Device automatic box transmissions and its malfunctions is a complex topic and worthy not of a separate publication, but of a whole series of articles. Therefore, we will start with the simplest and most common and gradually move on.

Simplified, the automatic transmission consists of five main parts:

1. Hydraulic torque transformer. Replaces the usual clutch on the "automatic" and transmits the moment from the engine to the box using oil circulation.

2. The box itself is a set of planetary gearboxes with different gear ratios... Conventionally - a set of different gears.

3. Gear shifting mechanism. Usually consists of a clutch pack, freewheel and brake band, which are moved by hydraulic tappets. This system changes gears, closing certain gears in planetary gearboxes.

4. Oil distribution block (valve body). Here are the solenoid valves, which, when closing and opening, supply oil to the hydraulic pushers, and these, in turn, set the gear selection mechanism in motion. Valves are also called solenoids, although strictly speaking solenoids only open and close valves. The valves themselves are correctly called spools. The oil for the distributor is supplied by the pump from the oil receiver.

5. Transmission control unit. Relatively speaking, the "main computer". It drives all hydraulics based on sensor readings.

What the control unit takes into account in the first place:

The gearbox input shaft speed is the engine speed;
- the speed of rotation of the output shaft of the box is already the speed of the car itself;
- the temperature of the oil inside the box - is there any overheating;
- how deep the accelerator pedal is - what acceleration the driver expects;
- the position of the automatic transmission selector lever - which mode is on ("drive", "parking", "sport", "neutral" or "reverse")

Typical story

The car "does not drive well", and on the dashboard the alarm lamp for the emergency mode of the gearbox lights up. Crash! Anxiety! There is no need to panic and wonder at what percentage to take consumer credit for 100,000 rubles. In most cases, complex hydraulics and gears are in perfect order. The main source of problems is "buggy" electronics. Something somewhere is not working correctly and the control unit intelligently turns on emergency mode, so as not to mess with the box of troubles. Today we will figure out what can fail in the electronic part of the automatic transmission and how much the repair costs in this case.

By the way, what is emergency mode?

It is impossible to understand this without a detailed understanding of the device of the "automatic machine2" box, so we will not bore you with details. get to the car service on its own, and there the debriefing will begin.

So what broke?

1. Breakage of air flow sensors, position throttle, camshaft or ABS sensors

How does it manifest?
The automatic transmission enters emergency mode during switching and acceleration-deceleration, then suddenly exits the emergency mode.

How to check?
Such a malfunction can be easily identified by simple computer diagnostics. Price computer diagnostics usually ranges from 1,000 to 3,000 rubles.

How is it repaired?
Replacement. It is best to fix such a breakdown by replacing the sensor. The cost of a new sensor rarely exceeds the five thousandth limit, although an air flow sensor can cost up to 20 thousand on individual vehicles. Replacement takes 1-2 normal hours on average. The cost of a standard hour on all services is different, but usually ranges from 800 to 1,500 rubles. When it comes to specialized services for expensive cars, then the amount can be increased arbitrarily.

2. Failure of the automatic transmission control unit itself

How does it manifest?
The automatic transmission "tightly" goes into emergency mode and does not come out of it.

How to check?
Computer diagnostics does not always help; to accurately identify the problem, a trial replacement of the engine control unit may be required. If computer diagnostics It was not possible to do without, then for a trial replacement can be carried out for about 1,000 rubles, plus a deposit for the installed control unit.

How is it repaired?
Replacement / repair. Replacing the control unit with a new one will immediately bring the automatic transmission to life. The cost of the block itself is different cars varies from 5 to 40 thousand rubles, and the cost of installation is rarely more expensive than one standard hour. You can also try to repair the engine control unit. For unit repair and restoration of factory software in service centers may ask for up to 10 thousand, but the problem cannot always be fixed by repair.

3. Malfunction of electrical wiring or contacts (oxidation, short circuits, breaks, insulation damage, etc.)

How does it manifest?
The automatic transmission enters emergency mode and exits it for no apparent reason (lives its own life) and at one point remains in "suspended animation" forever.

