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INPUT DEVICE (SENSORS) TESTS
Temperature Tests
To test many components (such as radiators, transmissions, heaters, A/C condensers, A/C evaporators, engine
coolant sensors, coolant temperature switches, and air temperature sensors) that regulate temperature, measure
the surface temperature of the area surrounding the component.
Radiator
K type
Thermocouple
Meter setup to measure temperature:
• Set the rotary switch to temperature (TEMP) setting.
• Insert the plug of the K type thermocouple into the “COM” and “ ” jacks as shown, make sure that the
polarity connections are correct.
• Press the “REC” button (selects the MAX.MIN.AVG function).
Touch the tip of the thermocouple directly to the surface area near the radiator inlet.
Press the “DC/AC” button to switch between °F and °C.
Refer to the manufacturer’s specications for correct temperature. Measured temperature should be within
±10°F (±5°C) of the specications.
NOTE: The above procedure is specic to testing radiator temperature. Use similar test procedures to measure
temperature of other components or systems.
Two-Wire Device (Thermistor) Tests
Thermistors are essentially variable resistors that are sensitive to temperature level changes. The thermistor’s
resistance value changes as the temperature changes. Typical thermistor applications are: Engine Coolant
Temperature (ECT) sensor, Air Charge Temperature (ACT) sensor, Manifold Air Temperature (MAT) sensor, Vane
Air Temperature (VAT) sensor, and Throttle Body Temperature (TBT) sensor, etc.
A thermistor can be tested by checking resistance change or voltage change. A quel de Evaick and easy way to
monitor change is with the bargraph on the meter.
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