Engine - Coolant Temperature Sensor/Switch: Testing and Inspection

WARNING: Removing the ECT switch while the engine is hot can cause the coolant to spray out, seriously scalding you. Always let the engine and radiator cool down before removing the ECT switch.

NOTE: Bleed air from the cooling system after installing the ECT switch.

1 Remove the ECT switch from the thermostat housing.





2. Suspend the ECT switch in a container of water as shown.
3. Heat the water, and check the temperature with a thermometer.

CAUTION: Do not let the thermometer touch the bottom of the hot container.





4. Measure the resistance between the A and B terminals according to the table.