How to check?
Failure of wiring or contacts can cause errors in devices that are actually serviceable. It is necessary to diagnose such a breakdown mechanically, by removing wires and contacts, by inspection or "ringing".

Whatever you say, an unpleasant problem. The cost of identifying it can go up to 10,000 rubles, if it is necessary to extract all the wiring. This is due to the fact that the electric scythe is retracted into hard-to-reach places and for its complete inspection it is necessary to disassemble and remove a large number of elements.

How is it repaired?
Repair or replacement. After identifying the exact location of the short circuit, breakage, oxidation, etc. usually all that remains is to eliminate the damaged area or contact, which can cost 1,000 rubles. If the entire electric braid has already been removed from the car, and during diagnostics it turned out that it needs to be changed completely, then a set of wires can cost up to 30,000 rubles.

4. Failure of electronic pressure regulators and automatic transmission solenoids

How does it manifest?
Gears do not switch at certain speeds, when switching, shocks are felt, strong slippage, the transition to emergency mode occurs at certain changes.

How to check?
It is often determined by computer diagnostics, and is most accurately checked by measuring electrical parameters (resistance, inductance). The solenoid is a simple inductor and it is not difficult to check the parameters of this coil. Solenoids, as we already know, are usually located in the valve body of the gearbox, and for measurements electrical characteristics it may be necessary to remove the block, which is associated with a partial disassembly of the automatic transmission. Such diagnostics can cost up to 5,000 rubles.

How is it repaired?
Replacement. The correction of such a breakdown is the replacement of pressure regulators or solenoids. Usually, the entire block changes, the cost of which can vary from 10 to 30 thousand rubles. Repairing a block or individual solenoids is rarely advisable, as the cost of repairs is usually comparable to the cost of a new block.

5. Malfunction of the sensors of rotation of the input and output shafts of the automatic transmission

How does it manifest?
The automatic transmission goes into emergency mode when the selector is moved to position D or at the first switch.

How to check?
Easily detected by computer diagnostics.

How is it repaired?
Replacement. The rotation sensor (speed sensor) is easy to replace and inexpensive. The replacement procedure with a new sensor is unlikely to cost more than 5,000 rubles, even on new cars.

6. Malfunction of the gear selector position sensor

How does it manifest?
On the gear indicator on dashboard mode icons (P R N D) that do not correspond to the actual selector position are displayed. Or there is no indication at all, the automatic transmission transition icon to emergency mode lights up, but the box is working correctly.

How to check?
Such a malfunction is not always detected in the diagnostics, since the sensor may not be connected to the "brains" of the car. A breakdown of the selector position sensor is detected unmistakably by the above signs.

How is it repaired?
Replacement / repair. approximate cost of this sensor - up to 5,000 rubles, replacement is rarely more expensive than one standard hour. If the sensor is collapsible, then perhaps it can be repaired. First of all, it is worth seeing if the contacts have oxidized, since most often the sensor fails when water gets into it. In this case, cleaning up contacts can save you unnecessary expenses.

7. Malfunction of the automatic transmission oil temperature sensor

How does it manifest?
The automatic transmission goes into emergency mode either immediately or after heating the oil to operating temperature.

How to check?
Usually detected during computer diagnostics, however, sometimes it is worthwhile to carry out a trial replacement of the sensor.

How is it repaired?
Temperature sensors cannot be repaired, so such a breakdown can only be corrected by replacing. The cost of the sensor usually ranges from 1 to 5 thousand rubles.

What's the bottom line?

As you can see, automatic transmission repair is not always so scary. Do not trust dealers or craftsmen at the service station if they refuse to understand the breakdowns of your box and say that only it will help here complete replacement unit. Contact specialized services that deal with "automatic machines" and where it is more likely to get an authoritative opinion about the breakdown of the box.

As a rule, serious breakdowns rarely occur unexpectedly and without symptoms. In other words, in the overwhelming majority of cases, noise occurs in the automatic transmission when driving, the box can be switched by jerks and jerks, automatic gearbox slippage occurs, etc.

