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Home › Saturn › 2003 › Ion 1 Automatic › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0116: Engine Coolant Temperature 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 coolant low? If yes, repair cause of coolant loss. If no, go to next step.
  3. Disconnect the ECT sensor. Connect a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the ECT sensor. Is the ECT sensor parameter more than 300°F (149°C)? If yes, go to next step. If no, go to step  5.
  4. Disconnect the Intake Air Temperature (IAT) sensor. Connect a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the IAT sensor. Observe the IAT sensor parameter with a scan tool. Is the IAT sensor parameter more 300°F (149°C)? If yes, go to step  8. If no, go to TEMPERATURE VS. RESISTANCE .
  5. Connect a 3-amp fused jumper wire between the signal circuit of the ECT sensor and a good ground. Is the ECT sensor parameter more than 300°F (149°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 for an open. Did you find and correct the condition? If yes, go to step  13. If no, go to step  9.
  7. Test the ECT sensor signal circuit for a high resistance or for an open. Did you find and correct the condition? If yes, go to step  13. If no, go to step  9.
  8. Test for an intermittent and for a poor connection at the ECT sensor. Did you find and correct the condition? If yes, go to step  13. If no, go to step  10.
  9. Test for an intermittent and for a poor connection at the ECM. Did you find and correct the condition? If yes, go to step  13. If no, see DIAGNOSTIC AIDS .
  10. Remove the ECT sensor. See ENGINE COOLANT TEMPERATURE SENSOR under SENSORS & SWITCHES in REMOVAL & INSTALLATION - ION article. Suspend the ECT sensor and a thermometer in a pan of water. Place the pan on a burner or hot plate. Test the resistance of the ECT sensor through the specified range of 50-194°F (10-90°C). Refer to TEMPERATURE VS. RESISTANCE . Does the resistance and temperature closely match the Temperature vs Resistance table? If yes, go to next step. If no, go to step  12.
  11. Install the ECT sensor. After installing sensor, go to DIAGNOSTIC AIDS .
  12. Replace the ECT sensor. After replacing sensor, go to next step.
  13. Using scan tool, clear DTCs. Turn ignition switch to OFF position for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  14. Observe the CAPTURE INFO using a scan tool. Are there any DTCs that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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