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Home >> Buick >> 2003 >> Century Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System Testing & Engine Component Tests - 3.1L >> Fuel Systems >> Fuel Injector Circuit Diagnosis >> Diagnostic Procedure

Diagnostic Procedure

  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.1L CENTURY, GRAND PRIX & MALIBU article. After performing diagnostic system check - engine controls, go to next step.
  2. Are any fuel injector DTCs set? If yes, go to DTC P0201-P0206: INJECTOR CONTROL CIRCUIT under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.1L CENTURY, GRAND PRIX & MALIBU article. If no, go to next step.
  3. Check the fuel injector fuse. Is the fuel injector fuse open? If yes, go to next step. If no, go to step  6.
  4. Turn ignition switch to OFF position. Disconnect the fuel injector multi-way harness connector. Probe the fuel injector ignition 1 voltage circuit, fuse side, using a test light connected to battery voltage. See Figure. Does the test light illuminate? If yes, go to step  9. If no, go to next step.
  5. Turn ignition switch to RUN position, engine OFF. Does the test light illuminate? If yes, go to step  13. If no, go to step  8.
  6. Turn ignition switch to OFF position. Disconnect the fuel injector multi-way harness connector. Turn ignition switch to RUN position, engine OFF. Probe the fuel injector ignition 1 voltage circuit, fuse side, using a test light connected to a good ground. See Figure. Does the test light illuminate? If yes, go to next step. If no, go to step  10.
  7. Check for continuity between the ignition 1 voltage circuit terminal and a fuel injector terminal, at the multi-way harness connector, fuel injector side. Does the DVOM display a resistance above 5 ohms? If yes, go to step  11. If no, go to step  12.
  8. Test the fuel injector ignition 1 voltage circuit, between the multi-way harness connector and the fuel injectors for a short to ground. Did you find and correct the condition? If yes, go to step  14. If no, go to DIAGNOSTIC AIDS .
  9. Repair the short to ground in the fuel injector ignition 1 voltage circuit. After repair, go to step  14.
  10. Repair the open in the ignition 1 voltage circuit between the Underhood Bussed Electrical Center (UBEC) and the multi-way harness connector. After repair, go to step  14.
  11. Repair the fuel injector ignition 1 voltage circuit for an open/high resistance, between the multi-way harness connector and the splice. After repair, go to step  14.
  12. Repair the poor connection at the multi-way harness connector. After repair, go to step  14.
  13. Repair the short to a PCM ground in the fuel injector ignition 1 voltage circuit. After repair, go to next step.
  14. Operate the system to verify the repair. Did you correct the condition? If yes, system is okay at this time. If no, go to step  3.
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