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 P0261: Injector 1 Control Circuit Low Voltage
DTC P0262: Injector 1 Control Circuit High Voltage
DTC P0264: Injector 2 Control Circuit Low Voltage
DTC P0265: Injector 2 Control Circuit High Voltage
DTC P0267: Injector 3 Control Circuit Low Voltage
DTC P0268: Injector 3 Control Circuit High Voltage
DTC P0270: Injector 4 Control Circuit Low Voltage
DTC P0271: Injector 4 Control Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition 1 Voltage | P0261, P0264, P0267, P0270 | P0261, P0264, P0267, P0270 | -- | --
Injector 1 Control Circuit | P0261 | P0261 | P0262 | --
Injector 2 Control Circuit | P0264 | P0264 | P0265 | --
Injector 3 Control Circuit | P0267 | P0267 | P0268 | --
Injector 4 Control Circuit | P0270 | P0270 | P0271 | --

### Circuit/System Description

The engine control module (ECM) enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The ECM controls each fuel injector by grounding the control circuit via a solid state device called a driver. The ECM monitors the status of each driver.

### Conditions for Running the DTC

• | The engine is running.

• | The DTCs run continuously once the above conditions are met.

### Conditions for Setting the DTC

#### P0261, P0264, P0267, or P0270

The ECM detects the injector control circuit is open or shorted to ground.

#### P0262, P0265, P0268, or P0271

The ECM detects the injector control circuit is shorted to voltage.

### Action Taken When the DTC Sets

DTC P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271 are Type A DTCs.

### Conditions for Clearing the DTC

DTC P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271 are Type A 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

Fuel 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

#### Special Tools Required

J 34730-405 Injector Test Lamp

### Circuit/System Verification

1. Engine running, observe the DTC information with a scan tool. DTCs P0261, P0262, P0264, P0265, P0267, P0268, P0270, or P0271 should not set.
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 appropriate fuel injector.

Important: The test lamp is used to load the circuit and may not illuminate.

2. Connect a test lamp between the ignition 1 voltage circuit of the fuel injector and ground.
3. Ignition ON, load test for battery voltage between the ignition 1 voltage circuit of the fuel injector and ground.

⇒ | If less than B+, repair the ignition 1 voltage circuit of the fuel injector for a short to ground or an open/high resistance.

4. With the ignition OFF, connect a J 34730-405 between the control circuit and the ignition 1 voltage circuit of the fuel injector.
5. Engine running, the test lamp should flash.

⇒ | If the test lamp remains ON all the time, test for a short to ground on the control circuit. If circuit/connections test normal, replace the ECM.

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

6. If all circuits/connections test normal, test or replace the fuel injector.

### Component Testing

Important: The engine coolant temperature (ECT) sensor must be between 10-32°C (50-90°F) in order for an accurate measurement.

1. Measure for 13-16 ohms of resistance between the terminals of the fuel injector.

⇒ | If the resistance is not within the specified range, replace the fuel injector.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Fuel Injection Fuel Rail Assembly Replacement

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