What are the basic functions of the automotive fault self diagnosis system?

Function. 1. Find faults.

If a signal outside of the normal range is fed into the microprocessor, the ECU will diagnose that the signal system is in an abnormal state. For example, the engine cooling water temperature signaling system specifies that the voltage of the sensor is normal and that an abnormality is diagnosed outside of this range.

If the microcomputer itself fails, it is monitored by a time-limited circuit equipped with an emergency monitoring timer; If there is a program abnormality, the resetting of the time-limited circuit that is carried out periodically stops working, so that the fault detection method of microcomputer resetting can be adopted.

2. Fault classification.

When the microcomputer is working normally, the abnormal condition of the input signal is detected by the diagnostic program, and then according to the detection results, it is divided into minor faults that do not cause obstacles, faults that cause functional degradation, and major faults. And the fault is classified according to importance, in advance in the program, when the microcomputer itself fails, the major fault classification is carried out through WDT.

3. Fault alarm.

Generally, the owner of the car is alerted by the flashing of the warning light set on the dashboard. In cars equipped with displays, there are also cases where the alarm content is displayed directly in text.

4. Fault storage.

When a fault is detected, the fault site is stored in the memory, and under normal circumstances, even if the ignition switch is in the disconnected position, the power supply of the microcomputer and the storage part remains on without causing the loss of stored contents. Only when the battery is disconnected or the fuse is unplugged, the fault in the memory** is automatically eliminated due to the power cut off from the microcomputer.

5. Troubleshooting.

If a failure occurs during the operation of the car, in order not to hinder the normal driving, it is regulated by the microcomputer, and the surrogate value in the pre-programmed program is used to calculate to maintain the basic driving performance, and then the corresponding maintenance is carried out by the owner or maintenance personnel after the stop.

The automotive self-diagnosis system includes a special vehicle detector, a vehicle-mounted diagnostic system, and a multi-functional vehicle-mounted external diagnostic system.

Generally, cars equipped with microprocessor control units have fault self-diagnosis systems. It can be used to automatically check and monitor the working status of each part of the transmission system and control system in the car.

When a sensor or circuit fails:

Its signal can no longer be used as the control parameter of the car, in order to maintain the operation of the car, the fault self-diagnosis module calls up the preset experience value from its program memory, as the emergency input parameter of the circuit, to ensure that the car can continue to work.

Hello There are functions such as fault discovery, fault classification, fault alarm, fault storage, fault handling, etc. When the car fails, the signal will be stored in the memory, even if the ignition is disconnected, troubleshooting, and the fault indicator is off, the fault signal will still be retained in the memory for the maintenance personnel to judge where the car is faulty. After troubleshooting, the fault code will be cleared after 30 seconds of disconnecting the ECU from power.

The fault component is saved in the form of a fault code, which is convenient for the diagnosticator to read out and quickly find out, and the fault warning light is lit to remind the driver that the EFI system is faulty.

Once the sensor fails during the normal driving of the car, the auto fault self-diagnosis system will not only immediately send out the signal of sensor failure, but also the fault self-diagnosis system will also be the same time as the Kaizi car fault Aurora.

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Because the automotive sensor will continue to transmit signals in the process of starting and driving the car, after these signals enter the automobile fault self-diagnosis system, the professional fault detectors in the system will analyze and diagnose the potential fault hazards that may exist in the automobile transportation, and finally through the identification signal, the maintenance personnel will accurately judge the type of automobile sensor failure.

If it is confirmed that the sensor has failed after inspection, the auto fault self-diagnosis system will automatically obtain the fault signal and notify the driver that the sensor has failed.

Once the scarf system fails during the normal driving of the car, the safety and stability of the car will be greatly threatened. Due to the failure of the car microcomputer system is the most common car failure when pro Lacey.

Therefore, in order to effectively improve the efficiency of fault detection of automotive microcomputer systems, researchers have carried out all-round optimization for the design of automotive integrated circuit systems after long-term practical research.

