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Home › Chevrolet › 2006 › Optra LS, Standard › Repair and Diagnosis › Engine Performance › System › Engine Controls - 1.6L (L91) › Diagnostic Information and Procedures › DTC P0117 or P0118 › Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector of the ECT sensor.
  2. Ignition ON, verify that the ECT sensor parameter is at -40°C (-40°F).
    • If greater than -40°C (-40°F), test the signal circuit of the ECT sensor for a short to ground. If the circuit/connections test normal, replace the ECM.
  3. Test for less than 0.5 volt between the low reference circuit of the ECT sensor and ground.
    • If greater than 0.5 volt, test the low reference circuit of the ECT sensor for a short to voltage. If the circuit/connections test normal, replace the ECM.
  4. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the ECT sensor and ground.
    • If greater than 5 ohms, test the low reference circuit of the ECT sensor for an open/high resistance. If the circuit/connections test normal, replace the ECM.
  5. Install a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the ECT sensor and verify the ECT sensor parameter is greater than 128°C (262°F).
    • If less than 128°C (262°F), test the signal circuit of the ECT sensor for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
  6. If all circuits/connections test normal, test or replace the ECT sensor.
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