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Home › Chevrolet › 2008 › Optra LS, Standard › Repair and Diagnosis › Engine Performance › System › Engine Controls And Fuel - 1.4L DOHC › Diagnostic Information and Procedures › DTC P0628 or P0629 › Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the fuel pump relay.
  2. Command the fuel pump relay ON with a scan tool. Test for battery voltage between the relay coil ignition 1 voltage circuit terminal 86 and ground.
    • If less than B+, repair the relay switch ignition 1 voltage circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect a test lamp between the relay switch control circuit terminal 85 and the ignition 1 voltage circuit terminal 86.
  4. Ignition ON, command the fuel pump relay ON with a scan tool. The test lamp should turn ON for about 3-5 seconds and then turn OFF.
    • If the test lamp is always ON, test the relay switch control circuit for a short to ground. If circuit tests normal, replace the ECM.
    • If the test lamp is always OFF, test the relay switch control circuit or 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 fuel pump relay.
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