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 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 | P0406 | P0404
Low Reference | -- | P0406 | -- | --

### 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%¹
EGR Position Sensor Signal | 0% | 0% | 99%¹
Low Reference | -- | 0% | --
¹ 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

• | Engine Control Module Connector End Views

• | Engine Controls 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

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### 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. 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 List.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the EGR valve.
2. Ignition ON, verify a test lamp illuminates between the ignition 1 voltage circuit 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 and B+.

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

4. Ignition ON, command the EGR valveON and OFF 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 circuit terminal and the control circuit terminal of the EGR valve.

⇒ | 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