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Home >> Buick >> 2002 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.1L Engine >> Diagnostic Tests >> DTC P0116: ECT Sensor Circuit Performance >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Is the cooling system low on coolant? If yes, check and repair cause of loss of loss of coolant. If no, go to next step.
  3. Turn ignition off. Disconnect the ECT sensor. Connect a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the ECT sensor. Turn ignition on, with engine off. With a scan tool, observe the ECT sensor temperature. Does the scan tool indicate that the ECT sensor temperature is more than 280°F (138°C)? If yes, go to next step. If no, go to step  5.
  4. Turn ignition off. Disconnect the IAT sensor. Connect a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the IAT sensor harness connector. Turn ignition on, with engine off. With a scan tool, observe the IAT sensor temperature. Does the scan tool indicate that the IAT sensor temperature is more than 280°F (138°C)? If yes, go to step  8. If no, see DIAGNOSTIC AIDS .
  5. Turn ignition off. Disconnect the ECT sensor. Connect a 3-amp fused jumper wire between the signal circuit of the ECT sensor harness connector and a known-good ground. Turn ignition on, with engine off. With a scan tool, observe the ECT sensor temperature. Does the scan tool indicate that the ECT sensor temperature is more than 280°F (138°C)? If yes, go to next step. If no, go to step  7.
  6. Test the ECT sensor low reference circuit for a high resistance or an open. Repair the circuit as necessary. After repairs, go to step  11.
  7. Test the ECT sensor signal circuit for a high resistance or an open. Repair the circuit as necessary. After repairs, go to step  11.
  8. Remove ECT sensor. Suspend ECT sensor and a thermometer in a pan of water. Place pan on a burner or hot plate. Test resistance of ECT sensor through the specified range of 50-194°F (10-90°C). See appropriate SENSOR RESISTANCE table in appropriate SENSOR OPERATING RANGE CHARTS article. Does the resistance and temperature closely match? If yes, go to next step. If no, go to step  10.
  9. Reinstall ECT sensor. When complete, see DIAGNOSTIC AIDS .
  10. Replace ECT sensor. After replacing sensor, go to next step.
  11. Use the scan tool in order to clear the DTCs. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  12. Using scan tool, observe stored information and Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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