We never positioned our car service on the outskirts of Moscow as the very one where people come to come to the source of last hope, but it so happens that during the repair it turns out that in the previous car service they read Raikin again until night, and then “twisted it, didn’t do it “. And overlooked. It was the same in this case..
The car is not old or just well maintained. Well, if the car arrived for repair as a holiday, clean, washed, then inside, most likely, there will not be any old problems.
As they say, honor and praise to the driver. However, there can be a purely economic calculation: it is better to be serviced in time than to pick out a malfunction from the car, which will appear as a result of unattended maintenance (MOT).
A light was on on the dashboard, of course, there was an error – and the scanner showed that the control unit was unhappy with the operation of the front right sensor of the ABS system. In order to visually and graphically evaluate it, how it works and whether it works, I displayed an oscillogram on the scanner monitor:
From the waveform it becomes clear that the front left speed sensor is still working, but the front right is in doubt (FR wheel speed sensor).
It is clear, then, the car on the lift and watch. They lifted, unscrewed the wheel and saw:
It is striking that such a “pristine freshness of a new tourniquet”, right? Clearly, it means that the speed sensor was replaced. Further, the question is not in the credibility of the previous mechanics who examined and repaired this car – you should always check everything yourself, see with your own eyes; the sensor is removed and visually assessed for damage (everything could be, could, for example, break the sensor during installation or somehow disable it).
In appearance, everything seems to be working, there are no external influences. It should be noted that this speed sensor uses a magnetoresistive effect and is called a “MRE type speed sensor” (conversational). The principle of operation is shown in the picture below. Pay attention to the picture on the right, the ring with the inscription “Magnetic ring”.
We will come back to him. I want to note that in different sources this ring is called differently, for example, in the figure below it has the name Magnetic encoder
After checking the operability of the sensor itself (in more detail below), when I was convinced that the sensor is in good condition, it is time to look for the cause of the malfunction elsewhere. The design allowed a little look inside:
Then it became clear that it was necessary to remove the drive and inspect the wheel bearing. In the next photo this bearing, pay attention to some attritions – it was badly once installed or other reasons?
A minute later, a malfunction appeared before my eyes:
The magnetic layer is destroyed. It was this that caused the malfunction and showed a “torn” waveform. Just in case (maybe it will be useful to someone), I’ll give a photo with the code for the new bearing, which we put in place of the faulty.
I will not go into the reasons and engage in conspiracy theology (why this happened, what contributed, and so on). I’ll dwell better on another, on the previous car service.
I want to say right away that I’m not going to criticize anyone now, the goal is different: a bit to analyze the work of the previous car service and tell me how to solve this problem with a malfunction of the right front speed sensor.
In the photo at the beginning of the article, I gave an example and said that “a new sensor was installed.” Yes, they carried out some checks in another car service, most likely they read the error: “Faulty right front speed sensor” and replaced it. But such a replacement did not solve anything. Why did this happen? Perhaps in a hurry. Maybe “just did not know.” Everything can be here, not for me to be a judge. And how could you avoid the reproachful look of the client (“Oh, you did not manage!”)?
Like Dmitry Yuryevich (mek, a car service near the Kursky station in Moscow for the diagnosis and repair of Mitsubishi cars), I do not hide my achievements. And it was worth the guys from the previous car service to go online to the addresses:
and some others, where the Legion-Avtodata company posts articles autodata.ru/article/, then a problem of this kind would be solved. See:
This is an emulator circuit for testing MRE-type sensors. And two photos above the diagram – how everything was organized in a small box. Delov – pah, many benefits.
After replacing the bearing with a new one, the problem on this car went away: “Done! Who is next in line? ”.
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