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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 407 (Engine Controls - Basic Diagnostic Procedures - 3.1L) >> Fuel Systems >> Fuel Pump Electrical Circuit Diagnosis >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
  1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 3.1L CENTURY, GRAND PRIX & MALIBU article.
  2. Turn ignition switch to RUN position, engine OFF. Using a scan tool, command the fuel pump relay ON and OFF. Does the fuel pump turn ON and OFF? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  3. Using a scan tool, command the fuel pump relay ON and OFF. Do you hear a click when you command the fuel pump relay ON and OFF? If yes, go to step  9. If no, go to next step.
  4. Turn ignition switch to OFF position. Disconnect the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Probe the fuel pump relay control circuity using a test light connected to a good ground. Using a scan tool, command the fuel pump relay ON and OFF. Does the test light turn ON and OFF? If yes, go to next step. If no, go to step  6.
  5. Connect a test light between the control circuit of the fuel pump relay and the ground circuit of the fuel pump relay. Using a scan tool, command the fuel pump relay ON and OFF. Does the test light turn ON and OFF as commanded? If yes, go to step  19. If no, go to step  22.
  6. Does the test light remain illuminated with each command? If yes, go to next step. If no, go to step  8.
  7. Test the fuel pump relay control circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  27. If no, go to step  26.
  8. Test the fuel pump relay control circuit for a short to ground or an open. Did you find and correct the condition? If yes, go to step  27. If no, go to step  20.
  9. Turn ignition switch to RUN position, engine OFF. Does the fuel pump operate continuously? If yes, go to next step. If no, go to step  11.
  10. Turn ignition switch to OFF position. Disconnect the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Does the fuel pump operate continuously? If yes, go to step  21. If no, go to step  25.
  11. Is the fuel pump fuse open? If yes, go to next step. If no, go to step  14.
  12. Test the fuel pump supply voltage circuit for a grounded circuit between the fuel pump fuse and the fuel pump. Replace the fuel pump fuse if necessary. Did you find and correct the condition? If yes, go to step  27. If no, go to next step.
  13. Install all disconnected electrical components. Install a new fuel pump fuse. Using a scan tool, turn ON the fuel pump relay. Inspect the fuel pump fuse. Is the fuel pump fuse open? If yes, go to step  24. If no, go to INTERMITTENTS in TROUBLE SHOOTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
  14. Turn ignition switch to OFF position. Disconnect the fuel pump relay. Turn ignition switch to RUN position, engine OFF. Probe the fuel pump relay switch battery voltage circuit using a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  23.
  15. Connect a 20-amp fused jumper wire between the fuel pump relay switch battery voltage circuit and the fuel pump supply voltage circuit. Does the fuel pump operate? If yes, go to step  19. If no, go to next step.
  16. Test the fuel pump supply voltage circuit for an open or high resistance between the fuel pump relay and the fuel pump. Did you find and correct the condition? If yes, go to step. 27. If no, go to next step.
  17. Inspect the ground circuit for being tight, corrosion on terminals, or damage to the wiring harness. Test the fuel pump ground circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  27. If no, go to next step.
  18. Inspect for poor connections at the fuel pump. Did you find and correct the condition? If yes, go to step  27. If no, go to step  24.
  19. Inspect for poor connections at the fuel pump relay. Did you find and correct the condition? If yes, go to step  27. If no, go to step  25.
  20. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step  27. If no, go to step  26.
  21. Repair the supply voltage circuit of the fuel pump for a short to voltage. After repair, go to step  27.
  22. Repair the open fuel pump relay ground circuit. After repair, go to step  27.
  23. Repair the battery voltage circuit of the fuel pump relay switch. After repair, go to step  27.
    24. NOTE: Inspect for poor connections at the fuel pump, within the fuel tank, before replacing the fuel pump.
  24. Replace the fuel pump. Replace the fuel pump fuse if necessary. After repair, go to step  27.
  25. Replace the fuel pump relay. After repair, go to step  27.
  26. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE under PROGRAMMING in SELF-DIAGNOSTICS - 3.1L CENTURY, GRAND PRIX & MALIBU article. After repair, go to next step.
  27. 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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