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Home >> Chevrolet >> 2008 >> Optra5 LS, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 1.4L DOHC >> Diagnostic Information and Procedures >> DTC P1476, P1477, or P1478 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the EGR solenoid.
  2. Command the fuel pump relay ON with a scan tool. 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.
  3. Ignition OFF, connect a test lamp between the control circuit terminal 1 and the ignition 1 voltage circuit terminal 2.
  4. Ignition ON, command the EGR solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF.
    • 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, test or replace the EGR solenoid.
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