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Home › Chevrolet › 2008 › Optra5 LS, Automatic › Repair and Diagnosis › Engine Performance › System › Engine Controls And Fuel - 1.8L (L79) › Diagnostic Information and Procedures › Ignition Relay Diagnosis › Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the main relay.
  2. Ignition ON, verify a test lamp illuminates between the relay coil ignition 1 voltage circuit terminal 86 and ground.
    • If the test lamp does not illuminate, repair the relay coil ignition 1 voltage circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect a test lamp between the relay coil control circuit terminal 85 and the relay coil ignition 1 voltage circuit terminal 86.
    • If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
  4. Ignition ON, the test lamp should turn ON.
    • 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. Connect a 15A fused jumper wire between the relay switch B+ supply circuit terminal 30 and the relay switch supply circuit terminal 87.
  6. Attempt to start the engine. The engine should start.
    • If the engine does not start, test the relay switch supply circuit between the main relay and the ECM for a short to ground or for an open/high resistance. If the circuit tests normal, replace the ECM.
  7. If all circuits test normal, test or replace the main relay.
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