I need a piece of advice about my temperature gauge. I want to determine what is wrong: my sensor or my gauge panel. I tried to disconnect sensor connector and connect it to new sensor, but gauge didn't move (it is below 0 angle), so I didn't change a sensor yet. Also, radiator fans are working normally. Can I use multimeter or something? Where to start? Thanks!
The key to understanding this system is that the signal to the gauge unit comes from the PCM not the temp sensor.
Testing is done at the connector at the PCM. Disconnect the “C” connector. Ground the C24 wire Y/G, turn the power on, Leave the ground connected for no more than 30 seconds. The gauge should move to Hot. If it does the gauge and wiring is OK.
Test the signal from the PCM by measuring the voltage at the computer it should be about 5 volts. Note this is actually a 5 volt square waveform that is best tested with an oscilloscope.
Care should be taken working in this area as expensive damage is possible if done wrong. Note that the the sensor is most likely OK if the check engine light is not on.
You should be able to do a resistance test on it to see how it's doing. Different resistance, different temp. Check it against the new one at the same temp. Should have the same value if good. You would be using a multimeter between the connections where the plug goes into the sensor (or however it's wired).
You will be able to get the datasheet of your sensor from the internet. With the help of a multimeter check the resistance of it at different temperatures. You will notice that the change in resistance per interval is greater than the last. The resistance change is not equal for every interval. The sensor is basically a thermister. (The radiator fan gets its signal from another sensor, basically a thermostat)