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Hombre (4.3L)

  1. Perform On-Board Diagnostic II (OBD-II) System Check. See ON-BOARD DIAGNOSTIC II (OBD-II) SYSTEM CHECK in SELF-DIAGNOSTICS - INTRODUCTION article. After performing OBD-II system check, go to next step.
  2. If fuel pump runs continuously when key is off, go to step  26. If fuel pump does not run continuously when key is off, go to next step.
  3. Check for blown ECM B fuse (20-amp) located in underhood fuse block. If fuse is blown, go to step  21. If fuse is okay, go to next step.
  4. Connect TECH II scan tool to Data Link Connector (DLC). Turn ignition on and use scan tool to command fuel pump ON. Remove fuel filler cap and listen for fuel pump operation. If fuel pump can be heard, go to ENGINE CRANKS BUT WILL NOT RUN  under NO START DIAGNOSIS. If fuel pump can not be heard, go to next step.
  5. Remove fuel pump relay. Connect a fused jumper between fuel pump relay plug-in terminals No. 3 and 5 (Gray wire). If fuel pump can now be heard running, go to next step. If fuel pump can not be heard running, go to step  7.
  6. Connect test light between ground and fuel pump relay plug-in terminal No. 2 (Dark Green/White wire). If test light illuminates, go to step  8. If test light does not illuminate, go to step  9.
  7. Connect test light between ground and fuel pump relay plug-in terminal No. 3. If test light illuminates, go to step  10. If test light does not illuminate, go to step  11.
  8. Connect test light between battery positive terminal and fuel pump relay plug-in terminal No. 1 (Black wire). If test light illuminates, go to step  12. If test light does not illuminate, go to step  13.
  9. Check for an open or short circuit between fuel pump relay plug-in terminal No. 2 and PCM Black harness connector terminal No. 8 (Dark Green/White wire). Repair as necessary, then go to step  31. If no problem was found, go to step  14.
  10. Reinstall fuel pump relay. Unplug fuel pump wires at rear body harness connector. Connect test light between ground and fuel pump feed wire (body side of rear body harness connector). Use scan tool to command fuel pump ON. If test light illuminates, go to step  15. If test light does not illuminate, go to step  16.
  11. Repair open circuit between fuel pump relay plug-in terminal No. 3 and ECM B fuse (20-amp). Go to step  31.
  12. Replace fuel pump relay. Go to step  31.
  13. Repair open circuit between ground and fuel pump relay plug-in terminal No. 1 (Black wire). Go to step  31.
  14. Check for loose or corroded PCM harness connector terminals or connections. Repair as necessary, then go to step  31. If no problems were found, go to step  17.
  15. Connect test light between battery positive terminal and fuel pump ground circuit terminal at rear body harness connector (Black wire). If test light illuminates, go to step  18. If test light does not illuminate, go to step  19.
  16. Repair open or short circuit between fuel pump relay plug-in terminal No. 5 and fuel pump/sending unit (Gray wire). Go to step  31.
  17. Replace and reprogram PCM. See PROGRAMMING in SELF-DIAGNOSTICS - 4.3L article. Go to step  31.
  18. Check for open circuit in fuel pump power or ground wires between rear body harness connector and fuel pump. See ENGINE PERFORMANCE WIRING DIAGRAMS article. Repair as necessary, then go to step  31. If no problems were found, go to step  20.
  19. Repair open fuel pump ground circuit. See ENGINE PERFORMANCE WIRING DIAGRAMS article. Go to step  31.
  20. Replace fuel pump/sending unit assembly. See FUEL PUMP under FUEL SYSTEM in REMOVAL, OVERHAUL & INSTALLATION article. Go to step  31.
  21. Turn ignition off. Unplug fuel pump at rear body harness connector. Connect a test light between battery positive terminal and rear body harness connector fuel pump feed wire (Gray wire). If test light illuminates, go to next step. If test light does not illuminate, go to step  23.
  22. Repair short to ground between fuel pump relay and rear body harness connector fuel pump feed wire (Gray wire). See ENGINE PERFORMANCE WIRING DIAGRAMS article. Go to step  31.
  23. Connect a test light between battery positive terminal and fuel pump relay plug-in terminal No. 3. (ignition feed). If test light illuminates, go to next step. If test light does not illuminate, go to step  25.
  24. Repair short to ground between ECM B fuse (20-amp) and fuel pump relay plug-in terminal No. 3. (ignition feed). Go to step  31.
  25. Check for short to ground in fuel pump harness feed wire (Gray wire) on fuel pump side of rear body harness connector. Repair as necessary and go to step  31. If no problems were found, go back to step  20.
  26. Unplug fuel pump relay. If fuel pump stops running, go to next step. If fuel pump continues to run, go to step  30.
  27. Turn ignition off. Connect test light between ground and fuel pump relay plug-in terminal No. 2 (Dark Green/White wire). If test light illuminates, go to step  29. If test lights does not illuminate, go to next step.
  28. Replace fuel pump relay, then go to step  31.
  29. Check for short circuit to voltage on Dark Green/White wire between fuel pump relay plug-in terminal No. 2 and PCM Black connector terminal No. 1. See PIN VOLTAGE CHARTS article. Also see ENGINE PERFORMANCE WIRING DIAGRAMS article. Repair as necessary, then go to step  31.
  30. Check for short circuit to voltage on Gray wire between fuel pump relay plug-in terminal No. 5 and fuel pump. Repair as necessary, then go to step  31.
  31. Use scan tool to clear all DTCs. Attempt to start vehicle. If engine starts and stays running, go to next step. If engine does not start and stay running, go back to step  4.
  32. Allow engine to idle until normal operating temperature is reached. Use scan tool to determine if any undiagnosed DTCs are stored in memory. If there are, go to DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 4.3L article.
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