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Home >> Pontiac >> 2003 >> Aztek AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0403: EGR Valve Control Circuit >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Install a scan tool. Turn ignition on, with engine off. With a scan tool, command the EGR from zero percent to 100 percent. Does the EGR position sensor remain close to the Desired EGR Position at all commanded positions? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC or within the observed parameters of the Freeze Frame/Failure Records. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article.
  4. Turn ignition off. Disconnect EGR valve. Turn ignition on, with engine off. Probe the EGR valve high control circuit with a test light connected to a good ground. With a scan tool, command the EGR between 0-10 percent. Does the test light turn ON and OFF with each command? If yes, go to next step. If no, go to step  6.
  5. Connect a test light between the EGR valve high control circuit and the EGR valve low control circuit. With a scan tool, command the EGR between 0-10 percent. Does the test light turn ON and OFF with each command? If yes, go to step  10. If no, go to step  9.
  6. Does the test light remain illuminated with each command? If yes, go to step  8. If no, go to next step.
  7. Test the EGR valve high control circuit for a short to ground or 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 valve 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 valve low control circuit for an open or high resistance. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  10. Inspect for poor connections at the harness connector of the EGR valve. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  11. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace EGR valve. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. After repairs, go to step  14.
  13. Replace PCM. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  14. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to step  2.
  15. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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