A lucky Global Hawk GX7SUV new car with a mileage of about 5000km. When the vehicle starts running again after a trip, the engine fails to start and the burglar fault indicator lights flicker. The car owner contacted the service station and dragged the car back to the service. The technical personnel of the maintenance station, according to the fault phenomenon, are preliminarily judged by the failure of the anti-theft system of the engine, so the decoder reads the fault code, which is shown as B403, which means that the W line is short circuited on the power supply. After checking the related lines, no problem was found and the safety code of the car owners could not be matched, so the control unit of the engine anti-theft system was replaced, but the engine could not be started and the car was stopped for nearly a month in the maintenance station. Because the owner of the car was my colleague's daughter, my colleagues asked me for help. Fault diagnosis: according to the fault phenomenon, I can also identify the engine anti-theft system failure. Although the maintenance station technicians have checked the related lines and replaced the anti-theft system control unit, in order to ensure all the loss, I have redone the following detailed examination: first open the ignition switch, the instrument burglar failure indicator flicker continuously, and read the fault code of the control unit of the engine burglar system with the diagnostic instrument. B403 is shown, and the fault code of the engine system control unit is read again to show the trouble free code. According to the meaning of the fault code "W line to the power supply short", first check the burglar control unit IP24 terminal 8 and the engine ECM75 terminal connection wire harness, see if there is a short circuit with the power cathode, after checking no short circuit and circuit breakdowns; then check No. 8 terminal wire harness and other wire harness of the IP24 is not connected phenomenon; then, It is suspected that the control system of the burglar system is malfunctioning or fails to match the engine ECM. Because the safety code of the original car security control unit is not correct, it can not match with the engine control unit. The technical personnel of the maintenance station have changed the new control unit and set up the safety code, so the failure of the anti-theft control unit is preliminarily eliminated, and the matching work of the anti-theft control unit and the engine control unit is mainly carried out. First connect the diagnostic instrument, insert the key to turn the ignition switch to the "ON" block, click the diagnostic instrument related options to enter the GX7 car anti-theft system, enter the new set of security code, and then select "read the anti-theft unit to ECM", display success; then reprogram the key, first select the "full wipe key", show erasure success, and then the success, and then the successful, and erase success, and again Choose the "learning key" to show the success of the new key learning. Turn the ignition switch to the "OFF" gear and wait for about 5min. Then turn on the ignition switch to the "ON" gear and find that the anti-theft system fault indicator is still blinking. Use the diagnostic instrument to reenter the anti-theft system, read the static data stream, and find that a "theft proof" item shows "not passed", starting the engine or not starting. At this point, it is sure that the burglar control system itself has no problem. It begins to doubt whether the engine system control unit has been damaged, but why is it damaged? The probability of damage to the control unit itself is relatively small, and no type of control unit can be replaced. At this time, I suddenly think of a single line before entering the security code with the diagnostic instrument. "Please contact the manufacturer's technical department before entering the safety code. After the wrong safety code is continuously input 7 times, the engine computer will be locked out." After asking the technical personnel of the maintenance station, before replacing the new anti-theft control unit, the safety code of the owner can not be matched a few times because the safety code provided by the owner is not correct, and then the safety code is asked to the manufacturer's technical department. Although 3 safety codes are provided, it is not correct. It can be determined that the failure of the control unit of the engine system is scrapped due to the repeated input of the safety code by the maintenance technician. Contact with the manufacturer to order the same type of engine system control unit for replacement, and then program matching: connect the diagnostic instrument, insert the key to turn the ignition switch to the "ON" block, click the diagnostic instrument related options to enter the GX7 model anti-theft system, input the correct safety code and deposit 17 vehicle identification code, and then select "Read anti-theft unit to ECM", display success; then choose "read ECM to anti-theft unit", display success; finally reprogramming the key, showing the new key to learn success. Turn the ignition switch to the "OFF" gear and wait for about 5min. Then turn on the ignition switch to the "ON" gear. It is found that the alarm system of the burglar alarm system is no longer flashing. Use the diagnostic instrument to re enter the anti-theft system, read the static data flow, "anti-theft verification" one show "passed", the other options are also normal, so start the engine, can start normally. It was thought that the car's fault had been ruled out. Unexpectedly, 2 days later, the colleague called to say that the car could not start again, and the anti-theft fault indicator lights flickered continuously. So I took the diagnostic instrument to catch up, and after matching, the engine could start smoothly. Check the anti-theft system circuit and controller interface again. No problems were found. At this time the car has the instructions on the use of the car, so find the introduction of the anti-theft system, found that the use of the remote control of the use of the operation method is: fast press the remote control lock key, driver side locking device unlocked; fast press the remote lock key, the number of effective times up to two times, 4 door latch lock; unlock; Time presses the remote controller to unlock the key, and the 4 door locking device is unlocked. So it is thought that if the remote control is not correct, it will lead to the theft prevention system. After asking the car owner, in the normal use of the car, they all drive to work by themselves. Before driving, the driver's side door is opened by the remote control lock key. After parking, the door is closed according to the lock key. There is no time to notice the length of the key, and there is no trouble. The two time the malfunction occurred was when many people pressed the unlocking key while driving, but the other door did not open, but the driver opened the door from the car to let others into the car. When the vehicle starts to stop once, the anti-theft system will think that someone enters the car illegally, locks the engine, can not start, and can work properly after rematching. By understanding this situation, the reason that the engine can not start the fault is that the driver does not use the remote control to open the door, which causes the anti-theft system to play a role and can not start. Immediately told the driver to use the remote control method correctly, and then no such fault occurred. Fault summary: the vehicle fault repair process can be said to be twists and turns, and takes up to a month. It is a relatively simple use problem. If the owner carefully read the manual after buying a car, there will be no similar wrong operation. In the process of maintenance, the technical personnel of the maintenance station can not handle calmly when they meet the problem of anti-theft. They only want to enter the correct safety code, but ignore the consequences of the safety code of the input error. The result results in the lock of the control unit of the engine system. The dual control technology of the car door guard system is designed to prevent the repeated opening and closing of the other door locks when the driver uses the car, and it may also have the safety of the vehicle, preventing the outsider from locking the driver while taking the opportunity to enter the car. But if this humanized design fails to make good use of it, it will cause some unnecessary trouble. Therefore, in the rapid development of new automobile technology, every one of us, especially the technical personnel of automobile maintenance, should learn to grasp the advanced technology of automobile and keep up with the development of automobile technology. Only by correctly understanding the car and using the car reasonably can we provide the car with better service for us.