A BMW in 2002 740, due to change the gearbox after the wave there is a problem, driving for some time after the automatic transmission can not jump from the 4 block to 5 block phenomenon. Previously, it was checked several times in other repair shops and no problems were found.
    I tested the car with GT1, but the test results show that everything is normal. Taking into account the possibility of the problem is not in the circuit, and automatic transmission inside and no movement, the valve body can not be damaged, it is speculated that the quality of automatic transmission oil. But the maintenance workers said, re-change the transmission oil, the fault remains the same. Is the oil more, but the BMW automatic transmission of the oil hole in the above, if the oil will automatically overflow overflow. In this way, the author is also confused, had to try to use GT1 into the expert mode for testing, automatic transmission internal shift solenoid valve to do the test did not find the problem. And then with the GT1 oil level inspection, but the screen shows the oil temperature is too high. The conditions for performing the oil level inspection are: idling state, headlight, and oil temperature below 50 ° C. So the car will be cooled, when the temperature is completely down after I continue to detect the door, but start the engine, the oil temperature immediately rose to 60 ℃, more than the detection conditions, it can not detect the oil level. After a period of time, read the actual value of the oil temperature sensor is 130 ℃, which is far more than the oil temperature range. The problem is likely to be automatic transmission computer to monitor the oil temperature is too high, so that the gearbox into the protected state, do not let it into the ultra-speed gear.
    Automatic transmission oil temperature is high, indicating that the automatic transmission of the radiator and tubing is blocked, need cleaning. But the repair master told the author that they have carefully cleaned the automatic transmission pipeline, did not solve the problem. Hand touch automatic transmission radiator, the temperature is high, indicating that the automatic transmission radiator may be a problem, need to be replaced. In addition, the author also found that the car is also relatively high water temperature, tightly unscrew the water tank cover and found that the water tank was white, is the cylinder bed washed? But the engine work properly, there is no water within the oil, the water tank is also normal water level. So the coolant inside the tank all let go and found that coolant like lime water, very abnormal. This cooling water is likely to block the radiator, and the automatic transmission of the radiator is cooled by two pipes, if the coolant does not cycle or block, cooling effect is naturally poor. Remove the automatic transmission radiator, ready to clean the automatic transmission of the radiator. When a cooling water pipe of the automatic transmission radiator is removed, it is found that the inlet port of the automatic transmission radiator is almost blocked by the white precipitate, and there is not enough coolant to enter the radiator of the automatic transmission for the cooling cycle. Remove the sediment, rinse the radiator, water tank and waterway after the test, automatic transmission jump block normal, driving performance quite good. But I still do not understand how coolant will become white? At this time happens to be a new BMW 530 to replace the thermostat, the car's old thermostat is also a white, like gypsum. Asked the mechanic and the owner after the speculation may be used in this plant cooling water quality problems, adding a tank after a period of time will be bad, white powder.
    Special · home · comment
    Although the case is the failure of the BMW automatic transmission, the causes of the failure and the characteristics of the failure and the current issue of "golf automatic transmission uplift difficulties" is exactly the same. Symptom is also caused by the increase in vehicle temperature, and the performance is also in the automatic transmission of the upshift performance, the final failure of the source are automatic transmission oil heat dissipation, the two cars have been in other repair shop for maintenance. The only difference is that only one is "high-level BMW", one is "ordinary Gol".
    But the reader if the two articles together to read, you may find "golf automatic transmission uplift difficulties," a text is very clear, relatively strong detection, fault resolution in common sense, so I commented "golf Automatic transmission upstart difficult "article, in the end or put forward the test should be improved and improved place. Looking back, I look at this article, my heart is indeed a kind of unspeakable taste. We look at: pick the car, the instrument did not read the fault detection, so began to infer "is likely to ... ... speculation is ... ... Is it ... ... so that the author is a confused, had to try ... ..." And so on, so that the root cause of the fault is purely a "chance" phenomenon - in the use of GT1 oil level inspection found that the screen shows the "oil temperature is too high", if not this "accidental", the car's fault solution possible Really want to pay some twists and turns. On the automatic transmission oil temperature is too high (cold normal, hot car failure) problem, I "golf automatic transmission upstart difficult" case of the comments made a brief description. For such a problem, "temperature" is a fault detection in the absence of a "main line", all around why the temperature is high, what causes the temperature is high, the temperature will be high, the temperature in the automatic transmission oil circulation chain The change is normal and a series of problems to carry out fault detection work. Like "golf automatic transmission upstart difficult", the full use of infrared thermometer for temperature detection, which is very smooth to find the root causes of failure, effortlessly ruled out the failure. If the case also uses infrared thermometer for temperature detection, it may be found that the failure should also be a very easy thing.
