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Fuel Pump Electrical Circuit

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  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 appropriate SELF-DIAGNOSTICS article.
  2. Connect scan tool. Turn ignition on. Using scan tool, command fuel pump relay on and off. If fuel pump turns on and off, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article. If fuel pump does not turn on and off, go to next step.
  3. Using scan tool, command fuel pump relay on and off. If fuel pump relay clicks, go to step  9. If fuel pump relay does not click, go to next step.
  4. Turn ignition off. Disconnect fuel pump relay located in rear fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay control circuit at relay cavity. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to next step. If test light does not turn on and off, go to step  6.
  5. Connect test light between fuel pump relay control circuit and fuel pump relay ground circuit at relay cavities. Using scan tool, command fuel pump relay on and off. If test light turns on and off, go to step  19. If test light does not turn on and off, go to step  22.
  6. If test light remains illuminated with each command, go to next step. If test light does not illuminate at all, go to step  8.
  7. Disconnect PCM. Check for short to voltage in fuel pump relay control circuit. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to step  26.
  8. Disconnect PCM. Check for open or short to ground in fuel pump relay control circuit. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to step  20.
  9. Turn ignition on. If fuel pump runs continuously, go to next step. If fuel pump does not run continuously, go to step  11.
  10. Turn ignition off. Disconnect fuel pump relay located in rear fuse block. Turn ignition on. If fuel pump runs continuously, go to step  21. If fuel pump does not run continuously, go to step  25.
  11. Check F/PMP fuse (20-amp) located in rear fuse block. If fuse is open, go to next step. If fuse is okay, go to step  14.
  12. Remove fuel pump access panel. Check for short to ground in fuel pump power feed circuit between fuel pump and fuse. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to next step.
  13. Reconnect all components. Install NEW F/PMP fuse. Using scan tool, command fuel pump relay on. If fuse blows, go to step  24. If fuse does not blow, check for intermittent problem. See appropriate TROUBLE SHOOTING - NO CODES article.
  14. Turn ignition off. Disconnect fuel pump relay located in rear fuse block. Turn ignition on. Using test light connected to ground, probe fuel pump relay battery feed circuit at relay cavity. If test light illuminates, go to next step. If test light does not illuminate, go to step  23.
  15. Connect fused jumper wire between fuel pump relay battery feed circuit and fuel pump power feed circuit at relay cavities. If fuel pump runs, go to step  19. If fuel pump does not run, go to next step.
  16. Remove fuel pump access panel. Check for open or high resistance in fuel pump power feed circuit between fuel pump relay and fuel pump. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to next step.
  17. Check for open, high resistance or poor connection in fuel pump ground circuit at ground splice connector. Repair as necessary. After repairs, go to step  27. If circuit is okay, go to next step.
  18. Check for poor connections at fuel pump. Repair as necessary. After repairs, go to step  27. If connections are okay, go to step  24.
  19. Check for poor connections at fuel pump relay. Repair as necessary. After repairs, go to step  27. If connections are okay, go to step  25.
  20. Check for poor PCM harness connections. Repair as necessary. After repairs, go to step  27. If connections are okay, go to step  26.
  21. Repair short to voltage in fuel pump power feed circuit. After repairs, go to step  27.
  22. Repair open in fuel pump relay ground circuit. After repairs, go to step  27.
  23. Repair open in fuel pump relay battery feed circuit. After repairs, go to step  27.
  24. Replace fuel pump. After repairs, go to step  27.
  25. Replace fuel pump relay. After repairs, go to step  27.
  26. Replace PCM. Perform PCM relearn procedure. After repairs, go to next step.
  27. Operate system to verify repair. If system operation is okay, testing is complete. If system operation is not okay, go to step  2.
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