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Home >> Chevrolet >> 2006 >> Optra LS, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 1.8L (L79) - DTC P0016 To DTC P0420 >> DTC P0201-P0204 >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector of the appropriate fuel injector.
    2. IMPORTANT: The test lamp is used to load the circuit and may not illuminate.
  2. Connect a test lamp between the ignition 1 voltage circuit of the fuel injector and ground.
  3. Ignition ON, test for less than 0.1 volt between the ignition 1 voltage circuit of the fuel injector and the battery voltage.
    • If greater than 0.1 volt, repair the ignition 1 voltage circuit of the fuel injector for a short to ground or an open/high resistance.
  4. With the ignition OFF, connect a J 34730-405  between the control circuit and the ignition 1 voltage circuit of the fuel injector.
  5. Engine running, the test lamp should flash.
    • If the test lamp remains ON all the time, test for a short to ground on the control circuit. If circuit/connections test normal, replace the ECM.
    • If the test lamp remains OFF all the time, test for a short to voltage or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM.
  6. If all circuits/connections test normal, test or replace the fuel injector.
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