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Home >> Pontiac >> 2001 >> Aztek Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0404: EGR Open Position Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. Turn ignition on. Using scan tool, check if DTC P0403 or P0405 is present. If DTC P0403 or P0405 is not present, diagnose affected DTC first. If DTC P0403 or P0405 is not present, select EGR OUTPUT CONTROL function. Increment EGR valve through all positions while comparing desired to actual EGR position. If desired and actual EGR position remains close to each other at all commanded positions, go to next step. If desired and actual EGR position is not within range, go to step  4.
  3. Using scan tool, review FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions and monitor SPECIFIC DTC info. If scan tool indicates that this DTC failed this ignition cycle, go to next step. If scan tool does not indicate that this DTC failed in this ignition cycle, see DIAGNOSTIC AIDS .
  4. Disconnect EGR valve harness connector. Check voltage between EGR harness connector terminals "B" (Black wire) and "D" (Gray wire). See Figure. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step  10.
  5. Using test light connected to battery voltage, probe EGR harness connector terminal "C" (Brown wire). If test light illuminates, go to step  8. If test light does not illuminate, go to next step.
  6. Using a fused jumper wire, jumper EGR harness connector terminals "C" (Brown wire) and "D" (Gray wire). Using scan tool, observe actual EGR position. If actual EGR position is 100 percent, go to step  9. If actual EGR position is not 100 percent, go to next step.
  7. Turn ignition off. Disconnect PCM harness connector. Check for open in Brown wire between EGR harness connector terminal "C" and PCM harness connector C2 terminal No. 28. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to step  15.
  8. Turn ignition off. Disconnect PCM harness connector. Using a test light connected to battery voltage, probe EGR harness connector terminal "C" (Brown wire). If test light illuminates, go to step  13. If test light does not illuminate, go to step  14.
  9. Turn ignition off. Check for poor terminal connections at EGR valve. Repair as necessary. After repairs, go to step  17. If terminal connections are okay, go to step  12.
  10. Turn ignition off. Check for open or short to ground in Gray wire between EGR harness connector "D" and PCM harness connector C2 terminal No. 30. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to next step.
  11. Check for open or short to voltage in Brown wire between EGR harness connector terminal "C" and PCM harness connector C2 terminal No. 28. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to step  15.
  12. Replace EGR valve. After replacing EGR valve, go to step  17.
  13. Turn ignition off. Locate and repair short to ground in Brown wire between EGR harness connector terminal "C" and PCM harness connector C2 terminal No. 28. After repairs, go to step  17.
  14. Check for short between Brown wire at EGR harness connector terminal "C" and PCM harness connector C2 terminal No. 28 and Black wire at EGR harness connector terminal "B" and PCM harness connector C1 terminal No. 31. See Figure. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to step  16.
  15. Check circuits related to EGR valve for poor terminal connection at PCM. Repair as necessary. After repairs, go to step  17. If circuits are okay, go to next step.
  16. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  17. Turn ignition on, with engine off. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0404. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, test is complete. If scan tool did not indicate that this test ran and passed, repeat step  2.
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