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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 383 (Engine Controls - System & Component Testing - 3.4L) >> Fuel Systems >> Fuel Pump Electrical Circuit Diagnosis (Impala & Monte CARLO) >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. After performing diagnostic system check - engine controls, go to next step.
  2. Install a scan tool. Turn ignition switch to RUN position, engine OFF. Using the 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 circuit 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 fuel pump relay control circuit and the fuel pump relay ground circuit. Using a scan tool, command the fuel pump relay ON and OFF. Does the test light turn ON and OFF? 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  13.
  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. Is the fuel pump fuse open? If yes, go to step  27. If no, go to go to INTERMITTENTS in TROUBLE SHOOTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO 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 step 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. NOTE: Check the ground circuit for being tight, corrosion on terminals, or damage to the wiring harness.
  17. 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. Check 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. Check 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. Check for poor connections at the PCM harness connector. Did you find and correct the condition? If yes, go to step  27. If no, go to step  26.
  21. Repair the fuel pump supply voltage circuit 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 fuel pump relay switch battery voltage circuit. After repair, go to step  27.
    24. NOTE: Check 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 the PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE under PROGRAMMING in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
  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  2.
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