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Home >> Buick >> 2008 >> Allure CXS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 3.6L - DTC P0008 To DTC P0333 >> DTC P0125 or P0128 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the engine coolant temperature (ECT) sensor.
  2. Remove the fuse that supplies B+ to circuit terminal X2-36 of the engine control module (ECM).
  3. Test for less than 5 ohms between the low reference circuit terminal 2 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.
  4. Install the fuse that supplies B+ to circuit terminal X2-36 of the ECM.
  5. 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.
    6. IMPORTANT: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged.
  6. Ignition ON, connect 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 142°C (288°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.
  7. If all circuits test normal, test or replace the ECT sensor.
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