How to use a Fluke multimeter for automotive maintenance
Perhaps the most commonly used automotive electrical repair tool is the multimeter. A general multimeter can test voltage, current and resistance. Specially developed multimeters such as Fluke's F78/F88/F98 have many functions specifically used for automotive testing, such as frequency, duty cycle, diode test, temperature, latch-up time (Dwell) and even engine speed (using accessories) wait.
This information introduces how to use Fluke's high-quality special multimeters and accessories for vehicle maintenance. The analog/digital combination of this watch has completely different advantages from other watches. Its accessories make maintenance more convenient and easier. Although multimeters have been used to repair cars for many years, most of them do not have special functions for car repairs. Computers and various sensors are widely used in today's cars, and a true multi-function multimeter is needed for car maintenance. The input impedance of the analog (pointer) multimeter used in the early days was too low, which had a great impact on the electronic circuit during measurement. This kind of meter mostly uses 9V voltage when testing resistance, so it can easily damage those sensitive electronic components. In recent years, new digital multimeters (DMMs) have been widely adopted.
Its input impedance is high, and its accuracy and accuracy are better than those of analog meters. The voltage when measuring resistance is also low (usually 5V, Fluke is 3.5V), so the components of each sensor will not be damaged. But there is also a problem with digital tables. It cannot display information on changes in measurement readings, such as increases or decreases. During exhaust emission testing and engine analysis, it will be found that a pure digital meter cannot give stable changing values.
Fluke overcomes the shortcomings of digital meters and replaces them with analog/digital combination meters. It has both the advantages of a digital meter and the dynamic measurement advantages of an analog meter.
Troubleshooting considerations
When troubleshooting the electrical part of a car, the most important thing is the reasoning process for the cause of the fault. This process is important. This is because you can't see what's going on inside and you can't take apart a large number of components like mechanical parts. Problems can be discovered quickly using logic and reasonable steps. The key tool in this process is the multimeter.
signal type
The signals tested mainly include voltage, current and resistance. But the most commonly used one is voltage. The questions involved are: Is there voltage? What is the voltage value? What should the normal value be? What is the voltage drop across components or junctions? For example, if the input voltage to a relay is 12.8V and it is 9.2V at the output, the voltage drop is 3.6V. Please note that the joints of the wires are considered components and will produce voltage drops. Therefore, it may cause malfunction.