At the same time, especially before buying a used car, it is important to know how to understand that the automatic transmission is dying, as indicated by the reasons for its appearance. Next, we will look at how to check the automatic transmission, as well as what signs and symptoms to look for.

Read in this article

Automatic transmission malfunctions: symptoms and signs

To begin with, checking the automatic transmission by analogy with the manual transmission will not be entirely correct. Often, the absence of noise, grinding, knocking, squeaking and vibrations of the manual transmission, as well as smoothness and clarity when changing gears, speaks of the serviceability of the and itself.

If we talk about a hydromechanical automatic transmission, in this case, the box needs a more detailed check. First of all, even if the unit is currently working more or less normally, this does not mean that after a few hundred kilometers the box will not fail.

On most cars, a sure sign of a problem with the machine is when the "AT" lettering on the dashboard comes on. This is a kind of "check" box machine (). At the same time, unscrupulous sellers often discard errors before selling a car, and in some cases physically muffle the indicator.

First of all, on an automatic transmission, checks need to start with oil, which is a working fluid and can tell a lot about the owner of the car, the maintenance and condition of the box.

Pay special attention to (checked on a flat surface, after warming up the box, the gear selector is set to "N", on some automatic transmission models to "P"). The ATF level "hot" must be between "HOT" and "COLD".

To check the condition of the oil, in most cases, it is enough to remove the automatic transmission oil dipstick, and then evaluate the color of the oil in the automatic transmission box, the smell of ATF, the degree of fluidity, etc. Normally, the oil should be transparent and as pure as possible, it should not have a burnt odor.

If this is the case, then the transparency of the oil indicates that the owner not so long ago serviced the box, the fluid is fresh and there is a high probability that the clutches in the box itself do not slip, the oil in the automatic transmission does not overheat, etc. By the way, darkening of the liquid is allowed with mileage, however, it should not be cloudy, thick and with obvious admixtures of ATF.

Changes in properties and contamination can be easily identified with a sheet of blank paper. Just drop a few drops on the sheet. The oil stain should be free of steel shavings, obvious impurities, etc.

In cases where the oil is cloudy, inclusions of metal shavings are visible, and there is also a burning smell, then this clearly indicates wear, serious problems with the automatic transmission and the fact that the owner did not repair, and also does not pay due attention to the issue of servicing the unit. The presence of a tow bar can confirm the guess, as this indicates a difficult operating conditions of the car.

The next step is on the move. First of all, you need to make sure that there are no extraneous noises, knocks, strong vibration... Before starting a trip, you need to check the quality of the box "cold" and "hot", standing still and holding the brake pedal pressed.

Of course, all modes should be enabled correctly and quickly. Switching delays are not allowed. Also, if the automatic transmission is cold, when switching from "P" to "D" or "R" mode, you may feel a slight and imperceptible jolt, as well as slight vibration. Now, this is the norm. If a clear blow is noticed, this may indicate various breakdowns (for example, gearbox pillows are faulty, an automatic machine dies, etc.).

Then you can start moving. While the gearbox is cold, during the first kilometers the moment of gear changes "up" and "down" can be felt more clearly in the form of a slight push. Then, after the unit warms up (for this you need to drive about 10-15 km by car), the indicated switching moment is normally almost invisible.

Also, after warming up the automatic transmission, the car must be stopped again. Normally, "hot" shocks when switching to different modes should almost completely disappear. If no comments have arisen, you can continue the checks on the move by activating all automatic transmission modes.

First you need to put the car on a flat section of the road, turn on the "drive" mode, or reverse(reverse R), then release the brake pedal without pressing the accelerator pedal. The vehicle should begin to move smoothly forward or backward. Then the car must be put on the rise, in the "drive" mode, release the brake and do not add gas. The car, with its nose on the rise, should not roll back.

Next, acceleration from standstill is checked, both smooth and active. With a smooth acceleration, the car should normally respond to the gas pedal, accelerate actively, without failures, jerks, delays. Gears must switch clearly and in a timely manner (can be determined by the tachometer).

With active acceleration "pedal to the floor", the box should allow the engine to spin up to high revs, that is, in the first and second gears, the revs can reach the red zone. Also, when switching from 1st to 2nd in this mode, a clear jolt can be noticeable, which is the norm for many automatic transmissions, especially with mileage.

