Fuel Injector Circuit Tests
- Check Fuel Injector Operation - Using a stethoscope, ensure there are injector operating sounds 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 ECM Output Signal
- Turn ignition on. Backprobe listed ECM connector terminals to check voltage between ECM connector and ground. See ECM CONNECTOR TERMINAL IDENTIFICATION
table. If voltage is more than 10 volts, go to next step. If less than 10 volts are present, check for poor contact in ECM connector and repair harness or connectors as necessary. See appropriate wiring diagram in WIRING DIAGRAMS
article.ECM CONNECTOR TERMINAL IDENTIFICATION
ECM Terminal No. Application Cylinder No. 96 Ground 1 70 Ground 2 44 Ground 3 16 Ground 4 - Check Harness Between Fuel Injector & ECM Connector - Turn ignition off. Disconnect connector from faulty cylinder. Turn ignition on. Check voltage between listed ECM connector and ground on faulty cylinder(s). See ECM CONNECTOR TERMINAL IDENTIFICATION table. If voltage is more than 10 volts, repair battery short circuit in harness between ECM and fuel injector. After repair, replace ECM. If voltage is less than 10 volts, turn ignition off. Check resistance between fuel injector terminals No. 1 and 2 on faulty cylinder(s). See Fig 1 . If resistance is less than one ohm, replace faulty injector(s) and ECM. If resistance is more than one ohm, check for poor contact in ECM connector. Repair as necessary, replace ECM.