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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 514 (Engine Controls/Fuel - Hybrid (LZ1) - DTC P0351 To DTC P3449 And Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> DTC P0443 or P0449 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2012 GMC Yukon, 2012 Chevrolet Tahoe, and 2012 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the following:
    • Q12 evaporative emission purge solenoid valve for P0443
    • Q13 evaporative emission vent solenoid valve for P0449
  2. Ignition ON, verify that a test lamp illuminates between the voltage supply circuit:
    • Terminal A and ground for the purge solenoid valve
    • Terminal B and ground for the vent solenoid valve
    • 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 all components connected to the voltage circuit and replace as necessary.
  3. Connect a test lamp between the voltage supply circuit and the control circuit.
  4. With a scan tool command the following:
    • EVAP purge solenoid valve to 50%
    • EVAP vent solenoid valve ON (Not Venting) and OFF (Venting)

      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 K20 Engine 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 K20 Engine Control Module.
  5. If all circuits test normal, replace the appropriate solenoid valve.
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