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Home >> Buick >> 2002 >> Century Custom >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.1L Engine >> Diagnostic Tests >> DTC P0403: EGR Solenoid Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

  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. Install a scan tool. Turn ignition on, with engine off. Command the EGR from 0-100 percent with a scan tool. Does 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 for this DTC. Turn ignition off for 30 seconds. Operate the vehicle within the Conditions for Running the DTC or as close as possible to the Freeze Frame/Failure Records that you observe. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition? If yes, go to next step. If no, go to INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn ignition off. Disconnect the EGR. Turn ignition on, with engine off. Probe the EGR valve high control circuit with a test light connected to a good ground. Command the EGR between 0-10 percent with a scan tool. 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. Command the EGR between 0-10 percent with a scan tool. 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 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 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. 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 Powertrain Control Module (PCM). Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace the EGR. After repairs, go to step  14.
  13. Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, 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 the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  15. Using scan tool, observe stored information and Capture Info. If scan tool displays any undiagnosed DTCs, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no other DTCs are displayed, system is okay.
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