If, after active acceleration, you release the gas pedal, as the vehicle decelerates, the gears should shift “down” imperceptibly up to the first speed. With sharp braking, the machine must gently and quickly drop all gears to first speed, and without jerking, hitting or delaying.

In the event that the machine has passed the specified checks, it is also necessary to exclude the possibility. This malfunction is not always noticeable at first glance, but it may indicate a serious problem with the machine.

So, getting used to the behavior of a particular car, you need to pay attention to the tachometer again. Automatic transmission slippage is actually that, but does not engage. The same can be said for the gears in the box. It turns out that the driver is stepping on the gas, the engine speed increases, but the car does not accelerate properly.

Slipping can be seen by the "jumping" tachometer needle, when the engine spins too easily, the speed rises, but there is no timely gear change (the automatic transmission is slipping).

At first, the problem is not very noticeable, but when the malfunction progresses, the delays are too long, the gears begin to switch with bumps, the automatic transmission kicks and jerks when switching.

What is the bottom line

As you can see, when choosing a used car with an automatic transmission, it is important that the automatic transmission works flawlessly. Normally, the automatic transmission works smoothly and smoothly, without slipping. The thrust from the engine should be transferred to the wheels in a predictable manner, without obvious losses, the car should not over-consume fuel much (provided there are no other problems with the engine, power system, etc.).

Although small shocks are allowed on a cold box, after warming up, a serviceable automatic transmission should work as smoothly as possible with a quiet ride. Sharp accelerations can be accompanied by a more tangible pushing the car forward, especially when changing from first to second gear, but there should be no knocks or jerks.

Finally, we note that even if at first glance the operation of the box does not cause suspicion and remarks, it is optimal to visit a service station before buying a car for professional diagnostics of the automatic transmission and the entire car. This approach allows for a relatively low cost to detect hidden defects and breakdowns of the machine, engine and other components and assemblies, subject to their presence.

Automatic transmission repair scheme

Wherever you decide to repair the gearbox, the whole process goes according to the following scheme:

diagnostics,
dismantling the box,
disassembly of the box,
complete set with spare parts,
assembly (installation),
installation on a car,
diagnostics after repair.

To fix the problem yourself, you will need some car mechanic skills, tools, time to work, patience, and perseverance.

All automatic transmissions are arranged the same, but there are two types of transmission control - hydraulic and electronic. Their renovation has some differences.

Breakage signs

It is important to notice transmission problems at the earliest possible stage. Then, when, you can avoid complex repairs. Quiet and smooth operation of the automatic transmission is considered normal. There are a lot of signs that something is wrong with the box. Most often it is extraneous sounds when shifting gears or during robotic transmission. It can be crunching, clicks. Bad smell also speaks of problems. It can appear during long-term or short-term operation of the box. It is worse if the gear shifting slows down, or one of them does not work at all. Then immediate intervention is required.

Do not be lazy to look under the car, it should be clean there. Red spots will indicate an oil leak from the transmission. Checking the oil level regularly is a must. Normally, it should be translucent, reddish in color. No burning smells or muddy shades! If they appear, it's time.

The main causes of breakdowns

Automatic transmission malfunctions often arise due to not correct operation... The transmission becomes unusable due to insufficient oil level or overheating. For this reason, the gears wear out, the machine can jerk when changing gears. As a result, any part of the automatic transmission may fail. Shocks while driving indicate overheating of the oil and the appearance of problems in the valve body.

Aggressive driving with hard acceleration and braking will erase details. Does not add durability to the box and driving in traffic jams, slipping. All this leads to overheating of the box and has a bad effect on its general condition.

All faults are divided into two subgroups. They can occur in

electronic control system,
mechanical and hydraulic parts of the gearbox.

If a malfunction occurs, the automatic transmission goes into emergency mode, that is, it goes to third speed and does not switch. The corresponding icon appears on the display.

If problems have arisen with the electronics, then it will not be possible to fix them by repairing the automatic transmission. Therefore, it is important to understand the nature of the faults.

