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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> Engine Controls - System & Component Testing >> Fuel System (Gasoline) >> Fuel Pump Relay (All Except 2.2L & 3.0L VUE, 3.4L, 5.0L & 5.7L) >> Diagnostic Procedure

Diagnostic Procedure

  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Diagnostic System Check - Engine Controls, go to next step.
  2. Turn ON the ignition, with the engine OFF. Command fuel pump relay ON and OFF with a scan tool. Does fuel pump turn ON and OFF? If yes, go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - TRUCKS article. If no, go to next step.
  3. Command fuel pump relay ON and OFF with scan tool. Do you hear a click when you command fuel pump relay ON and OFF? If yes, go to step  9. If no, go to next step.
  4. Turn OFF the ignition. Disconnect fuel pump relay. Turn ON the ignition, with the engine OFF. Probe Control circuit of fuel pump relay with a test light that is connected to a good ground. Command fuel pump relay ON and OFF with scan tool. Does test light turn ON and OFF? If yes, go to next step. If no, go to step  6.
  5. Connect a test light between Control circuit of fuel pump relay and ground circuit of fuel pump relay. Command fuel pump relay ON and OFF with scan tool. Does test light turn ON and OFF? If yes, go to step  19. If no, go to step  22.
  6. Does test light remain illuminated with each command? If yes, go to next step. If no, go to step  8.
  7. Test Control circuit of fuel pump relay for a short to voltage. Did you find and correct condition? If yes, go to step  27. If no, go to step  26.
  8. Test Control circuit of fuel pump relay 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 ON the ignition, with the engine OFF. Does fuel pump operate continuously? If yes, go to next step. If no, go to step  11.
  10. Turn OFF the ignition. Disconnect fuel pump relay. Turn ON the ignition, with the engine OFF. Does fuel pump operate continuously? If yes, go to step  21. If no, go to step  25.
  11. Is fuel pump fuse open? If yes, go to next step. If no, go to step  14.
  12. Test supply voltage circuit of fuel pump for a grounded circuit between fuel pump fuse and fuel pump. Replace 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. With scan tool, turn ON fuel pump. Is fuel pump fuse open? If yes, go to step  24. If no, go to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - TRUCKS article.
  14. Turn OFF the ignition. Disconnect fuel pump relay. Turn ON the ignition, with the engine OFF. Probe battery voltage circuit of fuel pump relay switch with a test light that is connected to a good ground. Does test light illuminate? If yes, go to next step. If no, go to step  23.
  15. Connect a 20-amp fused jumper wire between battery voltage circuit of fuel pump relay switch and supply voltage circuit of fuel pump. Does fuel pump operate? If yes, go to step  19. If no, go to next step.
  16. Test supply voltage circuit of fuel pump for an open or high resistance between fuel pump relay and fuel pump. Did you find and correct the condition? If yes, go to step  27. If no, go to next step.
    17. NOTE: Inspect ground circuit for correct tightening, corrosion on terminals, or damage to wiring harness.
  17. Test ground circuit of fuel pump 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 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 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 harness connector of PCM. Did you find and correct the condition? If yes, go to step  27. If no, go to step  26.
  21. Repair supply voltage circuit of fuel pump for a short to voltage. After repairs, go to step  27.
  22. Repair open in ground circuit of fuel pump relay. After repairs, go to step  27.
  23. Repair open in battery voltage circuit of fuel pump relay switch. After repairs, go to step  27.
    24. NOTE: Inspect for poor connections at fuel pump, within fuel tank, before replacing fuel pump.
  24. Replace fuel pump. Replace fuel pump fuse if necessary. After repairs, go to step  27.
  25. Replace fuel pump relay. After repairs, go to step  27.
  26. Replace PCM. Perform PCM relearn procedures. See PROGRAMMING in appropriate SELF-DIAGNOSTICS article. After repairs, go to step  27.
  27. Operate system in order to verify repair. Did you correct the condition? If yes, system is okay. If no, go to step  2.
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