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Home >> Hummer >> 2009 >> H3 Base, Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls And Fuel - 3.7L - DTC P0013 To DTC P0315 >> DTC P0128 >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the ECT sensor.
  2. Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit terminal A and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, verify the scan tool ECT Sensor parameter is colder than -39°C (-38°F).
    • If warmer than the specified range, test the signal circuit terminal B for a short to ground. If the circuit tests normal, replace the ECM.
  4. Install a 3A fused jumper wire between the signal circuit terminal B and the low reference circuit terminal A. Verify the scan tool ECT Sensor parameter is warmer than 149°C (300°F).
    • If colder 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 the circuits test normal, test or replace the ECT sensor.
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