If the microcomputer system of the car dies during the normal driving of the car, the microcomputer controller will automatically adjust to the standby integrated circuit system to ensure that the safe operation of the car is not affected. In this process, the automobile fault self-diagnosis system will record the failure of the microcomputer system in detail, and then adjust it to the standby integrated circuit, which provides accurate data information for the subsequent maintenance of the automotive microcomputer system failure.

Actuator failure is affecting the engine of a car.

A key factor for safe and stable operation. If the actuator fails during the normal driving of the car, the fault insurance will be started at the first time, and the maintenance personnel only need to adopt corresponding treatment measures according to the specific situation of the car's operation and wear in the later fault maintenance process.

When the automotive electronic control unit carries out the self-diagnosis of the automobile fault, it must first send the fault diagnosis signal to the automobile fault self-diagnosis system, and then accept the receipt sent by the actuator.

signal, and finally through the analysis of the signal, the type of car failure is determined.

For example, if the ignition of the car does not fail, the electronic control unit of the car will want the ignition to transmit the ignition signal, and the ignition will receive the fault signal and feed it back to the electronic control power supply to ensure that the ignition of the car can operate normally. On the other hand, if the ignition of the car fails, then the ignition will not feedback the signal even if it receives the signal sent by the electronic control unit, and it can accurately determine whether the ignition has failed.

Internal fault diagnosis imitation virtual disturbance standby circuit can continuously monitor the work of each component of the electronic control system during the operation of the car, when the electronic components are found to be faulty, Nengyu and automatically start the fault running program, the fault is stored in the RAM of the computer in the form of **.

The working principle of the automatic diagnosis system is to detect whether there is a problem in all parts of the car, and then it can be detected in order from the inside to the outside.

The working principle is that through the sensors of the car, the signals are continuously transmitted, and then the professional fault detection personnel record these signals, and the chain can be found to bury the problem of the shed ants.

1. The main reasons why the engine cannot be started are: check whether the distributor, spark plug, high-voltage line, etc. are damp due to the rain or car washing. Check whether the battery voltage is sufficient;

Solution: Turn off the vehicle first, dry the parts of the damp part before starting the car; Temporary power supply is provided by connecting the connecting cable to the battery of another (torture) vehicle in order to start the vehicle.

2. The main reasons for the vehicle to turn off when changing gears are: the engine idle speed is too low; The idle shut-off valve is not tightened and the plug comes off.

Solution: Adjust the gear to the correct idle gear according to the vehicle situation; If the plug on the idle shut-off valve or connection section falls off, simply plug it back in.

3. The steering wheel trembles when the vehicle is moving, and the main reasons are: whether there are mud blocks, stones and other debris sticking to the tires of the vehicle; The tire is deformed by impact or the wheel balance weight falls off; Wheel alignment is not performed after the tire is replaced.

Solution: Remove stones from the gaps of the tires and debris stuck on the wheels. In order to avoid potential safety hazards, the deformed tires should be replaced in time, and the nearest auto repair shop should be found to install the balance weight. You should find a professional auto repair shop in time to carry out four-wheel alignment to avoid potential safety hazards.

1. Four basic principles of automobile fault diagnosis:

1) The principle of simplicity before complexity, easy before difficult.

2) The principle of thinking before acting, ripening before birth.

3) The principle of first up and then down, first outside and then inside.

Fourth), the principle of first use and first priority.

The basic principle is to judge by the abnormal behavior of the car, and it is also judged and diagnosed based on whether the engine and transmission are faulty.

The basic principle of automobile fault diagnosis is to start with simplicity and then complexity, and easy before difficult. Think before you act, mature before you grow. First up and then down, first outside and then inside. Prepare before use, ** preferred.

What did he think? Did you have an accident with the engine or did you have some other problems?

Diagnosing the car's power system, body system, chassis system, signal system, air intake system, etc., Kuchebao can help you complete this job very well, real-time feedback to your mobile phone receiver, you don't need to know the fault ** to know what is wrong with your car.

Generally, there are two, instrument self-diagnosis and air conditioning self-diagnosis. The rest will have to be decoded. Of course, some cars can also be short-circuited diagnostic plugs, use the flashing frequency of the fault lamp to manually read the code, and then check the fault code book, but some codes can not be read manually.