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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 P0443 - EVAP Purge Solenoid Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Turn ignition on, with engine off. Using scan tool, command EVAP solenoid on and off. If solenoid turns on and off as commanded, go to next step. If solenoid does not turn on or off when commanded, go to step 5).
  3. Turn ignition off. Disconnect PCM harness connector containing solenoid control circuit. Turn ignition on. Using DVOM, set DVOM to 10-amp scale. Check current from solenoid control circuit in PCM harness connector to ground for 2 minutes. Current draw should be less than .75 amp, but not zero amps. If current draw is not as specified, go to next step. If current draw is as specified, see DIAGNOSTIC AIDS.
  4. Turn ignition off. Disconnect EVAP solenoid. Using DVOM, check resistance from solenoid control circuit in PCM harness connector and ground. Resistance should be infinite. If resistance is not as specified, go to step 12). If resistance is as specified, go to step 10).
  5. Turn ignition off. Disconnect EVAP solenoid. Connect test light between solenoid harness connectors. Turn ignition on. Using scan tool, command solenoid on and off. If test light turns on and off with each command, go to step 8). If test light does not turn on and off with each command, go to next step.
  6. Connect test light ground and probe the ignition feed circuit in the solenoid harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
  7. Turn ignition off. Reconnect EVAP solenoid. Disconnect PCM connector containing the solenoid control circuit. Turn ignition on. Using a fused jumper wire, jumper solenoid control circuit to ground in PCM harness connector. If solenoid operates, go to step 9). If solenoid does not operate, go to step 10).
  8. Check connections at EVAP solenoid. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 12).
  9. Check connections at PCM. Repair as necessary. After repairs, go to step 14). If connections are okay, go to step 13).
  10. Repair faulty EVAP solenoid control circuit. After repairs, go to step 14).
  11. Repair faulty EVAP solenoid ignition feed circuit. After repairs, go to step 14).
  12. Replace EVAP solenoid. After replacing solenoid, go to step 14).
  13. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to step 14).
  14. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0443. 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).
  15. 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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