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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 P1441 - EVAP System Flow During Non-Purge >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform Powertrain On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
    NOTE: DTC will set if vacuum lines at EVAP purge solenoid are reversed.
  2. 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 6).
  3. Start engine. Using scan tool, check EVAP vacuum switch status. If EVAP vacuum switch status changes to PURGE when engine is started, go to step 19). If EVAP vacuum switch status does not change to PURGE when engine is started, go to next step.
  4. Start engine and increase engine speed to 1500 RPM. Using scan tool, command EVAP canister purge solenoid on and off, while observing EVAP vacuum switch status. If scan tool indicates NO PURGE within 5 seconds, see DIAGNOSTIC AIDS. If scan tool does not indicate NO PURGE within 5 seconds, go to next step.
  5. Turn ignition off. Disconnect purge hose from EVAP vacuum switch. Start engine and increase engine speed to 1500 RPM. Using scan tool, command EVAP canister purge solenoid on and off, while EVAP vacuum switch status. If scan tool indicates NO PURGE within 5 seconds, go to step 11). If scan tool does not indicate NO PURGE within 5 seconds, go to step 12).
  6. Disconnect EVAP vacuum switch harness connector. Using test light connected to battery voltage, probe ground circuit at EVAP vacuum switch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
  7. Connect a fused jumper wire between EVAP vacuum switch harness connector terminals. If scan tool indicates EVAP vacuum switch NO PURGE, go to step 14). If EVAP vacuum switch does not indicate NO PURGE, go to next step.
  8. Using DVOM, check voltage at signal circuit of EVAP vacuum switch harness connector and ground. Battery voltage should be present. If battery voltage is present, go to step 18). If battery voltage is not present, go to next step.
  9. 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 16).
  10. Using DVOM, check continuity of EVAP vacuum switch signal circuit from vacuum switch harness connector to PCM connector. If resistance is less than 5 ohms, go to step 20). If resistance is greater than 5 ohms, go to step 17).
  11. Replace EVAP canister. After replacing canister, go to step 21).
  12. Repair restricted or kinked hose between canister and EVAP vacuum switch. After repairs, go to step 21).
  13. Repair open ground circuit. After repairs, go to step 21).
  14. Check connections at EVAP vacuum switch. Repair as necessary. After repairs, go to step 21). If connections are okay, go to next step.
  15. Replace EVAP switch. After replacing switch, go to step 21).
  16. Repair shorted signal to ground. After repairs, go to step 21).
  17. Repair open signal circuit. After repairs, go to step 21).
  18. Check connections at PCM. Repair as necessary. After repairs, go to step 21). If connections are okay, go to step 20).
  19. Replace EVAP canister purge solenoid. After replacing solenoid, go to step 21).
  20. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 16).
  21. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1441. 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).
  22. 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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