Here is this snow-white handsome:
Its owner (let’s call him Ruslan) brought his handsome man to our Hybrid service straight from the Lexus Center of Yekaterinburg. The officials, having replaced the inverter power module during the service campaign, could not start the car, having diagnosed that it was necessary to replace the motor generators and the high-voltage battery (though they didn’t take the money for such “repair and diagnostics”).
And the background of getting this car to the official is:
In June 2017, when driving along the highway at high speed on a hot day, Ruslan’s car suddenly died out. I think that many advanced owners of hybrids who read our forum would immediately be able to determine the cause of the failure without a scanner – the power module in the inverter burned out.
But Ruslan, unfortunately, turned out to be not such a technically competent owner, and having loaded his car on a tow truck, he brought it to his friend – the director of the largest car service in the city (you will understand at the end of the story why we do not call the city and car service).
The director called “the most competent diagnostician in the city,” who diagnosed directly with Ruslan – the transmission jammed. At the same time, the “diagnostician” did not even bother to connect a scanner to the car, but carried out diagnostics “by eye” and “by ear”: if when you try to start the car in the box there is a muffled blow and the car does not start, then the motor-generator burned out!
The car was sent from a diagnostic site to a locksmith, where “the best box specialist in the city” took up its repair. When the “specialist” removed and dismantled the box “to the bolt”, I realized that everything was in the best condition in the box and there weren’t any malfunctions.
Then Ruslan was invited to carry out a major overhaul of the ICE! The owner of the service (Ruslan’s friend) convinced him that with a run of 150 t.km. its internal combustion engine necessarily needs major repairs: replacing rings, liners, etc. And since the ICE has already been removed, then there is no need to pay for the removal / installation of the ICE during the repair, and Ruslan will be able to save a lot on this. Once a friend advises, then you have to do it … Not quite understanding why, but Ruslan agrees to overhaul the ICE …
A month later, the internal combustion engine was “repaired”, but the car did not start, and it did not start … When you try to start in the box, you hear a thump and that’s all …
Then heavy artillery came into play – they finally connected a scanner, which produced a “whole bunch” of errors on the inverter. After reading the Internet, artisans realized that the problem was in a burned-out power module. There on the Internet, they found my phone and advised Ruslana to buy a power module from us.
That very day I received the first call from Ruslan. Hearing the price of the power module, Ruslan said that on sale on Avito there are modules 40% cheaper than ours. I warned him that a lot of faulty modules are being sold under the guise of serviceable ones on the Internet, and advised me to buy only from trusted sellers, and also told him that he can replace the power module in his car completely free of charge with service company officials.
After that, Ruslan disappeared for a month and a half. As it turned out later, he bought power modules on the Internet and put them on his car. But it did not bring any results – the car did not start …
Then in November 2017, Ruslan brought his car to the official Lexus Center-Yekaterinburg. To repair it for free.
There, he replaced the power module in the service campaign, but when it tried to start, it burned out – the motor-generator twitched for a second, there was a familiar knock, and … They refused to change the service for free, since the service campaign was carried out according to all the rules prescribed in the dealership documentation. Having reached the verdict that the inverter was burned out due to a short circuit in the motor generator, he was offered to install a new motor generator, and at the same time a high-voltage battery, since the VVB on the car was supposedly in very poor condition … The price for such repairs was much higher than the cost of the car itself.
So this Highlander was in our service. Accepted for repair.
Diagnostics showed that in all vehicle systems there are more than 50 different errors.
We begin to separate the flies from the cutlets and it turns out that the main errors are the inverter and the ABS system. All other errors are consequences..
We begin to deal with the inverter. We remove the power module and, to our great surprise, it turns out to be fully operational: there are no broken power transistors, no breaks, no short circuits in it! In order to accurately verify its performance, put it on our Lexus. The result of our diagnosis is confirmed – the whole power module!
So two more mistakes down. By and large, only one remains – P0A60 with 294 and 501 subcodes. It indicates that there is an overload of phase V in the inverter. Moreover, the overload is on the first motor generator.
It is clear that overload can only be provided by a starter motor-generator connected to the inverter. Getting started with him. We carry out all the verification procedures that are described in the repair manual.
To our great surprise, there is no short circuit in the motor generator! All windings ring well and do not pass between each other or on the case. Wonders! But automotive diagnostics is an exact science and there are no miracles in it …
We begin to carry out verification procedures that we have developed independently, during a large number of repairs of these boxes.
And then the first surprise awaits us. When we start supplying voltage to the motor-generator windings from the inverter in the “manual mode”, we see that the resolver shows that the rotor is in the U phase position. Accordingly, in order for the motor-generator rotor to turn forward, we must apply voltage to the next phase – V. We do this – open the second transistor to supply voltage to the winding V. The voltage is supplied to the winding and the rotor of MG1 is shifted … (windings: U, V, W.) But it is shifting (spinning) not forward and back! We are in shock! This we have not seen! Why does the rotor rotate the other way ?! We apply voltage to phase W. And here the rotor, instead of spinning in one of the sides, simply remains in place, and the current strength on its winding surpasses 150 Amperes!
