Is that a fault with the bus line? What are the causes of car line failures?

Automobile leakage refers to the phenomenon that the battery is gradually discharged when the car is stopped, which affects the difficulty of starting the car or the abnormal operation of electrical appliances. There are generally three types of causes of automobile leakage: the first is the battery power loss caused by the electrical switch is not turned off when parking, the second is the battery power loss caused by short circuit or oxidation and detachment of the battery plate, and the third type is the leakage caused by the electronic components and circuits such as automotive electrical appliances, wiring harnesses, sensors, controllers, actuators, etc.

Automobile leakage refers to the phenomenon that the battery is gradually discharged when the car is stopped, which affects the difficulty of starting the car or the abnormal operation of electrical appliances.

The so-called dark current (the reason why it is called dark current is because it is called dark current in English, so it is literally translated as dark current). It refers to the current that is still flowing when the ignition switch is in the off position (the car is not working) Because of the existence of these dark currents and the natural discharge of the battery, the battery capacity of the vehicle is insufficient when the vehicle is parked for a long time, resulting in the car being unable to start

So, why is there a dark current? First, some electrical equipment must be powered for a long time in order to maintain the memory function of the data, and these electrical appliances mainly refer to the computer control unit such as audio (remember the frequency band of the last time you listened, the track of the CD); There is also air conditioning (to remember the setting of wind direction and wind speed) Second, some anti-theft sensors require long-term power supply to ensure all-weather monitoring

The dark current of the general car is not more than 20mA, but the more advanced the car, due to the increase of electrical equipment, the dark current also increases At the same time, with the increase of automotive electrical equipment, as well as the increase of battery capacity, it seems that the dark current of the car will be larger and larger in the future Among the various faults of automobile maintenance, power loss (slip electricity) is an extremely common fault phenomenon, generally speaking, if the carburetor car (there are not many electronic control modules, and the power-consuming parts are relatively few), the power consumed naturally in about two weeks, There should be little effect on the starting (the battery itself has some self-discharge); If it is an electronically controlled car (because it has more electronic control modules and more power-consuming parts), generally speaking, if it does not start for a week or so, it may affect the normal start. If it falls below this time frame, it may be a malfunction, or the battery itself is faulty. In addition to the normal loss of electricity, there is another case:

If there is no leakage, then check the charging system of the car, sometimes if the charging line is not connected, it may cause the power to be fully charged into the battery, resulting in the peak of electricity consumption (summer night), the battery is in a state of semi-loss, and over time, there will be a phenomenon similar to leakage.

How to prevent the over-discharge of the battery caused by dark current is particularly important.

Note: The traditional leakage detection is to connect the multimeter in series to the negative electrode of the battery, and the lead wire of the battery needs to be removed. This is not only time-consuming and labor-intensive, but also easy to lose customer data (such as clocks and electronic navigation data, etc., which can easily cause customer dissatisfaction).

Hello 1Common faults in automobile circuits include open circuits, short circuits, leakage, and poor contact or poor insulation caused by loose wiring, moisture and corrosion. Open circuit: When there is an interruption at a certain point in the circuit from power to load.

Precautions should be taken for repairing line faults When replacing a burned out fuse, a fuse of the same specification should be used. The use of a fuse larger than the specified capacity can cause damage to the appliance or cause a fire.

When the electrical system fails, the phenomenon of the fault and the conditions under which the fault occurs should first be determined, so that the scope of the fault can be roughly determined.

Detection method of open circuit and poor contact fault As shown in the figure below, when a circuit break fault occurs in the line, the method of detecting resistance or voltage with a multimeter can be used to determine the location of the open circuit.

The most common reason why the battery is not working properly can be ruled out, look at it, thank you.

