DTC Troubleshooting

DTC DIAGNOSTIC TROUBLESHOOTING CHART

Step	Action	YES	NO
1	Was "Engine and Emission Control System Check" performed?	Go to Step 2.	Go to ENGINE AND EMISSION CONTROL SYSTEM CHECK .
2	Engine coolant temp. check With ignition switch turned OFF, install scan tool. With ignition switch turned ON, check engine coolant temp. displayed on scan tool. (ECT1) Warm up engine to normal operating temp. Check engine coolant temp. displayed on scan tool. (ECT2) Is difference between ECT1 and ECT2 less than 1 °C (34 °F)?	Go to Step 4.	Go to Step 3.
3	Thermostat check Check thermostat referring to THERMOSTAT INSPECTION . Is thermostat in good condition?	Go to Step 4.	Faulty thermostat.
4	ECT sensor circuit check With ignition switch turned OFF, install scan tool and disconnect ECT sensor coupler. With ignition switch turned ON, check engine coolant temp. displayed on scan tool. ECT sensor circuit specifications (using scan tool) "GRN" wire terminal and "GRY/YEL" wire terminal are shorted: 164 °C (327 °F) "GRN" wire terminal and "GRY/YEL" wire terminal are opened: -40 °C (- 40 °F) Is each result satisfied its specification?	Go to Step 5.	Faulty "GRN" and/or "GRY/YEL" wire. If OK, substitute a known-good ECM and recheck.
5	ECT sensor performance check Check ECT sensor referring to ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION . Is check result as specified?	Intermittent trouble or faulty ECM. Check for intermittent referring to INTERMITTENT AND POOR CONNECTION INSPECTION .	Faulty ECT sensor.