Fuel Injector Circuit Diagnosis

Fuel Injector Circuit Diagnosis

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* 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.


Circuit/System Testing

1. Remove the air cleaner outlet resonator.
2. Ignition OFF, disconnect a fuel injector.
3. Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit and ground.

• If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the INJECTORS IGN MOD fuse is open, test the fuel injectors. Refer to Fuel Injector Diagnosis (w/J39021 or w/Tech 2) Fuel Injector Diagnosis (w/CH47976). Fuel Injector Diagnosis (w/J39021 or w/Tech 2) Fuel Injector Diagnosis (With CH 47976)

4. Connect the J 44603 into each fuel injector connector one at a time.
5. Crank the engine. The test lamp should turn ON and OFF for each injector.

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

6. If all circuits test normal, test the fuel injectors. Refer to Fuel Injector Diagnosis (w/J39021 or w/Tech 2) Fuel Injector Diagnosis (w/CH47976). Fuel Injector Diagnosis (w/J39021 or w/Tech 2) Fuel Injector Diagnosis (With CH 47976)

Repair Instructions

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

Refer to Programming and Relearning for ECM setup and programming. Programming and Relearning