- Install scan tool. Start engine and check for DTCs. If DTC P0115 is present, go to next step. If DTC P0115 is not present, problem is intermittent. See INTERMITTENTS in «TESTS W/O CODES»(ref-16659) article.
- Turn ignition off. Disconnect ECT sensor harness connector. Using a DVOM, check continuity between sensor harness connector terminal No. 2 and ground. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-16646) article. If continuity is present, go to next step. If continuity is not present, check circuit between sensor harness connector and ECM.
- Turn ignition on. Using DVOM, check voltage between sensor harness connector terminal No. 1 and ground. DVOM should read 4.5-4.9 volts. If voltage reading is as specified, go to next step. If voltage reading is not as specified, check circuit between sensor harness connector and ECM.
- Turn ignition off. Reconnect ECT sensor harness connector. Start engine or turn ignition switch on. Using scan tool, check and record engine coolant temperature and resistance. See ECT SENSOR RESISTANCE SPECIFICATIONS table. If resistance is as specified, go to next step. If resistance is not as specified, replace ECT sensor.
- Check cooling system including thermostat. Replace as necessary. If cooling system is okay, clear DTC. See CLEARING CODES under Self Diagnostic System section. Retest system. If DTC does not reset, system is okay. If DTC resets, replace ECM.
| Coolant Temperature °F (°C) | Ohms |
|---|---|
| 32 (0) | 5900 |
| 68 (20) | 2500 |
| 104 (40) | 1100 |
| 176 (80) | 300 |
ECT SENSOR RESISTANCE SPECIFICATIONS