Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
DTC Descriptors
DTC P0444: Evaporative Emission (EVAP) Purge Solenoid Control Circuit Open.DTC P0445: Evaporative Emission (EVAP) Purge Solenoid Control Circuit Shorted.
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ignition 1 Voltage | P0444 | P0444 | -- | -- |
EVAP Canister Purge Valve Control Circuit | P0445 | P0444 | P0445 | -- |
Circuit/System 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.
Conditions for Running the DTC
| • | The ignition is ON or the engine is operating. |
| • | The DTCs run continuously once the above conditions are met. |
Conditions for Setting the DTC
P0444
The ECM detects the EVAP purge solenoid control circuit is open for greater than 1 second, during a purge event.
P0445
The ECM detects a short to ground or a short to voltage on the EVAP canister purge valve control circuit for greater than 5 seconds.
Action Taken When the DTC Sets
DTC P0444, and P0445 are Type B DTCs.
Conditions for Clearing the DTC
DTC P0444, and P0445 are Type B DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation:
Evaporative Emission Control System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
- Ignition ON, command the EVAP purge solenoid ON with a scan tool . You should hear and feel an audible click for about 3-5 seconds.
- If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the EVAP purge solenoid.
- Ignition ON, test for B+ between the ignition 1 voltage circuit and ground.
- Connect a test lamp between the control circuit and the ignition 1 voltage circuit.
- Command the EVAP purge solenoid ON with a scan tool. The test lamp should turn ON and OFF for about 3-5 seconds.
- If all circuits test normal, test or replace the EVAP purge solenoid.
| ⇒ | If less than B+, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. |
| ⇒ | If the test lamp is always ON, test for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | If the test lamp is always OFF, test for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
Component Testing
- Test for 24-28 ohms of resistance between the terminals of the EVAP purge solenoid.
- Test for infinite resistance between each terminal of the EVAP purge solenoid and the EVAP purge solenoid housing.
| ⇒ | If not within the specified range, replace the EVAP purge solenoid. |
| ⇒ | If less than infinite resistance, replace the EVAP purge solenoid. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for engine control module replacement, setup, and programming
