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Home >> Pontiac >> 2002 >> Firebird Formula, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 5.7L >> Diagnostic Tests >> DTC P0412: Air Relay Control Circuit >> Diagnostic Procedures

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. Inspect the AIR pump fuse. Is the AIR pump fuse open? If yes, go to next step. If no, go to step  4.
  3. Disconnect the air solenoid connector. Test the battery voltage supply using a test lamp connected to battery voltage for a short to ground. Does the test lamp illuminate? If yes, go to step  13. If no, go to next step.
  4. Install a scan tool. Turn ON the ignition, with the engine OFF. Command the AIR solenoid ON and OFF with a scan tool. Does the AIR solenoid valve turn ON and OFF with each command? If yes, go to next step. If no, go to step  6.
  5. Review the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Attempt to duplicate the Freeze Frame/Failure Records data that you observed. Does the DTC reset? If yes, go to next step. If no, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  6. Turn OFF the ignition. Disconnect the AIR solenoid valve electrical connector. Turn ON the ignition, with the engine OFF. Probe the AIR solenoid valve battery voltage supply circuit with the Test Lamp (J 34142-B) connected to ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  13.
  7. Connect a test lamp between the control circuit of the AIR solenoid valve and the battery voltage supply circuit of the AIR solenoid valve. Command the AIR solenoid valve ON and OFF with a scan tool. Does the test lamp turn ON and OFF with each command? If yes, go to step  11. If no, go to next step.
  8. Does the test lamp remain illuminated with each command? If yes, go to step  10. If no, go to next step.
  9. Test the control circuit of the AIR solenoid valve for a short to voltage or an open. If you find a condition, repair the condition as necessary. Did you find and correct the condition? If yes, go to step  16. If no, go to step  12.
  10. Test the control circuit of the AIR solenoid valve for a short to ground. If you find a condition, repair the condition as necessary. Did you find and correct the condition? If yes, go to step  16. If no, go to step  12.
  11. Inspect for poor connections at the AIR solenoid valve. If you find a condition, repair the condition as necessary. Did you find and correct the condition? If yes, go to step  16. If no, go to step  14.
  12. Inspect for poor connections at the PCM. If you find a condition, repair the condition as necessary. Did you find and correct the condition? If yes, go to step  16. If no, go to step  15.
  13. Repair the battery voltage supply circuit between the AIR fuse and the AIR solenoid. After repairs, go to step  16.
  14. Replace the AIR solenoid valve. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  16.
  15. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  16. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC as specified in the supporting text. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  17. 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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