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 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 | * | ** | -- | --
Injector 1 Control Circuit | P0261, P0300 | P0261, P0300 | P0262, P0300 | --
Injector 2 Control Circuit | P0264, P0300 | P0264, P0300 | P0265, P0300 | --
Injector 3 Control Circuit | P0267, P0300 | P0267, P0300 | P0268, P0300 | --
Injector 4 Control Circuit | P0270, P0300 | P0270, P0300 | P0271, P0300 | --
* Engine cranks but does not run and the fuse for the injector circuit opens. ** Engine cranks but does not run.

### 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 ignition 1 voltage is between 7.5-16 volts.

• | 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

• | DTCs P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271 are Type B DTCs.

• | The ECM commands open loop fuel control.

### Conditions for Clearing the DTC

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

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component 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

Control Module References for scan tool information

#### Special Tools

J 34730-405 Injector Test Lamp

### Circuit/System Verification

Important: If you were sent here from Engine Cranks but Does Not Run, proceed to Circuit/System Testing.

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. 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, disconnect the harness connector at the appropriate fuel injector.
2. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit terminal A or 2 and ground.

⇒ | If the test lamp does not illuminate, repair the ignition 1 voltage circuit for a short to ground or an open/high resistance. Replace the fuse if necessary.

3. Ignition OFF, connect a J 34730-405 between the control circuit terminal B or 1 and the ignition 1 voltage circuit terminal A or 2.
4. Engine running, the test lamp should flash.

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

5. If all circuits test normal, test or replace the fuel injector.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the appropriate fuel injector.

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

2. Test for 11-14 ohms between the ignition 1 voltage terminal A or 2 and the control terminal B or 1.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Fuel Injector Replacement

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