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Home >> Buick >> 1996 >> Roadmaster Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control Systems - Tests W/Codes >> Diagnostic Trouble Codes >> DTC P0441 - EVAP System No Flow During Purge >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. If DTC P0443 is present, diagnose this DTC first. Turn ignition on, with engine off. Using scan tool, check EVAP vacuum switch status. If scan tool indicates that EVAP vacuum switch is not purging, go to next step. If scan tool indicates that EVAP vacuum switch is purging, go to step 5).
  3. Start engine. Using scan tool, command EVAP canister purge solenoid on, while observing EVAP vacuum switch status. If scan tool indicates that canister is purging when solenoid is commanded on, see DIAGNOSTIC AIDS. If solenoid is not purging when commanded on, go to next step.
  4. Turn ignition off. Disconnect purge hose from EVAP vacuum switch. Connect a vacuum gauge to canister side of EVAP switch. Start engine. Using scan tool, command EVAP canister purge solenoid on, while observing vacuum gauge. If vacuum gauge indicates vacuum reading close to engine vacuum when solenoid is commanded on, go to next step. If vacuum reading is close to engine vacuum, go to step 7).
  5. Disconnect EVAP vacuum switch harness connector. If scan tool indicates PURGE, go to step 9). If scan tool does not indicate PURGE, go to next step.
  6. Turn ignition off. Disconnect PCM connector C2. Using DVOM, check continuity between EVAP vacuum switch signal circuit and ground. If DVOM reads infinity, go to step 10). If DVOM does not read infinity, go to step 12.
  7. Disconnect vacuum harness from EVAP canister purge solenoid and connect vacuum gauge to manifold side of vacuum harness. If normal manifold vacuum is indicated, go to next step. If manifold vacuum is not indicated, go to step 13).
  8. Rotate vacuum harness connector enough to reconnect only the manifold vacuum supply hose to solenoid. Connect vacuum gauge to the other port on solenoid. Using scan tool, command EVAP canister purge solenoid on, while observing vacuum gauge. If vacuum is indicated when solenoid is commanded on, go to step 14). If vacuum is not indicated when solenoid is commanded on, go to step 15).
  9. Replace EVAP vacuum switch. After replacing vacuum switch, go to step 16).
  10. Check connections at PCM. After repairs, go to step 16).
  11. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 16).
  12. Repair signal circuit shorted to ground. After repairs, go to step 16).
  13. Check for blocked or restricted manifold vacuum port. Check for kinked or leaking hose between EVAP solenoid and intake manifold. Repair as necessary. After repairs, go to step 16). If vacuum port and vacuum lines to affected components are okay, go to next step.
  14. Check for restricted, kinked or leaking hose between EVAP solenoid and vacuum switch. After repairs, go to step 16).
  15. Replace EVAP solenoid. After replacing solenoid, go to next step.
  16. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0441. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool did not indicate that this test ran and passed, repeat step 2).
  17. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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