Launch X431 GDS Manual page 27

LAUNCH X431 GDS Sensorbox Manual
Independent testing:
Unplug the wire connector of coolant temperature sensor, then
remove the sensor from the engine; place the sensor into a breaker
with water and heat the water, then use the "Resistance
measurement" to test the Resistance between two terminals of
coolant temperature sensor at different water temperature.
Compared the measured value with the standard value, if the
Resistance is not compliant with the standard, then the coolant
temperature sensor shall be replaced.
(2) Output signal voltage testing for coolant temperature sensor
After installing the coolant temperature sensor, plug the wire
connector of sensor, and then switch ignition ON, test the output
signal voltage between the two terminals of wire connector. The
tested voltage shall be in inverse proportional with the coolant
temperature. When the harness of coolant temperature sensor is
disconnected, the voltage shall be about 5V if the ignition switch is
ON.
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