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Home › Buick › 2002 › Century Custom › Repair and Diagnosis › Engine Performance › System › Engine Control System Self-Diagnostics - 3.1L Engine › Diagnostic Tests › DTC P0443: EVAP Purge 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. Turn ignition on, with engine off. With a scan tool, command the EVAP purge valve to 50 percent and then to 0 percent. Do you hear or feel a clicking from the EVAP purge valve when the valve is commanded to 50 percent? If yes, go to next step. If no, go to step  4.
  3. Review 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 the DTC or as close to the Freeze Frame/Failure Records data that you observed. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn ignition off. Disconnect the EVAP purge valve harness connector. Turn ignition on, with engine off. Probe the ignition voltage circuit at the EVAP purge valve harness connector with a test light connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  11.
  5. Connect a test light between the control circuit and the ignition voltage circuit of the EVAP purge valve harness connector. With a scan tool, command the EVAP purge valve to 0 percent. Does the test light illuminate? If yes, go to step  8. If no, go to next step.
  6. With a scan tool, command the EVAP purge to 50 percent. Does the test light illuminate or pulse when the EVAP purge valve is commanded to 50 percent? If yes, go to step  9. If no, go to next step.
  7. Test the control circuit of the EVAP purge valve for an open or short to voltage. Did you find and correct the condition? If yes, go to step  14. If no, go to step  10.
  8. Test the control circuit of the EVAP purge valve for a short to ground. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  9. Inspect for poor connections at the harness connector of the EVAP purge valve. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  10. Inspect for poor connections at the harness connector of the control module. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  11. Repair the ignition voltage circuit of the EVAP purge valve. After repairs, go to step  14
  12. Replace the EVAP purge valve. 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. Use the scan tool in order to clear the DTCs. 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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