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
DTC P0273: Injector 5 Control Circuit Low Voltage
DTC P0274: Injector 5 Control Circuit High Voltage
DTC P0276: Injector 6 Control Circuit Low Voltage
DTC P0277: Injector 6 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, P0273, P0276 | P0261, P0264, P0267, P0270, P0273, P0276 | -- | --
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 | --
Injector 5 Control Circuit | P0273 | P0273 | P0274 | --
Injector 6 Control Circuit | P0276 | P0276 | P0277 | --

### 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 speed is less than 6,400 RPM.

• | The ignition voltage is between 10-16 volts.

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

### Conditions for Setting the DTC

#### P0261, P0264, P0267, P0270, P0273, or P0276

The ECM detects the injector control circuit is open or shorted to ground for greater than 2 seconds.

#### P0262, P0265, P0268, P0271, P0274, or P0277

The ECM detects the injector control circuit is shorted to voltage for greater than 2 seconds.

### Action Taken When the DTC Sets

DTCs P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277 are Type A DTCs.

### Conditions for Clearing the DTC

DTCs P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277 are Type A DTCs.

### Diagnostic Aids

The fuel injector control circuits connect to the ECM through 2 different in-line harness connectors. Both connectors are located at the front of the engine under the intake manifold. Connector C-119 contains 3 fuel injector control circuits and the ignition 1 voltage circuit. Connector C-118 contains 3 fuel injector control circuits.

### 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

### Circuit/System Verification

1. Engine running, observe the DTC information with a scan tool. DTCs P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, or P0277 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

Important: The multi-way harness connectors, C118 and C119, are located under the intake manifold in front of the engine.

1. Ignition ON, observe the scan tool DTC information parameter. Verify that multiple fuel injector DTCs are not set.

⇒ | If multiple fuel injector DTCs are set, test the ignition 1 voltage circuit for a short to ground or an open.

2. Ignition OFF, disconnect the appropriate fuel injector multi-way harness connector.
3. Ignition ON, test for 3.4-4.4 volts between the appropriate control circuit and ground, on the ECM side of the multi-way harness connector.

• | Fuel Injector 1 terminal 4

• | Fuel Injector 2 terminal 5

• | Fuel Injector 3 terminal 6

• | Fuel Injector 4 terminal 1

• | Fuel Injector 5 terminal 2

• | Fuel Injector 6 terminal 3

⇒ | If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

⇒ | If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Ignition OFF, verify the resistance displays OL with a DMM between the appropriate control circuit and ground, on the fuel injector side of the multi-way harness connector.

• | Fuel Injector 1 terminal 4

• | Fuel Injector 2 terminal 5

• | Fuel Injector 3 terminal 6

• | Fuel Injector 4 terminal 1

• | Fuel Injector 5 terminal 2

• | Fuel Injector 6 terminal 3

⇒ | If less than the specified range, test the control circuit for a short to ground.

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

5. Test for 13-16 ohms of resistance between the appropriate control circuit and the ignition voltage circuit, on the fuel injector side of the multi-way harness connector.

⇒ | If greater than the specified range, test the control circuit for a short to ground or an open/high resistance.

⇒ | If less than the specified range, test for a short between the control circuit and the ignition voltage circuit.

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

### Component Testing

1. Ignition OFF, disconnect the appropriate fuel injector multi-way harness connector.

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

2. Test for 13-16 ohms of resistance between the control terminal and the ignition 1 voltage terminal.

⇒ | If 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 engine control module replacement, setup, and programming