Hello according to your description, there are many reasons for the occurrence of circuit failures, if divided by the length of time, it can be divided into gradual failures and sudden failures, according to the use of equipment functions can be divided into destructive faults and functional faults, gradual faults are gradually formed, the fault is lighter at the beginning, and then a little bit stronger, the survival cycle is longer, and the causes of gradual failures are mostly friction and wear of parts. When the circuit is short-circuited or open-circuited, there will be sudden faults, destructive faults and functional faults, the former is that the electrical equipment has no ability to work, and the latter is the function of the electrical appliances is reduced, but it can still work. Hope mine is helpful to you, hope, thank you!!

For automotive line fault detection methods:

1. Compare the replacement method.

This is the most rigid, i.e., replacing the suspected faulty part with a new or working part, and checking whether the fault has changed or resolved.

For example, when the coolant temperature indication is abnormal in a car, and there is no diagnostic computer, we can use this method when we suspect that it is a problem with the water temperature sensor. If the abnormal temperature display disappears after replacing the new sensor, the original sensor is damaged. This method is simple, but it needs to be replaced by new or good accessories.

2. Listen to the sound inspection method.

It is a method of fault inspection through the sound condition (sometimes instantaneous) of some electrical assembly parts. For example, when we check the quality of a relay, we can listen to the sound of the relay. If there is a sound, it means that there is no problem with the control circuit of the relay.

Then we go to check the part of the line that is being controlled, which can shorten the maintenance time for us.

3. Test lamp inspection method.

Nowadays, there are more and more electronic devices in automobiles, and we should abandon the previous inspection method of scraping test and adopt test light inspection.

If the electronic control fan fails, when checking the thermal switch, one end of the test lamp can be connected to the power terminal, and the other end is connected to the iron, and the test light is on, indicating that the power supply is normal, and the fault may be in the thermal switch or fan relay, etc., if the test light is not on, the fan control circuit and safety device should be checked. The test light inspection is suitable for the power supply inspection of various electrical equipment and control circuits.

4. Short circuit inspection method.

That is, the wire is used to directly supply power to the electrical appliance. If the starter does not rotate, the "battery" post of the starter relay can be short-circuited with the wire, and the "starter" pillar, if the starter is running normally, the starter relay is damaged. In addition, the horn does not sound can also be checked by this method.

5. Section-by-paragraph inspection method:

If some of the car's longer circuits fail, they can be checked in several sections (combined with the "test light check" method) to find out the fault section.

6. Touch inspection method:

This is a method to check for faults by touching the contact parts of electrical appliances or circuits with your hands and feeling the difference in temperature. If the starter is running weakly, you can touch the temperature of the battery wiring part with your hands, if the temperature is very high, it means that the contact is poor. Also, touch the spark plug porcelain body with your hands (the engine works for about 10min and turns off), and the spark plug at a low temperature works poorly.

7. Instrument inspection method:

Hello Common faults are: broken skin between the cable and the frame and wire clamp due to vibration friction; Tail lights, brake lights, wires, etc. are broken due to vibration and friction; The installation of the lamp holder is loose or damaged due to vibration and damage to the connectors; When the vehicle is driving or parking, it will jump over the fire for a long time and produce high temperatures, causing insulation damage to electrical appliances, switches, and wires, thereby increasing the scope of the flashover, expanding the high temperature area, and finally leading to spontaneous combustion and fire in contact with paint, leaked gasoline, flammable materials, etc.

Hello, this wire should be installed later, as for the problems you said, it may be that this wire was originally connected to the fuse, it is recommended to check if there is a problem with the fuse.

It is recommended that if you are a repairman, it is recommended that you buy a circuit diagram of the corresponding model, and check the location of the problem according to the circuit diagram to find the common ground, so that you can know how the wire is connected. If you are the owner of the car, it is recommended that you go to the repair shop to have it checked, because the messy wiring may burn out other things.

1. Abnormal noise of the car.

2. Abnormal car performance due to car odor.

3. The working conditions of the car are abnormal.

4. The car overheats.

5. The exhaust smoke color is abnormal.

6. The appearance of the car is abnormal.

7. Abnormal driving of the car.

8. Car leakage.