    But the key is the existence of the following two aspects:
    First, the maintenance personnel in the fault detection before the failure of a detailed analysis, did not figure out the cause and effect of the failure occurred, so when the fault detection is unfounded, no purpose, only "very likely ..., presumably ... ... is it ... ..., had to try to use ... ... "approach to investigation. It can be seen, fault detection before the fault analysis to determine is very critical. Published in February 2006, "Peking University International MBA (BiMBA) NEWSLETTER" in Mr. Ma Hao's article entitled "donkey donkey: the definition of" the problem "of the article, the article mainly describes the management decision-making" The definition of the problem, "the article pointed out:" The definition of the problem is the starting point for decision-making for the decision-makers to create a certain momentum and atmosphere, to provide the premise and basis for action ";" on the same issue, different people are likely to have Different views and understandings, given the same time or phenomenon, due to experience, experience, awareness and interests and other factors, people may see a different problem, or have different definitions of the problem. "; In the organization, a question once given the official, formal definition of the authority of the organization, the definition of the problem, to a large extent, is to determine the problem, and the corresponding decision of the collection of information, action The definition of the problem throughout the decision-making process. "In fact, we in the vehicle fault diagnosis," fault car failure "Is the so-called" problem "," vehicle maintenance technician "is the so-called" decision-makers "," analysis of the fault to judge "is the so-called" problem definition "," maintenance personnel to take the detection methods, "Is the so-called" decision-making ". It can be seen that if we do not analyze the problems of the vehicle according to the characterization of the fault, the "problem" of the failure of the vehicle, we can not give the "definition" of the "problem" as a "decision maker" vehicle maintenance technician It can not be "decision". That is, in the process of troubleshooting, maintenance personnel to take the detection method, detection methods and testing process on the "no sense can not", East a hammer West a stick, so that the whole process of solving the problem is a failure. We must be clear that the existence of "problem" is objective, leading to the existence of the "problem" is also objective, fault phenomena and fault reasons are inseparable between the inevitable link, the process of troubleshooting is to find its inevitable law The definition of "problem" and the "decision" process, which requires maintenance personnel to continuously improve and strengthen their own analysis of "problem" and "problem definition" ability. The "definition" of the "problem" is right, and the "decision maker" of the "decision maker" is right, and the strategy to solve the problem is right, and the "problem solving" becomes the "inevitable result".
    Second, the means of failure detection process a single, the use of testing equipment is not sufficient. Fault detector in the minds of the majority of maintenance personnel has become a "unique", as long as the electric control vehicle failure, we first thought is to use fault detector for fault code read, read out the fault code - "happy" , Did not read the fault code - "disappointed, helpless". Often see a lot of maintenance personnel so that "test results show that everything is normal, had no doubt ... ...". Of course, here we are talking about the problem - there is no detailed breakdown of the relationship, but we can only use the fault detector on the vehicle fault code or data flow detection? Now the car detection and diagnostic equipment manufacturers introduced a large number of useful detection equipment and testing tools, such as infrared thermometer, etc., on the fast and accurate diagnosis of fault parts is very helpful. In this recommended the majority of maintenance technicians, to pay close attention to the development of diagnostic and diagnostic equipment, and actively apply the new testing equipment to the maintenance practice, as soon as possible from the "experience car repair" and "feel car repair" to " Car "and" data car repair ". On the detection of diagnostic equipment, perhaps the maintenance staff do not know, perhaps the repair shop did not, perhaps the maintenance staff did not realize that perhaps the maintenance staff will not use, but in any case, as long as you realize this, I believe skilled application Just a matter of time.