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Home >> Buick >> 2003 >> Century Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 3.1L Engine >> Diagnostic Tests >> DTC P0403: EGR Solenoid Control Circuit >> Diagnostic Procedure

Diagnostic Procedure

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Turn ignition switch to RUN position, engine OFF. Command the EGR from zero percent to 100 percent using a scan tool. Does the EGR Position Sensor parameter remain within 3 percent of the desired EGR position parameter when commanded using a scan tool? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, go to INTERMITTENTS in TROUBLE SHOOTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
  4. Turn ignition switch to OFF position. Disconnect the EGR valve. Turn ignition switch to RUN position, engine OFF. Probe the EGR solenoid high control circuit using a test light connected to a good ground. Command the EGR valve from 0-10 percent and from 10-0 percent using a scan tool. Does the test light turn ON at 10 percent and OFF at zero percent when commanded using a scan tool? If yes, go to next step. If no, go to step  6.
  5. Connect a test light between the EGR solenoid high control circuit and the EGR solenoid low control circuit. Command the EGR valve from 0-10 percent using a scan tool. Does the test light illuminate? If yes, go to step  10. If no, go to step  9.
  6. Does the test light remain illuminated when the EGR valve is commanded to zero percent using a scan tool? If yes, go to step  8. If no, go to next step.
  7. Test the EGR solenoid high control circuit for a short to ground or for an open. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  8. Test the EGR solenoid high control circuit for a short to voltage. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  9. Test the EGR solenoid low control circuit for an open or for high resistance. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  10. Test for an intermittent and for a poor connection at the EGR valve. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  11. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace the EGR valve. After repair, go to step  14.
  13. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repair, go to next step.
  14. Using a scan tool, clear the DTCs. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Does the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  15. Using the scan tool, observe the stored information in CAPTURE INFO. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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