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Fuel Injector Circuit Diagnosis




Fuel Injector Circuit Diagnosis

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

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

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Programming and Relearning (Programming and Relearning)for scan tool information
Special Tools

J 44603 - Injector Test Lamp

Circuit/System Verification

1. Engine idling, observe the following control circuit status parameters for each fuel injector:

* Injector Control Circuit Low Voltage Test Status
* Injector Control Circuit Open Test Status
* Injector Control Circuit High Voltage Test Status
Each parameter should display OK or Not Run.

2. Engine running, observe the DTC information with a scan tool. DTCs P0201, P0202, P0203, or P0204 should not set.
3. 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 a fuel injector.
2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 and ground.

• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the fuel injector.

3. Ignition OFF, connect a J 44603 - Injector Test Lamp between the control circuit terminal 2 and the ignition circuit terminal 1 of each fuel injector one at a time.
4. Engine cranking, the test lamp should flash for each injector.

• If the test lamp is always ON, test the appropriate control circuit for a short to ground. If the circuit tests normal, replace the engine control module (ECM).

• If the test lamp is always OFF, test the appropriate 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. Refer to Fuel Injector Diagnosis (With J39021 or With Tech 2) (Fuel Injector Diagnosis (With J39021 or With Tech 2))Fuel Injector Diagnosis (With CH47976) (Fuel Injector Diagnosis (With CH47976)).

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Fuel Injector Replacement (Service and Repair)
* Programming and Relearning (Programming and Relearning)for replacement, setup, and programming

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