Fuel Injector Electrical Circuit Diagnosis

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.
NOTE: The fuel system wiring diagrams should be used in conjunction with the following test to correctly diagnose the problem.

Fuel Circuit Diagram:

Connector Identification:

1. Disconnect injectors 1, 2, and 3. Test for continuity between Electronic Control Unit (ECU) 24 pin connector (C517) terminal B1 and ground.
^ If there is continuity go to step 2.
^ If there is no continuity go to step 3.
2. Disconnect connector C104 and check for continuity between C517 terminal B1 and ground.
^ If there is continuity repair short to ground between C517 terminal B1 and C104 pin F7.
^ If there is no continuity repair short to ground between C104 pin F7, C525 pin A, C526 pin A, and/or C527 pin A.
3. Disconnect injectors 4, 5, and 6. Test for continuity between Electronic Control Unit (ECU) 24 pin connector (C517) terminal B2 and ground.
^ If there is continuity go to step 4.
^ If there is no continuity go to step 5.
4. Disconnect connector C104 and check for continuity between C517 terminal B2 and ground.
^ If there is continuity repair short to ground between C517 terminal B2 and C104 pin F8.
^ If there is no continuity repair short to ground between C104 pin F8, C528 pin A, C529 pin A, and/or C530 pin A.
5. If there is no continuity, test injector resistances with an ohmmeter. Injectors should have a resistance of 4-28 ohms.
^ If any injectors have a resistance outside this range, replace the injector(s) and test operation.
^ If all injector resistances are within specifications, the problem is computer related.