Basic methods for fault diagnosis and maintenance of electronic diesel injection system
May 30,2025
Basic methods for fault diagnosis and repair of electronic diesel injection system
In addition to traditional methods, the following methods can also be used when diagnosing and repairing faults.
(1) Comparison method
1 Working comparison method By judging whether the system (or component) is working, it is determined whether the system (or component) is damaged. For example, the cylinder disconnection method disconnects the injector connector of a cylinder to make the cylinder inoperative, so as to determine whether the cylinder is working properly.
2 Protection function method By using the failure protection function of the mechanical electronic control system, the sensor signal is disconnected (unplug the connection plug when the key switch is turned off), so that the electronic control system can work using the failure protection function, so as to determine whether the sensor is abnormal.
(2) Elimination method
Electronic control system failure may be caused by many reasons. Therefore, when troubleshooting, these influencing factors can be listed one by one according to the traditional method, and the method of gradually entering the actual part of the problem step by step is called elimination method.
(3) Reading fault code method
There are two ways to read fault codes: one is to read the fault code manually; the other is to use a fault diagnosis instrument to read the fault code. At present, most of the maintenance is to use the fault diagnosis instrument to read the fault code.
1 When performing fault code analysis, follow the steps below.
a. First read and record (printable) all fault codes.
b. Clear all fault codes.
c Confirm that the fault code has been cleared (when reading the fault code again, it should be displayed that there is no fault code at this time)
d. Simulate the conditions of the fault to conduct a road test to reproduce the fault.
e. Read and record the fault code at this time again.
f. Distinguish between intermittent (soft) fault codes and current (hard) fault codes.
g. Distinguish between fault codes related to fault symptoms and irrelevant fault codes.
h. Distinguish the main fault code among many fault codes or related fault codes (it may be the cause of other clapping).
According to the above analysis, further accurately check and measure the sensor, actuator or control unit represented by the fault code and the related circuit status to determine the exact location of the fault point.
2 The fault code indicates the electrical part controlled by the ECU, but cannot take into account (monitor) the mechanical part. By interpreting the fault code, most of the possible causes and locations of the fault can be correctly distinguished. Sometimes, misjudgment may occur, resulting in misleading results. In fact, a fault is only a yes or no conclusion, and it is impossible to point out the specific cause of the fault; if the fault location is to be determined, further analysis and inspection are required based on the fault phenomenon.
(4) Reading data stream method
The parameter values of some main sensors and actuators of the electronic control system during normal operation (such as speed, other voltages, air flow, injection time and coolant temperature, etc.) are combined according to different requirements to form a data stream or data block.
These standard data streams are provided by the manufacturer, or the fault self-diagnosis system records various relevant data during driving. When used, these data can be displayed on the display screen in the form of data through fault diagnosis, and the instantaneous values of the input or output of various sensors and actuators can be displayed on the display screen in the form of data. In this way, the various data changes during the mechanical working process can be compared with the data during normal driving (or standard data stream), and the cause of the fault of the electronic control system can be diagnosed.
(5) Waveform analysis method
The faults of the electronic control system are sometimes intermittent faults, which are sometimes present and sometimes absent, and it is difficult to analyze and judge them using data streams. In the electronic control system, many sensors and actuators use voltage, frequency or other digital forms to represent their signals. During the operation of the machine, it is difficult to find the problem from these constantly changing numbers because the signal changes very quickly. However, the waveform displayed by the oscilloscope can capture the small and intermittent changes in the fault. It compares the waveform diagram described by various sensor signals when the electronic control system is working normally with the waveform diagram when there is a fault. If there is an abnormality, it means that there is a problem with the control circuit or component of the signal itself. An oscilloscope must be used to read the signal of the electronic component, and some decoders also have an oscilloscope function.
From the damaged state to the repaired state, the waveform displayed on the oscilloscope almost always changes in its amplitude, frequency, shape, pulse width, and array. The oscilloscope uses a graph of voltage changing over time to reflect an electrical signal, and the electrical signal it displays is accurate and vivid. Some signals of electronic equipment change very quickly, with a change cycle of one thousandth of a second. Usually, the scanning speed of the test equipment should be 5 to 10 times that of the measured signal. Many fault signals are intermittent, sometimes appearing and sometimes not, which requires the test speed of the instrument to be higher than the speed of the fault signal. An oscilloscope can not only capture circuit signals quickly, but also display these waveforms at a slower speed. An oscilloscope can display the waveforms of all signal component voltages. Knowing how to analyze the waveform of component signal voltages and determine whether the waveform of this signal component voltage is normal, you can further check the faults of sensors, actuators, circuits, control units, etc. in the circuit, and you can also analyze the results after repairs.
Eligible models
MLT738 is the latest telescopic handler truck launched by our company. With its high-horsepower engine, MLT738 has surging power and strong passability. MLT738 can easily handle various tasks in agriculture. At the same time, we can provide a variety of auxiliary tools, such as large-capacity grain buckets, pitchforks, round bale clamps, etc. , one-stop solution to all customer problems.
WL08 is the best solution for working in narrow spaces and narrow passages. And with this machine and a large number of accessories related to road construction, agriculture, and horticulture, a considerable amount of work can be carried out.The entire vehicle is made of pure iron, which is particularly suitable for forest and outdoor forest operations such as wood grabbing.This machine has a small turning radius and fast driving speed, and can be deployed in buildings as well as on paved and unpaved sites.
WL10 is the best solution for working in narrow spaces and narrow passages. And with this machine and a large number of accessories related to road construction, agriculture, and horticulture, a considerable amount of work can be carried out.The entire vehicle is made of pure iron, which is particularly suitable for forest and outdoor forest operations such as wood grabbing.This machine has a small turning radius and fast driving speed, and can be deployed in buildings as well as on paved and unpaved sites.
Request a quote
Do you need any help? We are here to help!
To request a quote or find a local dealer, please fill out the form below. If you cannot find the product you need, please feel free to call +86 18366356399 or max@eougem.com Contact us and we will reply to you within 1 hour.
EOUGEM is a leading manufacturer of construction machinery in China, committed to producing high-quality medium and small loaders, hydraulic excavators, and various engineering mechanical deformation products.
Copyright © 2024 SHANDONG OUJIN ENGINEERING MACHINERY CO.,LTD. All rights reserved. SEO