Testing Coolant Temperature Sensors

I was wondering how I do the following:

1.) How to test the gauge and ecu coolant temperature sensors while they are in the thermostat stat housing using a multimeter. Exact settings on the multimeter is appreciated. I suspect my gauge sensor is toast.

2.) How do I test the wires that plug into these two sensors so I know they are still good? My logger showed varying temps while driving recently and I suspect faulty wiring or bad plug.

Thanks.

 

[s_firestone]

Here you go.

The Thermo Sensor is the one located at the bottom of the radiator near the middle. This is a thermal switch that toggles continuity at or above 183 degrees for the fan. I recommend if you intend to test this on the car, get a set of test leads you can clip on. I would not endorse reaching down that close to the manifold while the car is at operating temperatures and secondly because of the fan. I'm not sure what behavior the car will exhibit while this is unplugged(fan runs or no fan) so be careful.





The Coolant Temperature sensor and Gauge temperature sensor locations:





The Coolant Temperature sensor and Gauge temperature diagnostics. You can test these on the car.

 

Thank you very much.