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How to use the basic measurement function of automobile digital multimeter?

Last Update Time: 2019-03-09 11:48:04

1.Proper use of basic measurement functions.

Automobile digital multimeter is an ideal instrument for detecting common electronic equipment of automobile, but it must be used correctly, and if it is not used properly, it can not get the correct data. The basic measuring function of automobile digital multimeter is described in Table 1 for reference.
Table 1. Use of basic measurement functions of a digital multimeter for automobiles.

Serial   number

Measuring   item

Measuring   method

1

Temperature   measuring method

(1)   Place the auto digital multimeter item selection switch in the temperature   (temp) block and press the function temperature (°c/f) button. (2) The black   wire tie-up (that is connecting GND), the probe plug into the temperature   measuring jack of the digital multimeter of the vehicle, and then the probe   end to be connected to the object to be measured, the number displayed on the   digital multimeter display is the temperature being measured.

2

Method   of measuring bandwidth-to-width ratio

(1).   Place the automotive digital multimeter item selection switch in the   bandwidth ratio (duty cycle) block. The black wire of the multimeter (i.e. connecting   GND), the red frequency-width ratio measurement method line and the signal   output end that need to measure circuit are put into the multimeter. (2)   Starting the engine to make it run, the frequency-to-width ratio of the pulse   signal can be displayed on the digital multimeter display screen of the   automobile.

3

Method   of speed measurement

(1).   Put the automotive digital multimeter item   selection switch in the rotational speed (RPM) gear. The special plug   for speed measurement is inserted into the iron seat hole and the common seat   hole, and then the auxiliary accessories of the digital multimeter are   sandwiched on the high-pressure ignition line of a certain cylinder of the   automobile engine. (2). Starting the engine to make it run, and observing the   automobile digital multimeter display screen can show the speed of the   engine.

4

Method   of measurement of starting current

(1).   Place the automotive digital multimeter item selection switch in the 400mv   (1mv equivalent to 1a current, where the starting current of the starter is   measured using a voltage measurement method). The   hall current sensor is sandwiched on the battery positive connection   wire, the lead is inserted into the multimeter current measuring jack, and   then the maximum / minimum function key of the digital multimeter is pressed.   (2). After removing the high-voltage conductor in the central socket of the   ignition coil (to ensure that the engine will not be started), the engine   crankshaft is driven by a starter to turn the crankshaft for 2-5 s. At this   time, the data displayed on the automobile digital multimeter display screen   is the starting current value.

 

5

Method   of measuring signal frequency

(1)   Put the automotive digital multimeter item selection switch in the frequency   (Freq) block. The black wire (connected to the ground wire) of the iron   socket of the digital multimeter, the red wire drawn from the public socket   hole of the digital multimeter and the detected signal line are put into the   black wire (connected to the ground wire) of the automobile digital   multimeter. (2). When the detected circuit is put into the working state, the   data displayed on the automobile digital multimeter display screen is the   measured frequency.

6

Method   of measuring the closure angle of the primary side circuit of the ignition   coil

(1).   Put the automotive digital multimeter item selection switch in the closed   angle (dwell) block. The black wire (connected to the ground wire) of the car   digital multimeter is connected to the negative pole of the ignition coil   from the common socket hole of the automobile digital multimeter, which is   connected with the black wire (connected to the ground wire) of the   automobile digital multimeter. (2). After starting the engine to make it run   smoothly, the data displayed on the digital multimeter display screen is the   closing angle of the primary circuit of the ignition coil.

7

Method   of measuring resistor

(1).   Put the automotive digital multimeter item selection switch in the appropriate   range of resistance (Ω) block, after correcting   the zero point of the meter, the resistor value can be measured. (2). The   short circuit and open circuit fault of electrical components and circuits in   automobile can find the fault location or cause by measuring resistor of   automobile digital multimeter. It must   be noted that the electrical resistor must not be measured on line in order   to prevent damage to the detection instrument.

8

Method   of measuring DC voltage

(1).   Put the automotive digital multimeter item selection switch at the   appropriate measurement range for the DC voltage (V) block, and two test pens   are connected to both ends of the measured circuit or component so that the   voltage value can be measured. (2). The method of DC voltage measurement can   be used to detect the point voltage, signal voltage, power supply voltage,   voltage drop on electrical components or parts of   automobile circuit, so as to determine the cause or the general   position of the fault.