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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 370 (Engine Control System - Self-Diagnostics - 4.2L) >> Diagnostic Tests >> DTC P0440: Evaporative Emission Control System >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
  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 EVAP system for a loose, missing, or damaged service port Schrader valve, loose, incorrect, missing, or damaged fuel fill cap, or damaged EVAP purge solenoid. Raise and support vehicle on a hoist. Inspect the EVAP system for any disconnected, improperly routed, kinked, or damaged EVAP pipes and hoses, damaged EVAP vent solenoid or EVAP canister. Did you find and correct the condition? If yes, go to step  34. If no, go to next step.
  3. Clear the DTCs with a scan tool. Command the EVAP purge solenoid to 50 percent and back to zero percent with scan tool. Do you hear or feel a clicking from the EVAP purge solenoid when it is commanded to 50 percent? If yes, go to next step. If no, go to step  5.
  4. Command the EVAP vent solenoid ON and OFF with scan tool. Do you hear or feel a click as the EVAP vent solenoid is commanded ON and OFF? If yes, go to step  9. If no, go to step  7.
  5. Disconnect the EVAP purge solenoid. Turn ignition on, with engine off. Connect a test light between the ignition 1 voltage circuit of the EVAP purge solenoid and a known-good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  25.
  6. Connect a test light between the ignition 1 voltage circuit of the EVAP purge solenoid and the control circuit of the EVAP purge solenoid. Command the EVAP purge solenoid to 50 percent and then to zero percent with scan tool. Does the test light illuminate or pulsate when the EVAP purge solenoid is commanded to 50 percent and turn OFF when the EVAP purge solenoid is commanded to zero percent? If yes, go to step  20. If no, go to step  18.
  7. Turn ignition on, with engine off. Disconnect the EVAP vent solenoid. Connect a test light between the ignition 1 voltage circuit of the EVAP vent solenoid and a known-good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  26.
  8. Connect a test light between the ignition 1 voltage circuit of the EVAP vent solenoid and the control circuit of the EVAP vent solenoid. Command the EVAP vent solenoid ON, with scan tool. Does the test light illuminate? If yes, go to step  21. If no, go to step  19.
    9. NOTE: Ensure that vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. System flow will be less with higher temperatures.
  9. Turn ignition off. Connect Evaporative Emissions System Tester (J-41413-200) power supply clips to a known-good 12-volt source. Install the Fuel Tank Cap Adapter (J-41415-40) to fuel fill pipe. Connect fuel fill cap to the Fuel Tank Cap Adapter. Connect the nitrogen/smoke supply hose from the Evaporative Emissions System Tester to the Fuel Tank Cap Adapter. Turn ignition on, with engine off. Command the EVAP vent solenoid closed with a scan tool. Turn the nitrogen/smoke valve on the control panel to SMOKE. Use the remote switch to introduce smoke into the EVAP system. Use the EVAP Service Port Vent Fitting (J-41413-VLV) to open the EVAP service port. Remove the EVAP Service Port Vent Fitting once smoke is observed. Continue to introduce smoke into the EVAP system for an additional 60 seconds. Inspect the entire EVAP system for exiting smoke with the High Intensity White Light (J-41413-SPT). Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source? If yes, go to step  34. If no, go to next step.
  10. Disconnect the Fuel Tank Cap Adapter (J-41415-40) from the fuel fill pipe. Install fuel fill cap to fuel fill pipe. Connect the nitrogen/smoke supply hose to the EVAP service port. Use the remote switch to introduce smoke into the EVAP system. Inspect the entire EVAP system for exiting smoke with the High Intensity White Light (J-41413-SPT). Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source? If yes, go to step  34. If no, go to next step.
  11. Use the remote switch to stop introducing smoke. Install the Fuel Tank Cap Adapter (J-41415-40) to the fuel fill pipe. Connect the nitrogen/smoke supply hose to the Fuel Tank Cap Adapter. Connect fuel fill cap to the Fuel Tank Cap Adapter. Command the EVAP vent solenoid open with scan tool. Compare the Fuel Tank Pressure Sensor parameter with a scan tool, to the Pressure/Vacuum Gauge (J-41413-200). Is the scan tool Fuel Tank Pressure Sensor parameter within 1 in. H2O of the pressure/vacuum gauge? If yes, go to next step. If no, go to step  22.
