Fuel Injector Circuit Diagnosis

Fuel Injector Circuit Diagnosis

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview






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. Inspect the INJECTORS fuse.

^ If the fuse is open, repair the short to ground in the ignition 1 voltage circuit of the fuel injectors.

2. Remove the air cleaner outlet duct.
3. Disconnect a fuel injector.
4. With the ignition ON, engine OFF, probe the ignition 1 voltage circuit of the fuel injector with a test lamp that is connected to a good ground. The test lamp should illuminate.

^ If the test lamp does not illuminate, repair the open in the ignition 1 voltage circuit between the fuse and the splice.

5. Remove the INJECTORS fuse.
6. Measure the resistance between the INJECTORS fuse to the ignition 1 voltage circuit terminal of a fuel injector with a DMM. All wire circuit resistance should measure less than 2 ohms.

^ If the resistance is more than 2 ohms, repair the high resistance in the ignition 1 voltage circuit.

7. Connect the J 44603 into each fuel injector connector one at a time. Crank the engine.

^ If the test lamp flashes for each injector, perform the Fuel Injector Diagnosis. 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)
^ If the test lamp does not flash for each injector, test for an open or a short to voltage in the control circuit of the fuel injector, an intermittent or poor connection at the engine control module (ECM). If the circuit tests normal, replace the control module.
^ If the test lamp remains illuminated at all times for any injector circuit, test for a short to ground in the control circuit of the fuel injector. If the circuit tests normal, replace the control module.

Repair Instructions

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

Control Module References. Programming and Relearning