How to choose a car multimeter

Multimeter is a commonly used vehicle fault diagnosis tool. As the manufacturer of the multimeter tells you Automobile multimeters and ordinary multimeters are measuring instruments for electronic components. 

Automobile multimeters are developed for automobiles and can check data that ordinary multimeters related to automobiles cannot detect.

1.Car multimeter features: powerful, high accuracy, large internal resistance without threat to electronic components.

2.Automotive multimeters should generally have the following functions:

(1) Measure AC and DC voltage. Considering the allowable range of voltage fluctuations and possible overloads, automotive multimeters should be able to measure voltage values greater than 40V, but the measurement range should not be too large, otherwise the accuracy of the reading will decrease.

(2) Measure the resistance. Automotive multimeters should be able to measure 1MΩ resistance, and a larger measurement range is more convenient to use.

(3) Measure the current. Automotive multimeters should be able to measure currents greater than 10A, which is inconvenient to use even with a small measurement range.

(4) Memorize the maximum and minimum values. This function is used to check the transient fault of a circuit.

(5) Analog bar display. This function is used to observe continuously changing data.

(6) Measure the bandwidth ratio of the pulse waveform and the closing angle of the primary current of the ignition coil. This function is used to detect the working conditions of the injector, idling stability control valve, EGR solenoid valve and ignition system.

(7) Measure the rotation speed.

(8) Output a pulse signal. This function is used to detect the failure of the distributorless ignition system.

(9) Measure the electrical signal frequency output by the sensor.

(10) Measure the performance of the diode.

(11) Measure high current. After configuring the current sensor (Hall-type current sensing clip), it can measure high current.

(12) Measure the temperature. After the temperature sensor is configured, the cooling water temperature, exhaust gas temperature, and intake air temperature can be detected.

3.Notes on the use of digital multimeters

（1）If the magnitude of the measured voltage or current cannot be estimated in advance, it should be set to the highest range first and measured once.

Then gradually reduce the range to the appropriate position as appropriate. After the measurement is completed, set the range switch to the highest voltage range and turn off the power.

（2）At full scale, the meter only displays the number "1" in the highest digit, and the other digits disappear. At this time, a higher range should be selected.

（3）When measuring voltage, the digital multimeter should be connected in parallel with the circuit under test. When measuring the current, it should be connected in series with the circuit under test, and it is not necessary to consider the positive and negative polarity when measuring the direct current.

（4）When the AC voltage block is used to measure DC voltage, or the DC voltage block is used to measure AC power, the display will show “000”, or the lower digits will jump.

（5）It is forbidden to change the measuring range when measuring high voltage (above 220V) or high current (above 0.5A) to prevent arcing and burnout of switch contacts.