  12. Seal the EVAP system using the EVAP Purge/Seal function on scan tool. Turn the nitrogen/smoke valve on the Evaporative Emissions System Tester control panel to NITROGEN. Use the Evaporative Emissions System Tester to pressurize the EVAP system to 10 in. H2O. Is the Fuel Tank Pressure Sensor parameter more than the 5 in. H2O? If yes, go to next step. If no, go to step  22.
  13. Use the remote switch to stop introducing nitrogen into the EVAP system. Increase the EVAP purge solenoid to 100 percent. Is the Fuel Tank Pressure Sensor parameter less than 1 in. H2O? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  14. Disconnect the EVAP purge vacuum source from the EVAP purge solenoid. Is the Fuel Tank Pressure Sensor parameter less than 1 in. H2O? If yes, go to step  24. If no, go to next step.
  15. Disconnect the EVAP purge pipe from the EVAP purge solenoid. Is the Fuel Tank Pressure Sensor parameter less than 1 in. H2O? If yes, go to step  29. If no, go to next step.
  16. Disconnect the EVAP purge pipe at the EVAP canister. Is the Fuel Tank Pressure Sensor parameter less than 1 in. H2O? If yes, go to step  27. If no, go to next step.
  17. Disconnect the EVAP vapor pipe at the EVAP canister. Is the Fuel Tank Pressure Sensor parameter less than 1 in. H2O? If yes, go to step  31. If no, go to step  28.
  18. Test the control circuit of the EVAP purge solenoid for an open or for a short to voltage. Did you find and correct the condition? If yes, go to step  34. If no, go to step  23.
  19. Test the control circuit of the EVAP vent solenoid for an open or for a short to voltage. Did you find and correct the condition? If yes, go to step  34. If no, go to step  23.
  20. Test for an intermittent and for a poor connection at the EVAP canister purge solenoid. Did you find and correct the condition? If yes, go to step  34. If no, go to step  29.
  21. Test for an intermittent and for a poor connection at the EVAP vent solenoid. Did you find and correct the condition? If yes, go to step  34. If no, go to step  30.
  22. Test for an intermittent and for a poor connection at the FTP sensor. Did you find and correct the condition? If yes, go to step  34. If no, go to step  32.
  23. Test for an intermittent and for a poor connection at the control module. Did you find and correct the condition? If yes, go to step  34. If no, go to step  33.
  24. Repair pinched or obstructed EVAP purge solenoid vacuum source. After repairs, go to step  34.
  25. Repair open or short to ground in the ignition 1 voltage circuit of the EVAP purge solenoid. Replace fuse as necessary. After repairs, go to step  34.
  26. Repair open or short to ground in the ignition 1 voltage circuit of the EVAP vent solenoid. Replace fuse as necessary. After repairs, go to step  34.
  27. Repair restriction in the EVAP purge pipe. After repairs, go to step  34.
  28. Repair restriction in the EVAP vapor pipe. After repairs, go to step  34
  29. Replace EVAP purge solenoid. After replacing solenoid, go to step  34.
  30. Replace EVAP vent solenoid. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. After replacing solenoid, go to step  34.
  31. Replace EVAP canister. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. After replacing EVAP canister, go to step  34.
  32. Replace FTP sensor. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. After replacing sensor, go to step  34.
  33. Replace PCM. See REMOVAL & INSTALLATION - BRAVADA, ENVOY, ENVOY XL, TRAILBLAZER & TRAILBLAZER EXT article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
    34. NOTE: Do not exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
  34. Connect the Pressure/Vacuum Gauge (J-41413-200) to fuel fill pipe. Turn the nitrogen/smoke valve to NITROGEN. Seal the EVAP system using the EVAP purge/seal function on scan tool. Pressurize the EVAP system to 5 in. H2O. Observe the pressure/vacuum gauge for 5 minutes. Does the pressure/vacuum gauge remain constant? If yes, go to next step. If no, go to step  2.
  35. Observe the stored information, Capture Info with scan tool. Does 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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