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Home › Chevrolet › 2008 › Optra LS, Automatic › Repair and Diagnosis › Engine Performance › System › Engine Controls And Fuel - 1.8L (L79) › Diagnostic Information and Procedures › DTC P0660 › Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the IMT valve solenoid.
  2. Ignition ON, test for battery voltage between the ignition 1 voltage circuit terminal 2 and ground.
    • If less than B+, repair the ignition 1 voltage circuit for a short to ground or an open/high resistance. Replace the fuse, if necessary.
  3. Connect a test lamp between the control circuit terminal 1 and the ignition 1 voltage circuit terminal 2.
  4. Command the IMT valve solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF with the command.
    • If the test lamp is always ON, test the control circuit for a short to ground. If 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 circuit tests normal, replace the ECM.
  5. If all circuits test normal, test or replace the IMT valve solenoid.
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