A car is a relatively complex system that includes a power take-off system, a walking system, a braking system, and an electrical system. The following is mainly to analyze and study the common fault diagnosis methods for automotive lighting in electrical systems.
1. The role and structure of automotive lighting systems
(1) The role of the lighting system
The safety of driving a car is very important. When driving in foggy weather and when the nighttime light is not good, there are different requirements for different lights. The combination of these lights is called the car light system. The car light system is an indispensable part of the car system.
(2) The structure of the lighting system
The car lighting system is a comprehensive component of the lighting and control switches in the car, mainly including the lighting device of the car, the lighting power supply and the lighting control part. The control system of an automotive lighting system mainly refers to the components of the lighting switch and electrical wiring.
2, common troubleshooting and troubleshooting
(1) The headlights are not lit
The cause of the malfunction: Under normal circumstances, the headlight of the car does not light. The reason may be that the fuse is too short due to the short-term power of the battery, causing the fuse to blow, or the power cord may be loose or loose, or it may be Poor contact of the connector or damage to the light control switch.
Troubleshooting method: For the case where the headlights are not lit, check the different procedures according to the specific conditions of the vehicle for diagnosis.
1 In the first case, one of the far-light and the close-up lights is not lit. At this time, it is first judged whether the filament is connected normally. If the filament is normal, the fuse is judged to be normal, and finally the line is checked.
2 The second case is that the far-light and the close-up lights are not bright. First check if there is a problem with the light control switch, then check if there is a problem with the filament, and finally check if there is any problem with the line.
(2) The front light is dim
The cause of the failure: the front light is dim, the normal brightness is not reached, the battery may be damaged, the power capacity is insufficient, the front control system voltage is low, or the generator is unable to work normally, the power generation is insufficient, and the output voltage is insufficient. Low; or the light caused by the dust of the car's lampshade glass can't be fired; or the filament is rusted, and the increase in resistance causes the filament to evaporate.
Troubleshooting method: Similarly, for the dim of the front light, different diagnostic methods should be performed according to the specific fault conditions of the car light.
1 In the first case, the illumination of a single bulb is not bright enough. First, determine whether the bulb that is not lit is dimmed by the filament or the bulb is not bright. Replace one bulb. If it is still, check the line.
2 The second case is that the light of a lamp is very dim. This situation is most likely caused by the dirty mirror surface of the mirror, or the power of the filament is too low, and then the line is checked if there is still a problem. .
(3) The front filament is often burnt out
Cause of failure: The main reason why the front filament is often burnt out may be because the line connection is not normal or the voltage regulator has a problem, causing the output voltage of the generator to the filament to be too high.
Diagnostic exclusion method: Check the car's charging system to check if the values ​​of the voltages are normal.
3. Common diagnostic methods for problems in automotive lighting systems
(1) Intuitive diagnostic method
Intuitive diagnosis means that after a problem occurs in the lighting system of a car, without first relying on any tools, the appearance is first observed, and the place where the problem occurs is determined by experience. Often, there are some external manifestations of problems with the car's electrical system. For the observation of the filament; see if there is a paste smell in the car due to abnormal current output, whether there is a spark, and a visual diagnosis of the fault can help find the problem as soon as possible.
(2) Test light diagnostic method
The test light is also a commonly used fault diagnosis method. This method can quickly and easily detect that the alternator is working properly, eliminate possible fault problems, and save time wasted by step by step.
(3) Open circuit diagnostic method
The open circuit diagnostic method is used to intercept part of the circuit experiment. It is enough to see that the light is not bright or the light is dim because the contact is not bright, and it can be solved for specific lamp path problems.
(4) Ground test fire diagnosis method
Ground test is a commonly used method in the process of circuit maintenance. It can determine the problem of the circuit and whether the generator is working properly according to the size and presence of the spark.
(5) Comparative diagnosis
The comparative diagnosis method refers to taking out the same type of accessories as the faulty problem for graft transfer. After the grafted device is connected, it is enough to ensure the normal operation of the car's lamp illumination system, so as to determine whether it is a problem, if the replacement is made, The lamp system works normally, indicating that an update of the device is required.
(6) Universal meter test method
The resistance value of the corresponding position is detected by the universal meter, and it is detected whether it is in the normal value interval to determine whether there is a problem.
(7) Short circuit diagnosis method
Take another wire or electrical appliance to connect the car's electrical appliances, and determine if there is a problem according to the corresponding changes. You can experiment with the turn signal and experiment with the turn signals of the left and right. The result is that if one light is on, it proves that there is a problem with the grounding. It needs to be managed and repaired. If both turn signals are on, it means there is no problem. The route here is good.
(8) Insurance diagnosis method
Under normal circumstances, there are two circuit safety devices installed in the car. If the current in the car is overloaded, it will cause automatic tripping of the car's main circuit and automatic power-off to automatically protect the car. Another device is a metal piece electric appliance, which can press the metal piece electric appliance to ensure that the car is always energized. At this time, it is checked which circuit has an overloaded battery carrying condition, and after the inspection is completed, the fuse is replaced. Disconnect the bimetal breaker.
4, the conclusion
The car lighting system is a relatively simple system among the four major systems of the car, but it also plays an important role. We must not only be familiar with its working principle, but also have a mastery and understanding of the common fault problems it generates so that we can In the event of a problem, you can find out the problem and solve the problem as soon as possible.
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