Talking about the common problems of using a digital multimeter to measure automotive circuits: If there is 12V or 5V at the terminal of the measuring wire harness, it is considered to be a wire bundle is good
Generally, the working voltage of the electrical equipment in the car is 12V. If an electrical equipment does not work normally, we will measure whether the power supply voltage on the connector of the electrical equipment is normal. For example, if the horn of a car does not sound, the maintenance technician usually unplugs the horn plug, presses the horn, and measures whether there is 12V between the power supply of the horn plug and the ground. This judgment is too hasty. The multimeter measures the voltage of the electromotive force, and the virtual voltage can also measure 12V. After testing, we found that if a 10-ohm resistor is connected in series in the circuit, the voltage is 5.94V, and it is replaced by 1K ohm. resistor, the voltage is still 5. 94V. If you use a high-power test lamp to measure the power supply and observe the brightness of the bulb, you can avoid being misled by virtual electricity.
