Engine Coolant Temperature (ECT) Sending Unit Test
- Turn ignition switch to OFF position. Ensure coolant level is correct and cooling system is operating properly. Disconnect Yellow/Green wire from ECT sending unit. Sending unit is located on intake manifold, near thermostat housing.
- Using a DVOM, measure resistance between ECT sending unit terminal and ground. With engine at about 133°F (56°C), resistance should be about 137 ohms. With engine at 185-212°F (85-100°C), resistance should be about 30-46 ohms. If resistance is considerably different than specified, replace ECT sending unit.