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Home >> Isuzu >> 2008 >> Ascender LS, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Engine Control System & Fuel System - 4.2L - DTC P0366 T0 DTC P2544) >> DTC P0443 or P0449 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2009 GMC Envoy and 2009 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the EVAP canister purge or vent solenoid valve.
  2. Ignition ON, verify that a test lamp illuminates between the voltage supply circuit terminal A and ground.
    • If the 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 purge solenoid.
  3. Connect a test lamp between the voltage supply circuit terminal A and the control circuit terminal B.
  4. Command the EVAP canister purge solenoid valve to 50 percent with a scan tool, or the EVAP canister vent solenoid valve ON and OFF. The test lamp should respond to the command.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
    • 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 ECM.
  5. If all circuits test normal, replace the appropriate solenoid valve.
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