Circuit/System Testing
- Ignition OFF, disconnect the harness connector at a fuel injector.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 or A 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.
- Ignition OFF, connect a J 44603 between the control circuit terminal 2 or B and the ignition circuit terminal 1 or A of each fuel injector one at a time. See Special Tools .
- 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 engine control module (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.
- If all circuits test normal, test or replace the fuel injector. Refer to Fuel Injector Diagnosis (w/CH47976) or Fuel Injector Diagnosis (w/J39021 or w/Tech 2) or Fuel Injector Diagnosis (w/SA9182E or w/Tech 2) .