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Home >> Chevrolet >> 2006 >> Optra LS, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 1.4L DOHC >> Diagnostic Information and Procedures >> DTC P0117 or P0118 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the engine coolant temperature (ECT) sensor.
  2. Ignition OFF, test for less than 5.0 ohms of resistance between the low reference circuit and ground.
    • If greater than 5 ohms, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, using a scan tool 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 tests normal, replace the engine control module (ECM).
    4. IMPORTANT: If the signal circuit of the ECT sensor is shorted to voltage the ECT sensor may be damaged.
  4. Install a 3-amp fused jumper wire between the signal circuit and the low reference circuit. 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 test normal, replace the ECM.
  5. If all circuits test normal, test or replace the ECT sensor.
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