Fuel Injector Electrical Circuit Diagnosis

FUEL INJECTOR TEST
NOTE: The following test procedure assumes that the ignition system is functioning, a good spark is present at the plugs, and that the FUEL SYSTEM DIAGNOSIS procedure has been followed to reach this procedure.
1. Ensure fuel pressure is within specifications.
2. Disconnect the injector wire connector from the fuel injector.
3. Place an ohmmeter across the fuel injector terminals. The resistance reading should be 16 ohms plus or minus 12 ohms at 20°C (68°F).
4. If there is infinite resistance, or the resistance reading is outside the listed specification, the injector is defective, and must be replaced.
FUEL INJECTOR CIRCUIT TEST

Fuel Circuit Diagram:

Connector Identification:

NOTE: The fuel system wiring diagrams should be used in conjunction with the following test to correctly diagnose the problem.
1. Using a logic probe or noid light, probe the back of the fuel injector electrical connector while turning the ignition switch to the "START" position.
^ If there is no signal (light does not flash), at the injector electrical connector, go to step 3.
^ If there is a signal present at the back of the connector go to step 2.
2. Unplug the injector connector and inspect for damaged or pushed out pins.
^ If connector pins are damaged or pushed out replace or repair as needed.
^ If pins are not damaged or pushed out go to step 3.
3. Remove the injector cap and inspect terminals for spreading or corrosion. Clean, repair or replace connector as needed. Connect a jumper across the injector cap terminals and check for continuity between the cap and the throttle body injector connector.
^ If there is continuity replace the fuel injector.
^ If there is no continuity, replace injector cap and wiring harness assembly.
4. Remove the fuel pump relay from its socket and test for continuity between terminal 87 (OG/BK wire) and the OG/BK wire of the injector connector.
^ If there is no continuity repair open in wiring and test operation.
^ If there is continuity go to step 5.
5. Disconnect 24 pin connector from the Electronic Control Unit (ECU), and inspect for corrosion, bent or pushed out pins, or spread connectors. Repair or replace any damaged terminals.
6. Test for continuity between cavity B1 of ECU connector C504 (light blue wire) and the light blue wire of the injector connector.
^ If there is no continuity repair open in wiring and test operation.
^ If there is continuity the problem is computer related.