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Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, open the hood to disable the Auto-Stop function.
  2. Ignition ON, verify the scan tool hood position parameter displays Open.
    • If the hood position does not display Open, refer to DTC P254F .
  3. Ignition OFF, disconnect the harness connector at the ECT sensor.
  4. Ignition OFF, remove the fuse that supplies B+ to circuit terminal X2-56 of the ECM.
    5. CAUTION: Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw.
  5. Test for less than 5 Ω between the low reference circuit terminal 2 and ground.
    • If greater than specified value, test the circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
  6. Install the fuse that supplies B+ to circuit terminal X2-56 of the ECM.
  7. Ignition ON, observe the scan tool the ECT sensor parameter. Verify that the ECT sensor parameter is at -40°C (-40°F).
    • If warmer than the specified value, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM.
    8. NOTE: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the ECT sensor may be damaged.
  8. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool ECT sensor parameter is warmer than 142°C (288°F).
    • If colder than the specified value, test the signal circuit for an open/high resistance or for a short to voltage. If the circuit/connections test normal, replace the ECM.
  9. If all circuits test normal, test or replace the ECT sensor.
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