Fuel Injector Circuit Tests
- Check Fuel Injector Operation - Using a stethoscope, ensure that injector operating sound (clicking) is present while engine is cranking. If operating sounds are not heard, go to next step. If operating sounds are heard, verify fuel pressure. See FUEL PRESSURE under FUEL SYSTEM.
- Check Output Signal From ECM - Turn ignition on. Measure voltage between ECM connector terminals and ground on faulty cylinder. See ECM OUTPUT SIGNAL & FUEL INJECTION HARNESS IDENTIFICATION table. If voltage is less than 10 volts, go to next step. If voltage is more than 10 volts, check ECM connector for poor contact. If contact is okay, replace ECM.
- Check Resistance Of Harness Between Fuel Injector & ECM Connector - Turn ignition off. Disconnect fuel injector connector from faulty cylinder(s). Check resistance between fuel injector connector terminal No. 1 and ground. If resistance is less than 10 ohms, repair ground short circuit in harness between ECM and fuel injector. If resistance is more than 10 ohms, Check resistance of harness connector between ECM connector and fuel injector on faulty cylinders.
- Check Voltage Of Harness Between Fuel Injector & ECM Connector
- Turn ignition off. Disconnect fuel injector connector from faulty cylinder(s). Turn ignition on. Backprobe ECM connector terminals to ground. See ECM OUTPUT SIGNAL & FUEL INJECTION HARNESS IDENTIFICATION
table for terminal identification. If voltage is more than 10 volts, repair battery short circuit in harness between ECM and fuel injector and replace ECM. If voltage is less than 10 volts, go to next step.ECM OUTPUT SIGNAL & FUEL INJECTION HARNESS IDENTIFICATION
Terminal No. Cylinder No. 96 1 70 2 44 3 16 4 - Check Fuel Injector - Measure resistance between fuel injector terminals No. 1 and 2. See Fig 1 . If resistance is between 5 and 20 ohms, go to next step. If resistance is not between 5 and 20 ohms, replace fuel injector.
- Check Power Supply Line - Turn ignition on. Check voltage between fuel injector connector terminal No. 2 and ground on faulty cylinder. If voltage is more than 10 volts, repair poor contact in all connectors in fuel injector circuit. If voltage is less than 10 volts, repair open circuit in harness between main relay and fuel injector connector on faulty cylinders or possible poor contact in main relay or fuel injector connector.