Troubleshooting methods

In diagnostics, the main thing is to collect the necessary information and interpret it correctly. Therefore, it is better to consult a specialist. Determine what the problem is at the service station, and take care of the repair yourself. Without proper experience and equipment, you will spend a lot of time on diagnostics. There is a mechanical and.

General scheme carrying out diagnostic procedures:

check the oil,
check the operation of the engine at idle speed, the connection points of the wiring and cables,
determine the error codes of the operation of the control units (CU) of the gearbox and engine,
check the box on a car without movement,
check the automatic transmission in motion,
check the pressure inside the control system.

Electronic control system and diagnostics of its malfunctions

If the cause of the malfunctions is electronics problems, then most likely you will not need to dismantle and disassemble the automatic transmission. Diagnostics of malfunctions in this system is carried out by the control unit. It monitors the sensor signals, the transmission ratio and the resistance of the output circuits. Malfunctions of such parts and assemblies may occur:

input sensors,
electronic control unit,
executive devices of the control system,
violation of the integrity of the electrical wiring connections.

The transmission computer receives signals from various sensors. If some parameters are out of order, it writes the code of this problem (DTC) into memory. You can decrypt such numbers using a special scanner.

Diagnosis of mechanical and hydraulic problems

These are the main problems of the automatic transmission itself. They are conventionally divided into three subgroups:

Damage to friction groups, bushings and housings, calipers, planetary gear sets, pump and other mechanics.
Defective transformer. This includes:
- breaks in the splines of the wires,
- mechanical destruction of the blades,
- overrunning clutch,
- wear of the main blocking clutch,
- depressurization of the piston oil seal.
Problems with the mechanics of the hydraulic plate.

Dismantling the automatic transmission

If the diagnostics were successful and you cannot do without dismantling, then we proceed to this stage of the automatic transmission repair.

You will need a special lift, or at least a viewing hole. As well as a transmission jack and a set of keys. It is better to perform this procedure in a specially equipped garage or box. It will not be superfluous to invite several physically strong guys to help you move the removed box. Its weight is beyond the strength of even a very strong person. Further action plan:

disconnect all communication tubes and cables;
unscrew the torque converter mounting bolts, as well as the motor flywheel membranes;
remove and move the gearbox;
assess the scale of the breakdown and start repairing.

Before removing the gearbox, the oil does not need to be drained from it. However, then do not forget to substitute the container in the place where the oil supply pipes are attached when you disconnect them - otherwise you will get an ugly puddle under your feet.

All actions must be careful. Sudden movements can damage the splines on the input shaft of the diaphragm.

Automatic transmission repair

It is better to do automatic transmission repair with your own hands, having it at hand proprietary manual and a printed diagram of the gearbox. First you need to inspect all the systems that serve the gearbox, mounts and blocks. Then we proceed to the repair. For this:

We disassemble the gearbox, wash and dry the parts and check them for defects.
We change all gaskets, seals, as well as worn out parts.
Remove the inhibitor block and sump. We clean out the dirt inside. It looks like metal magnetic shavings.
We remove the wiring of the ring from the plug and push them inside the plug.
Remove the valve body, loosen the brake band bolts. We wash the valve body.
We check the clutches, gears and planetary gears for wear. We will replace it if there is such a need. All internal rubber bands must be changed!
We open the oil pump. We check all the details, especially the filter. We change what has already served its term. We use the manual so as not to swap parts.
We take out the valves and springs. We wash the valves. Their sticking can be the reason for incorrect operation of the automatic transmission. Replace the accumulator springs if they are broken.
Putting everything back into place. It is important not to confuse anything!
We replace rings and friction bolts.
We check the gear shift assembly and the large piston and put the oil pump in place.

Assembly takes place upside-down.

There are some points that it is advisable to take into account when repairing. Often a transmission problem is related to the filter. It will not be possible to change it without removing the valve body. And when it is removed, the gasket breaks. To replace it, you will need to disassemble the valve body completely. The same applies to the accumulator spring from first to second gear. A special stopper does not allow you to remove it without disassembling the valve body. All valve body gaskets are very similar, do not mix them up. Assembling the valve body, we tighten it with a torque wrench. It is important not to overtighten here.

