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Home >> GMC >> 1997 >> Forward Control 4.3 W, L35, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 11 (Engine Controls - Tests W/Codes - 7.4L (P Series)) >> Diagnostic Trouble Codes >> DTC P0441 - EVAP System No Flow During Purge >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. Perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the F - BASIC TESTING - 7.4L article. After performing OBD system check, go to next step.
  2. Install scan tool. Turn ignition on, with engine off. Using scan tool, command EVAP solenoid valve on and off while listening to solenoid valve. If solenoid valve turns on and off when commanded, go to next step. If solenoid valve does not turn on and off when commanded, go to step 5).
  3. Disconnect throttle body to EVAP solenoid valve vacuum hose. Install vacuum gauge to disconnected hose. Start engine. Allow engine RPM to stabilize at 2500 RPM. Momentarily snap throttle open and allow to return to idle. If 10 in. Hg vacuum is present at EVAP solenoid valve, go to next step. If 10 in. Hg vacuum is not present, go to step 7).
  4. Turn ignition off. Disconnect EVAP vacuum switch connector. Turn ignition on, with engine off. If scan tool indicates EVAP vacuum switch on, go to step 8). If scan tool does not indicate EVAP vacuum switch on, go to step 12).
  5. Turn ignition off. Disconnect EVAP solenoid valve connector. Turn ignition on, with engine off. Using test light, probe control circuit of EVAP solenoid valve connector to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step 9).
  6. Connect test light between EVAP connector terminals (engine harness side). Using scan tool, command EVAP solenoid valve on and off. If test light flashes on and off, go to step 10). If test light does not flash on and off, go to step 11).
  7. See DIAGNOSTIC AIDS.
  8. Check for pinched, kinked of clogged hoses to EVAP vacuum switch. If a problem was found, go to step 14). If a problem was not found, go to step 13).
  9. Repair open in EVAP solenoid valve ignition feed circuit. After repairs, go to step 16).
  10. Replace EVAP solenoid valve. After replacing EVAP solenoid, go to step 16).
  11. Check for open or short to voltage in EVAP solenoid valve control circuit. If a problem was found, go to step 14). If a problem was not found, go to step 15).
  12. Check for short to ground in EVAP vacuum switch signal circuit. If circuit is shorted, go to step 14). If circuit is okay, go to step 15).
  13. Replace EVAP vacuum switch. After replacing vacuum switch, go to step 16).
  14. Repair as necessary. After repairs, go to step 16).
  15. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
  16. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0441. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
  17. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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