 voltage circuit. Did you complete the repair? | -- | Go to Step 13 | -- |
11 | Replace the EVAP canister purge valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
12 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 |
14 | Are there any DTCs that have not been diagnosed? | -- | System OK | |
