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Home >> Chevrolet >> 2008 >> Optra LS, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 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 terminal 2 and ground.
    • If greater than the specified range, 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, verify the scan tool ECT sensor parameter is at -40°C (-40°F).
    • If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
    4. IMPORTANT: If the signal circuit of the ECT sensor is shorted to voltage the ECT sensor may be damaged.
  4. Install a 3A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool ECT sensor parameter is greater than 128°C (262°F).
    • If less than the specified range, test the signal 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 ECT sensor.
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