Post-repair installation of automatic transmission

If all the breakdowns are eliminated, we install the automatic transmission. The moment is responsible, haste is inappropriate here. During these works, the following recommendations should be adhered to:

When installing the automatic transmission in its place, the diaphragm is checked for end runout using an indicator head. If such a defect occurs, then it must be replaced.
The radiator is flushed until the gasoline is clean. Then pour in a liter transmission oil in the gas turbine engine and put it on input shaft... You need to achieve a secure connection and a complete fit. Then you need to dock the engine with the box along the guide centering pins. The crankcases must abut completely.
Tightening the bolts in the box is next stage... After that, the absence of gaps along the entire plane is checked. After connecting all the highways, the correctness of the connections is checked.
At the final stage, oil is poured and the operation of the automatic transmission is checked at low engine speeds.

Beginning the installation of the box, be sure to check for the presence of centering pins on the crankcase flange - there should be two of them. If at least one is missing, the automatic transmission cannot be attached.

Automatic transmission repair and diagnostics do it yourself - not an easy but feasible task. When choosing, novice car enthusiasts believe that repairing it at home is impossible. This is not true. But before deciding to carry out such important work at home, you need to weigh all your possibilities. Then you will not be in for unpleasant surprises during the renovation.

16 december 2018

The automatic transmission is distinguished by its reliability and long service life. This will be confirmed by every owner of a car with automatic transmission. Thanks to innovative technologies, the machine has long ceased to yield to its mechanical counterpart in terms of strength.

However, even the most reliable mechanism fails sooner or later. Whatever one may say, the laws of physics and the force of friction have not been canceled yet by a single engineering company. In this article, we will consider the main malfunctions of an automatic transmission and options for eliminating them.

What are the automatic transmission malfunctions?

It is difficult to imagine the modern world without a car with an automatic transmission. Frequent traffic jams and traffic lights at every intersection made the automatic machine an indispensable thing for moving around cities. Perhaps that is why most of the significant concerns are gradually abandoning mechanics in favor of automatic switching gear. This trend is gradually coming to our country, and with it the problems associated with automatic transmission.

Any current design in a car has two principles of operation: mechanical and electronic. Automatic transmission is no exception. Physical gear shifting is carried out by mechanisms, and algorithms are calculated by the software component. Therefore, all causes of breakdown are divided into two large groups:

mechanical breakdowns. They occur in the hydraulics and physical drives of the transmission;
electronic system crashes. Malfunction of programs or electrical parts of the machine.

Let's analyze each of these points separately.

Mechanical and hydraulic problems

Most often, with mechanical faults, the following elements break:

wear of the shafts or gears of the mechanism;
damage or wear of couplings, discs, brakes inside the transmission;
problems in the operation of the torque converter;
wear of the hydraulic block;
clogging of the oil channels of the box;
failure of the oil pump.

From the list above, you can see that the main problems in the mechanical part begin with wear of parts or the use of unsuitable oil. It is worth noting that this is a real stumbling block for automatic transmissions: more often motorists simply run out of resources for the internal structures of the box. This once again proves the security of this type of transmission.

It is very important to detect and fix automatic transmission problems early.... Otherwise, one malfunction will give rise to another, forming a kind of mutual guarantee. So, when the coupling is worn, the oil transfer channels are clogged, and they will already lead to problems with the pumping system. Having delayed with one problem, some motorists come to services with an almost completely destroyed machine gun. But we'll talk about the reasons a little later.

Electronics and possible problems

Automatic transmission malfunctions do not bypass the electronic internals. We list common examples of broken elements:

breakdown of electronic units, automatic transmission controller;
improper operation or broken transmission sensors;
malfunction or deterioration of electrical wiring;
closures;
failure in the operation of machines, phase devices.

The automatic transmission is designed in such a way that even in case of failure electronic control the car will be able to continue its course. In this case, the backup algorithms of the programs are started: the transmission goes into emergency operation. More often, the car automatically switches to 3rd speed. This helps the driver to get to the nearest service and eliminate the cause. Modern systems notify the owner of electronics problems.

