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 provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0403: Exhaust Gas Recirculation (EGR) Solenoid Control Circuit
DTC P0489: Exhaust Gas Recirculation (EGR) Solenoid Control Circuit Low Voltage
DTC P0490: Exhaust Gas Recirculation (EGR) Solenoid Control Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition 1 Voltage | P0340, P0342, P0458, P0489 | P0403 | -- | --
Solenoid Control | P0406, P0489 | P0403 | P0490 | P0404
5-Volt Reference | P0106, P0405, P2122, P2138 | P0405 | -- | --
EGR Position Sensor Signal | P0405 | P0405, P046C | P0406 | P0404
Low Reference | -- | P0406, P046C | -- | --

### Typical Scan Tool Data

#### EGR Position Sensor

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Engine operating in Closed Loop Parameter Normal Range: 0-4%
Ignition 1 Voltage | -- | -- | --
Solenoid Control | 99% | -- | --
5-Volt Reference | 0% | 0% | 99%*
EGR Position Sensor Signal | 0% | 0% | 99%*
Low Reference | -- | 0% | --
* Internal ECM damage may occur if the circuit is shorted to B+.

### Circuit Description

Voltage is provided to the exhaust gas recirculation (EGR) valve by the ignition 1 voltage circuit through a fuse. Ground is provided to the EGR valve on the control circuit by a low side driver within the engine control module (ECM). The ECM monitors the voltage on the control circuit of the EGR valve to determine if a failure is present.

The ECM monitors the position of the EGR valve through the EGR valve position sensor. The EGR valve position sensor sends a feedback voltage on the signal circuit to the ECM. The EGR position sensor voltage varies depending on the position of the EGR valve.

The EGR valve utilizes the following circuits:

• | An ignition 1 voltage circuit

• | A control circuit

• | A 5-volt reference circuit

• | A signal circuit

• | A low reference circuit

### Conditions for Running the DTC

• | The engine is running.

• | The DTCs run continuously when the above condition is met.

### Conditions for Setting the DTC

#### P0403

The ECM detects an open on the EGR solenoid control circuit.

#### P0489

The ECM detects a short to ground on the EGR solenoid control circuit.

#### P0490

The ECM detects a short to voltage on the EGR solenoid control circuit

### Action Taken When the DTC Sets

DTC P0403, P0489, and P0490 are Type B DTCs.

### Conditions for Clearing the MIL/DTC

DTC P0403, P0489, and P0490 are Type B DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Exhaust Gas Recirculation (EGR) 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

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, observe the scan tool Actual EGR position parameter while commanding the EGR valve ON and OFF. The reading should change from 0 percent to 99 percent with each command.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Ignition OFF, and the MAIN fuse removed, disconnect the harness connector at the EGR valve.
2. Ignition ON, verify a test lamp illuminates between the ignition 1 voltage circuit terminal E and 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. Ignition OFF, verify a test lamp does not illuminate between the control circuit terminal A and 12 volts.

⇒ | If test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Install the MAIN fuse. Ignition ON, command the EGR valve to 99 percent with a scan tool, The test lamp should illuminate.

⇒ | If test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the EGR valve.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the EGR valve.
2. Test for 6-10 ohms of resistance between the ignition 1 voltage terminal E and the control terminal A.

⇒ | If not within the specified range, replace the EGR valve.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Exhaust Gas Recirculation Valve Replacement

• | Control Module References for ECM replacement, setup, and programming