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Home › Cadillac › 2006 › STS V › Repair and Diagnosis › Engine Performance › System › Engine Control System - 4.4L - DTC P0196 To P0496 › DTC P0449 › Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the EVAP canister vent solenoid valve.
  2. Ignition ON, verify that a test lamp illuminates between the voltage supply circuit terminal A and ground.
    • If a test lamp does not illuminate, test the voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal and the voltage supply circuit fuse is open, test or replace the EVAP canister vent solenoid valve.
  3. Connect a test lamp between the voltage supply circuit terminal A and the control circuit terminal B.
  4. Command the solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between commanded states.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the control module.
    • If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the control module.
  5. If all circuits test normal, replace the EVAP canister vent solenoid valve.
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