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Home >> Oldsmobile >> 2000 >> Bravada >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 4.3L >> Diagnostic Tests >> DTC P0404: EGR Open Position Performance >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Start engine. Using scan tool, command EGR valve to 50 percent. If engine runs rough or stalls, go to next step. If engine does not run rough or stall, go to step  5.
  3. Turn ignition off, then turn ignition on, with engine off. Using scan tool, command EGR valve to 20, 50, 70, 100 percent. If actual EGR position follow the desired/commanded EGR position, go to next step. If actual EGR position does not follow the desired/commanded EGR position, go to step  10.
  4. This DTC is intermittent. Check for additional DTC(s) that are set. Diagnose affected DTC(s). If no other DTC(s) are set, see DIAGNOSTIC AIDS .
  5. Turn ignition off. Disconnect EGR harness connector. Turn ignition on, engine off. Using a test light connected to ground, probe EGR valve sensor harness connector control circuit. Using scan tool, command EGR valve to 100 percent. If test light illuminates, go to next step. If test light does not illuminate, go to step  7.
  6. Connect test light between battery voltage, probe EGR valve harness connector ground circuit. If test light illuminates, go to step  21. If test light does not illuminate, go to step  9.
  7. Check EGR valve control circuit for short to ground between VCM and EGR valve harness connector. Repair as necessary. After repairs, go to step  25. If circuit is okay, go to next step.
  8. Check EGR valve control circuit for open between VCM and EGR valve harness connector. Repair as necessary. After repairs, go to step  25. If circuit is okay, go to step  23.
  9. Check for open in EGR valve ground circuit. Repair as necessary. After repairs, go to step  25. If circuit is okay, go to step  23.
  10. Start engine. Using test light connected to ground, probe EGR valve control circuit at EGR valve harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  13.
  11. Turn ignition off. Disconnect VCM harness connector C4. Turn ignition on, with engine off. Using test light connected to ground, probe EGR valve control circuit. If test light illuminates, go to step  17. If test light does not illuminate, go to next step.
  12. Turn ignition off. With VCM harness connector C4 still disconnected, check EGR valve control circuit for short to all of other circuits in the C4 connector. If any circuits are shorted to EGR valve control circuit, go to step  18. If circuits are okay, go to step  24.
  13. Check voltage between ground and EGR valve harness connector 5-volt reference circuit. If voltage reading is greater than 5.2 volts, go to step  19. If voltage reading is not greater than 5.2 volts, go to next step.
  14. Check voltage between ground and EGR valve harness connector pintle position signal circuit. If voltage reading is zero volts, go to step  16. If voltage reading is not zero volts, go to next step.
  15. Check for short to voltage in EGR pintle position signal circuit between EGR valve harness connector and VCM. Repair as necessary. Repair as necessary. After repairs, go to step  25. If circuit is okay, go to step  24.
  16. Using test light connected to battery voltage, probe EGR sensor ground circuit at EGR valve harness connector. If test light illuminates, go to step  21. If test light does not illuminate, go to step  20.
  17. Repair the short to voltage in EGR valve control circuit. After repairs, go to  25.
  18. Repair short to EGR valve control circuit. After repairs, go to step  25.
  19. Repair short to voltage in 5-volt reference circuit. After repairs, go to step  25.
  20. Disconnect VCM harness connector C3. Check for open in EGR sensor ground circuit between VCM and EGR valve. Repair as necessary. After repairs, go to step  25. If circuit is okay, go to step  23.
  21. Check for poor connection at EGR valve connector. Repair as necessary. After repairs, go to step  25. If connection is okay, go to next step.
  22. Replace EGR valve. After replacing EGR valve, go to step  25.
  23. Check VCM harness connector for poor connection. Repair as necessary. After repairs, go to step  25. If connection is okay, go to next step.
  24. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
  25. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool did not indicate that this test ran and passed, repeat step  3.
  26. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. If no additional DTCs are set, system is okay.
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