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Home › Cadillac › 2000 › Seville STS › Repair and Diagnosis › Engine Performance › System › Engine Control System - Self-Diagnostics - 4.6L › Diagnostic Tests › DTC P0404: EGR Open Position Performance › Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
    NOTE: If DTC P0403 or P0405 is set, diagnose affected DTC(s) first. See DTC P0403: EGR SOLENOID CONTROL CIRCUIT  or DTC P0405: EGR POSITION SENSOR CIRCUIT LOW VOLTAGE .
  2. Turn ignition on, with engine off. Using scan tool, select EGR VALVE OUTPUT CONTROL function. Increment EGR through all positions while comparing desired and actual EGR position. If desired EGR position remain close to actual EGR position at all commanded positions, go to next step. If desired EGR position does not remain close to actual EGR position at all commanded positions, go to step  4.
  3. Using scan tool, review and record FAIL RECORDS data. Operate vehicle within fail records conditions. Using scan tool, monitor SPECIFIC DTC INFO for this DTC until test runs. If scan tool indicates that DTC failed this ignition, go to next step. If scan tool does not indicate that this DTC failed this ignition, see DIAGNOSTIC AIDS .
  4. Disconnect EGR valve harness connector. Using a DVOM, check voltage between EGR pintle position sensor ground and 5-volt reference "A" circuits at harness connector. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step  10.
  5. Using a test light connected to battery voltage, probe EGR pintle position signal circuit at harness connector. If test light illuminates, go to step  8. If test light does not illuminate, go to next step.
  6. Connect a jumper wire between 5-volt reference "A" circuit and EGR pintle position signal circuit at harness connector. Using scan tool, observe actual EGR position. If scan tool indicates actual EGR position at 100 percent, go to step  9. If scan tool does not indicate actual EGR position at 100 percent, go to next step.
  7. Turn ignition off. Disconnect PCM harness connector. Check for open in EGR pintle position signal circuit. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to step  16.
  8. Turn ignition off. Disconnect PCM harness connector. Using a test light connected to battery voltage, probe EGR pintle position signal circuit. If test light illuminates, go to step  13. If test light does not illuminate, go to step  14.
  9. Check for poor connections at EGR valve. Repair as necessary. After repairs, go to step  17. If connections are okay, go to step  12.
  10. Check EGR 5-volt reference "A" circuit for short to ground or open between PCM and EGR valve. Repair as necessary. After repairs, go to step  17. If circuit is okay, go to next step.
  11. Check EGR pintle position sensor ground circuit for open or short to voltage. 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. Repair short to ground in EGR pintle position signal circuit. After repairs, go to step  17.
  14. Check EGR pintle position signal circuit for short to ground circuit. 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 connections at PCM. Repair as necessary. After repairs, go to step  17. If connections are okay, go to next step.
  16. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  17. Using scan tool, review and record FAIL RECORDS data. Clear DTCs. Operate vehicle within conditions for running this DTC. Using scan tool, select SPECIFIC DTC INFO for this DTC until test runs. If scan tool indicates that this DTC failed this ignition, go to step  2. If scan tool does not indicate that this DTC failed this ignition, system is okay.
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