So the cause of the malfunction by the hybrid system control unit is determined correctly – there is a big overload when the rotor is in the phase V position.
Why? The brain begins to slowly melt … All components of the system are working, and the system does not work – the rotor does not rotate from the position of phase V either forward or backward!
One assumption remains – the resolver of the motor-generator, which shows the actual position of the rotor, has failed. We carry out a complete diagnosis of the resolver. Result: fully functional and shows the position of the rotor is ABSOLUTELY correct. All! Dead end! Not even the slightest assumptions anymore. We decide to remove the gearbox.
It is worth adding to this that while we were looking for a problem with phase V overload, we were simultaneously looking for the problem of a bunch of errors in the ABS system. And the results of the ABS system diagnostics were disappointing: a signal to the ABS control unit from actuators did not arrive on several wires. And the wiring of the ABS to Highlander is located in such a way that you can’t get to some of the wiring harnesses along which the signals go to the ABS unit …
We begin the process of removing the box from the car. The box on this car is removed assembled with the engine. Having removed the box from the car, we conduct its external examination. It is immediately evident that the wire harnesses connecting the motor-generators (father-mother) differ among themselves in that on MG1 the “mother” is clean and the “father” is dirty.
But on MG2 the opposite is true: the counterpart of the box is all dirty, and the wire connector is clean!
A thought creeps in: are the power wires not mixed up when disassembling the boxes with the “best box specialist”!
The answer is given even without measuring the length of the wires (and they differ in length by 5 cm) the mounting connector that hangs on the MG2 wire, although it should be fastened to the MG1 case
We examine the connectors themselves carefully and see that they are really confused: in the photo, the native location of the mounting bolt is circled in red, and the location after the “non-native” connector was screwed in blue.
Those. to a specialist who disassembled-assembled the box, it doesn’t matter which wire to which place to put during assembly – the connectors are the same … But the wires are different! On MG2, the connector that connects to the inverter is rotated 180 degrees relative to almost the same connector that connects to MG1! And it turns out that the super-specialist connected the phase U of the inverter of the control MG1 with the phase W of the box, i.e. motor generator. Therefore, the motor generator makes an attempt to spin, when the resolver has tracked that the rotor is in position U or W. But it spins in the opposite direction and only to the position of phase V. Further, the control unit cannot understand which transistor to open, because the resolver tracked that the rotor is spinning in the other direction … And the inverter is overloaded in phase V. At this time, the notorious “blow” is heard from the box.
To put the wires in place, you can not do without removing the box from the car. But the engine would still have to be removed to fix the ABS system! It is good that we traced this problem even before the ICE was removed. And here it is the reason for the non-working ABS system:
And here is how it should look on a working car, where everything is assembled correctly:
At the request of the owner, we inspect the “uncapitalized” ICE. We conduct a pneumatic test of the internal combustion engine, and we see that in the first cylinder there is a hole in the exhaust manifold – air freely leaves the manifold under pressure … We scroll the crankshaft several times, but the result is the same – the internal combustion engine is faulty. Here you have the capital …
We remove the engine valve cover and see that the exhaust valve cup is recessed down, although the cam does not press on it, i.e. exhaust valve in the first cylinder is constantly open.
Why? As many have already guessed, the valve stem is bent. How? This can only be told by the minder who “uncapitalized” this engine.
The oil emulsion is circled in green in the photo, which was in a large number in the newly repaired ICE. Where did she come from?
We look at the oil in the engine crankcase: there is also an emulsion.
We get the answer as soon as we start disassembling the ICE – the intake manifold is simply not bolted to the ICE! A few bolts are simply baited and even loose, and not even loose. And the collector design here is such that the antifreeze in this case freely enters the oil.
What would happen after the ICE started working, I don’t think anyone needs to explain – he would have struck this emulsion most likely on the first day of work. We won’t talk about a bunch of missing bolts at all …
Ruslan takes the whole repair process on photos and videos. The footage is immediately sent to a friend on Watsap. After half an hour, the “friend” calls back: “Repair, I will pay for everything. The jambs are really mine.”
Everything is good when everything ends well. Ruslan’s friend really paid the full cost of the repair. And Ruslan, who had to “stay” with us for a couple of days, left home satisfied. At the request of Ruslan, we don’t “light up” his friend’s service.
Conclusion: it is not always worth repairing a car even from your friend, whom you trust 100%, but who does not have sufficient qualifications. Complex repair is better to entrust to a specialized service.
Good luck on the road!
Gordeev Sergey Nikolaevich
© Legion Avtodata
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