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bmw m42 temperature gauge sensor voltage
It is best to use an oscilloscope to observe the signal voltage change of the engine coolant temperature sensor, because the multimeter can only see the voltage at one time point, and the oscilloscope can see the voltage change trend.
Start the car engine, then turn the oscilloscope time base to at least 50s, and adjust the vertical gear of the oscilloscope to make the waveform in the appropriate position in the screen. Turn on the low-pass filtering function of the oscilloscope. It is recommended that the low-pass frequency be 30kHz. Then wait for the waveform to change.
It can be seen that the waveform signal is a process of slowly falling and then rising. The engine coolant temperature sensor uses a thermistor that is sensitive to temperature changes. When the coolant temperature is low, the resistance of the sensor is large. When the coolant temperature rises, the resistance of the sensor will obviously decrease.
With this feature, the sensor can sense the change of the coolant temperature during actual use, and transmit the electrical signal to the ECU through the continuous conversion of the circuit, and the ECU will adjust it according to the input electrical signal.
Coolant sensor signal: as the temperature rises slowly, the bmw m42 temperature gauge sensor voltage drops slowly. When the voltage drops to 400mV, it can be seen that the cooling fan starts to work. At this time, the temperature drops again and the voltage begins to rise again. If you increase the time base and wait a little longer, you should see more obvious changes. The waveform can be used to analyze whether the coolant temperature sensor works normally and whether the fan works normally.
On the automobile, the signal voltage of the sensor is generally 5V or 5.5V, and the power supply voltage is 12V. It can be distinguished by measuring its resistance. The relay is divided into four pin type and five pin type. Generally, the replacement method is used to identify whether it is good or bad. The fault code shall be read with a special decoder.
The wire voltage of the automobile water temperature sensor is generally 5V. It supplies power for the computer version, and some voltages are 12V. The bmw m42 temperature gauge is equipped with warning lights and icons to prompt the user to check whether the battery voltage is normal, keep the battery within the normal range, etc., and protect the vehicle volume in many ways.
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