From fans of manual transmissions you can often hear that if an electrical component breaks down in a car with a machine gun, then, unlike mechanics, movement on it is impossible. As we can see from the example above, this judgment is not true.

Reasons for the breakdown of the machine

There are the following main reasons for a failure in the automatic transmission:

resource consumption or wear of parts. The most commonplace, but also the most common reason. Even neat and careful owners come to this situation sooner or later;
use of poor quality or unsuitable oil. Another common mistake. In pursuit of economy, drivers use uncertified oils. This becomes the reason for the rapid breakdown of the automatic transmission;
service in the service with low-quality consumables. Here again, the savings can be deliberate;
inexperienced or irresponsible mechanic. You will never guess how decently a person will approach working with a car. Try to contact trusted specialists;
habits of using the machine. Many of these habits lead to wear and tear on parts. A striking example is this frequent aggressive driving... But the challenges aren't just limited to governance. Also, a short warm-up of the car in the cold leads to a malfunction.

Thus, most of the reasons depend on the car owner himself. If something remains unclear to you, refer to the car manual or the appropriate service. There you will learn the nuances of operating your car brand and protect the automatic transmission mechanism from breakdowns.

Signs of problems with the machine

Of course, you will have to go to a professional service to accurately diagnose automatic transmission problems. However, there are visible signs of automatic transmission malfunction or structural malfunction. Let's consider some bells and obvious faults:

Automatic transmission does not change gears. This is definitely a noticeable problem with the box. In this case, the speed may not turn on at all and remain neutral. But most often the car switches to first gear in position D. In most cases, it is accompanied by characteristic sounds and triplets of the car;
automatic transmission slipping. If the transmission slips, it immediately catches the eye: the car picks up hard speed when the revs increase, makes a characteristic sound when the gear is reset. If you notice something like that, contact the service;
in case of malfunctions in the valve body, the car begins to move with characteristic abrupt jerks;
overheating of the transmission, a small amount special liquid in the box, insignificant internal lubrication pressure are direct signs of failure. However, they are available on machines with appropriate sensors or instruments.

It is worth saying that in general, any unpleasant and uncharacteristic sound is a reason to turn to the master... This also applies to all kinds of disturbances in the course of the machine. Fortunately, today an initial cursory inspection of a car is not so expensive.

Even if you do not see the obvious reasons for contacting repairs, regularly undergo maintenance and inspection of the car. It is not recommended to lengthen or neglect maintenance intervals. Yes, you will save money at first, but in the future, problems, in particular with the box, will cost you a pretty penny.

Ways to troubleshoot malfunctions

We have examined the causes and symptoms of the vending machine malfunctions. Now it's worth saying a few words about the fix. Let's make a reservation right away that there are two methods for solving transmission problems:

Self-repair or prevention.
Contacting specialists.

Needless to say, the first option is cheaper and preferable for every car enthusiast. However, in reality, not all work failures are resolved by hand. For example, if the automatic transmission does not switch gears or slips, then the car will be assisted exclusively by a qualified specialist.

Let's select specific examples for both situations.

Independent solution

We will bring a number of corrected errors into the appropriate form: the common cause is possible problems- ways to eliminate them.

1. Violation of adjustments or malfunction of the gearshift component:

the car moves in the P box mode;
the speed letter on the panel does not correspond to the set one.

Remedy: Diagnostics and replacement of a faulty part, you can repair it yourself according to the instructions provided.

2. Leakage of oil from the automatic transmission. A common problem with a box:

fastenings of mechanisms inside the transmission move away on their own;
destruction or unusability of oil seals and gaskets.

Self-repair methods:

tightening of bolts, purchase and installation of new seal rings;
lowering the oil level in the automatic transmission.

3. Noise or abnormal sounds during box operation:

the machine itself changes gears;
switching positions is very difficult;
the car does not respond to switching and does not move.

Remedy: Measure the oil level and add the correct amount.

