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 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.
Reference Information
Schematic Reference
Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
* Component Connector End Views (Connector End Views By Name)
* Inline Harness Connector End Views (Diagrams)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
J 35616-200 - Test Light Probe Kit
Circuit/System Verification
Engine idling, observe the following control circuit status parameters for each fuel injector:
* Injector Ckt Short Gnd Test Status
* Injector Ckt Open Test Status
* Injector Ckt Short Volts Test Status
Each parameter should toggle between OK and Not Run or Not Run and OK.
Circuit/System Testing
1. Ignition OFF, disconnect the X101 fuel injector multi-way connector.
2. Ignition ON, verify that a J 35616-200 - Test Light illuminates between the ignition circuit terminal A ECM harness side 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 35616-200 - Test Light between the ignition circuit terminal A and the control circuit ECM harness side, of the appropriate injector listed below:
* Injector 1 terminal D
* Injector 2 terminal E
* Injector 3 terminal F
* Injector 4 terminal B
* Injector 5 terminal C
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 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. Ignition OFF, measure for 10-15 ohms on the engine harness side of X101 between the ignition circuit terminal A and the control circuit of the appropriate injector listed below:
* Injector 1 terminal D
* Injector 2 terminal E
* Injector 3 terminal F
* Injector 4 terminal B
* Injector 5 terminal C
• If the resistance is not within the specified range, test for a short to ground or an open/high resistance between X101 and the appropriate fuel injector harness connector. If the circuits test normal, test or replace the affected fuel injector.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Fuel Injector Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming