For 1990-2009 cars

### 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 | P0445 | 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 runs continuously once the above conditions are met.

### Conditions for Setting the DTC

#### P0444

The ECM detects the EVAP purge solenoid control circuit is open.

#### P0445

The ECM detects the EVAP purge solenoid control circuit is shorted to ground or voltage.

### 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

Engine Controls Schematics

#### Connector End View Reference

• | Engine Control Module Connector End Views

• | Engine Controls Connector End Views

#### Description and Operation

Evaporative Emission Control System Description

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### Circuit/System Verification

1. With a scan tool, command the EVAP Purge Solenoid ON. You should hear an audible click for about 3-5 seconds.
2. 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

1. Ignition OFF, disconnect the harness connector of the EVAP purge solenoid.
2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit and battery ground.

⇒ | If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary.

3. Connect a test lamp between the control circuit and the ignition 1 voltage circuit.
4. Command the EVAP purge solenoid ON with a scan tool. The test lamp should turn ON and OFF for 3-5 seconds.

⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If circuit/connections test normal, replace the ECM.

⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If circuit/connections test normal, replace the ECM.

5. If all circuits/connections test normal, test or replace the EVAP purge solenoid.

### Component Testing

1. Measure for 24-28 ohms of resistance between the terminals of the EVAP purge solenoid.

⇒ | If the resistance is not within the specified range, replace the EVAP purge solenoid.

2. Test for infinite resistance between each terminal of the EVAP purge solenoid and the EVAP purge solenoid housing.

⇒ | If less than infinite resistance, replace the EVAP purge solenoid.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Evaporative Emission Canister Purge Solenoid Valve Replacement

• | Control Module References for engine control module replacement, setup, and programming