Note. Before you troubleshoot, record all freeze data and any on-board snapshot, and review GENERAL TROUBLESHOOTING INFORMATION .
- Start the engine, and let it idle for 5 minutes or more.
- Check ECT SENSOR 1 in the DATA LIST with the HDS. Is about 0°F (-18°C) or less indicated? YES: Check for poor connection or loose terminals at ECT SENSOR 1, ECT SENSOR 2, and the ECM/PCM. If they are OK, replace ECT SENSOR 1 (see «ECT SENSOR 1 REPLACEMENT»(ref-320426-S22783962312009071400000) ). NO: Go to step 3 .
- Turn the ignition switch to LOCK (0).
- Allow the engine to cool to 104°F (40°C) or less.
- Make sure the difference between ECT SENSOR 1 and ECT SENSOR 2 is less than about 50°F (10°C) in the DATA LIST with the HDS.
- Start the engine, and let it idle until ECT sensor 1 goes up to about 158°F (70°C) Does the ECT sensor 2 also show about 158°F (70°C)? YES: Go to step 7 . NO: Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at ECT sensor 1, ECT sensor 2, and the ECM/PCM.
- Check the thermostat (see «FAN MOTOR TEST»(ref-320432-S19726163642009071400000) ). Is the thermostat OK? YES: Check for poor connection or loose terminals at ECT sensor 1, ECT sensor 2, and the ECM/PCM. If the connections and the terminals are OK, replace ECT SENSOR 1 (see «ECT SENSOR 1 REPLACEMENT»(ref-320426-S22783962312009071400000) ), then go to step 8 . NO: Replace the thermostat (see «THERMOSTAT REPLACEMENT»(ref-320432-S05913476082009071400000) ), then go to step 8 .
- Turn the ignition switch to ON (II).
- Reset the ECM/PCM with the HDS.
- Turn the ignition switch to LOCK (0).
- Allow the engine to cool to 104°F (40°C) or less.
- Check that the temperature difference between ECT SENSOR 1 and ECT SENSOR 2 is about 50°F (10°C) in the DATA LIST with the HDS.
- Start the engine, and let it idle until ECT sensor 1 goes up to about 158°F (70°C) Does the ECT sensor 2 also read about 158°F (70°C)? YES: Go to step 1 and recheck. NO: Troubleshooting is complete.