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 Descriptor

DTC P0261 00: Injector 1 Control Circuit Low Voltage
DTC P0262 00: Injector 1 Control Circuit High Voltage
DTC P0264 00: Injector 2 Control Circuit Low Voltage
DTC P0265 00: Injector 2 Control Circuit High Voltage
DTC P0267 00: Injector 3 Control Circuit Low Voltage
DTC P0268 00: Injector 3 Control Circuit High Voltage
DTC P0270 00: Injector 4 Control Circuit Low Voltage
DTC P0271 00: Injector 4 Control Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Fuel Injector Positive Voltage Control Group 1 | -- | P0201 00, P0204 00 | -- | --
Fuel Injector Positive Voltage Control Group 2 | -- | P0202 00, P0203 00 | -- | --
Fuel Injector 1 Control | P0261 00 | P0201 00 | P0262 00 | --
Fuel Injector 2 Control | P0264 00 | P0202 00 | P0265 00 | --
Fuel Injector 3 Control | P0267 00 | P0203 00 | P0268 00 | --
Fuel Injector 4 Control | P0270 00 | P0204 00 | P0271 00 | --

### Circuit/System Description

The engine control module (ECM) supplies voltage to each fuel injector on the injector positive voltage control circuits. The ECM energizes each fuel injector by grounding the control circuit of that fuel injector. The ECM monitors the status of the injector positive voltage control circuits and the fuel injector control circuits. The injectors are separated into the following two groups:

• | Group 1-Injectors 1 and 4

• | Group 2-Injectors 2 and 3

When a fuel injector circuit condition is detected by the ECM, the affected fuel injectors will be disabled and may disable the affected group of fuel injectors.

### Conditions for Running the DTC

• | The engine is running.

• | The ECM monitors for a condition once per camshaft revolution.

### Conditions for Setting the DTC

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match.

### Action Taken When the DTC Sets

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

### Conditions for Clearing the DTC

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

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### 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

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 are captured in the Freeze Frame/Failure Records Data List.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate fuel injector.
2. Ignition ON, test for 5.8-7.8 V between the low control circuit terminal 2 and ground.

⇒ | If less than the specified range, test the low control circuit for an open/high resistance or for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

⇒ | If greater than the specified range, test the low control circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Ignition ON, connect a test lamp between the affected fuel injector low control circuit terminal 2 and ground.
4. Engine cranking or running, the test lamp should illuminate or flash.

⇒ | If the test lamp does not illuminate or flash, replace the K20 Engine Control Module (ECM).

5. Ignition OFF, disconnect the harness connector X1 at the K20 Engine Control Module (ECM).
6. Ignition ON, test for less than 0.3 V between the high control circuit terminal 1 and ground.

⇒ | If greater than the specified range, test the high control circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

7. Ignition OFF, test for greater than 500 kΩ between the control circuit terminal 1 and ground.

⇒ | If less than the specified range, test the high control circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

8. Test for less than 5 Ω between the control circuit terminal 1 and the corresponding terminal of the injector

⇒ | If greater than the specified range, test the high control circuit for an open circuit. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

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

### Component Testing

1. Disconnect the harness connector at the appropriate fuel injector.

Note: The DMM and test leads must be calibrated to 0 Ω in order to prevent misdiagnosis.

2. Test for 0.2-0.3 Ω between the low control terminal 2 and the high control terminal 1.

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

3. Test for infinite resistance between each terminal and ground.

⇒ | If not the specified value, replace the fuel injector.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Fuel Injector Replacement

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