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Home › Chevrolet › 2008 › Optra LS, Automatic › Repair and Diagnosis › Engine Performance › System › Engine Controls And Fuel - 2.0L (Diesel) › Diagnostic Information and Procedures › DTC P0627 › Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the fuel pump relay.
  2. Connect a test lamp between the control circuit terminal 86 and ground.
  3. Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
  4. Ignition OFF, connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 87.
  5. Ignition ON, command the fuel pump ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always OFF, repair the ground circuit for an open/high resistance.
  6. If all circuits test normal, test or replace the fuel pump relay.
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