4 functions that are easily overlooked by the multimeter
(1) Frequency test
As long as the sensor can generate a frequency signal, it can be used for frequency testing with a multimeter. Such as intake pressure sensor and knock sensor. By making full use of the frequency test function of the multimeter, you can test the working status of the frequency signal sensor and judge the performance of the sensor.
(2) Duty cycle test
The duty cycle is a percentage value of the working time of a signal to the total time. Use a multimeter to test the duty cycle of the idle speed control valve and other components that adopt the duty cycle control method, and it can be determined that the idle speed control valve does not operate, the action is abnormal, and the action is inaccurate.
(3) Measurement of closing angle
The measurement of the dwell angle can find out the relevant reasons of the ignition failure, such as the contact distance of the distributor and the mechanical wear of the distributor. The method is as follows: ①Insert the black test lead into the COM jack, and the red test lead into the corresponding jack of the closed angle. ② According to the measured number of engine cylinders, set the function switch to the required "DWELL" range. ③Connect the black test lead to the iron or the negative pole of the battery, and the red test lead to the low-voltage terminal of the distributor or the negative pole of the ignition coil. ④Start the engine to read the dwell angle.
(4) Make good use of special functions
Some automotive multimeters have some special functions. For example, some multimeters have analog conversion modules (referred to as conversion modules), which have the functions of sensor signal simulation and driving actuators. If these functions are used properly, the efficiency can be greatly improved.
The multimeter can also play many other roles in maintenance, and there are still many to be discovered in practice. Only by continuously expanding and adopting new application methods in repair work can the maintenance efficiency be improved.