Only the main cases of minor breakdowns inside the automatic transmission are given. If your situation fits at least one of the points, read the instructions for the car. Inside you will find step-by-step steps to solve the problem. In the future, it is recommended to turn to professionals.

Repair in service

Let's write down the problems that require contacting a qualified workshop.

1. The car remains in place for any action with the gearbox mechanism. There is no reaction or the slightest movement.

there is little oil in the system;
clogged valves or rings;
malfunction of the waterworks;
breakage of the filter;
malfunction or wear of the main gear.

2. Shocks and shocks when changing gears.

wear of couplings;
hydraulic block valve malfunction;
damage to the valve spring.

3. Unhealthy noise in the differential area of the machine

bearing or gear wear;
some mechanisms are jammed or loose.

Many problems are more often identified at the stage of disassembling the transmission. Thus, a trip to the service is a priority for a serviceable car.

Unlike mechanical box, the machine is less demanding on operating conditions. It is almost impossible to independently burn the box with rapid wear on high revs... An automatic algorithm will automatically up and down gears. This system is especially suitable for novice or inexperienced drivers.

The first and basic rule for using automatic transmission is to warm up the car before driving. This is especially true for our country, given the long periods of low temperatures. In the cold, the car needs to be warmed up for at least 10-15 minutes. Therefore, if you are in a hurry, think - perhaps rushing will cause you more problems than being late.

Don't use normal switches too often. This often affects motorists who have switched to an automatic transmission with a manual transmission. When stopping at intersections and traffic lights, do not put the gear in neutral or sector P. Also, do not make limited maneuvers using the gearbox. Better use idling auto.

Similar advice would be to use reverse speed only after the machine has come to a complete stop. Otherwise, the gears and mechanisms inside the box will move.

All preventive maintenance and car care comes down to checking and timely oil change. This must be done on the mileage indicated in the instruction manual. As a rule, this is 7.5 - 15 thousand kilometers. Under severe operating conditions - 5,000 km.

Use quality oils, on time auto service and do not strain your workhorse. Then your vehicle will serve you for a long time and faithfully.

The most reliable of all varieties automatic transmissions, but it is not so. If used incorrectly, the automatic transmission can be "killed" very quickly.

Incorrect operation of the automatic transmission should be understood as:

sporty driving style, characterized by sharp acceleration and braking with maximum torque transmission;
systematic overheating of the gearbox caused by traffic in traffic jams, high ambient temperatures, slipping, towing another car or trailer;
driving on an unheated gearbox in cold weather;
violation of the frequency of service, incl. oil change, oil filter.

But even with proper operation, over time (100-150 thousand km of run), physical aging of individual elements of the gearbox occurs and their failure occurs.

Automatic transmission malfunctions can be conditionally divided into two large groups:

malfunctions of the electronic control system of the transmission;
malfunctions of the transmission itself.

Malfunctions of the electronic control system of the transmission

The main malfunctions of the electronic control system of an automatic transmission are:

In the electronic control system, the fault diagnosis is carried out by the control unit. It controls many parameters: signals of input sensors, resistance of output circuits, gear ratio of the gearbox, by comparing the sensor signals at the input and output of the automatic transmission.

If the monitored parameters go beyond the permissible limits, the control unit writes into the memory the so-called. malfunction code(DTC, Diagnostic Trouble Code), which is a specific sequence of numbers. The reading of the codes is carried out by special diagnostic equipment - a scanner, and the process itself is called computer diagnostics.

Almost all malfunctions of the electronic transmission control system are determined using computer diagnostics. The situation is more complicated with electrical wiring faults, which cannot always be determined by the scanner. This group of faults is diagnosed by visual inspection and the ringing of the wiring.

When a malfunction occurs in the computer's memory, the control unit acts in accordance with the programmed program. Electronic system control is designed in such a way that in the event of a failure in the data transfer process, it uses replacement signals to ensure operability. It is called emergency work program.

So, the signals from the speed sensor at the input of the automatic transmission are replaced by the signals from the crankshaft speed sensor, the speed sensor at the automatic transmission output - the wheel speed sensor, the temperature sensor working fluid- coolant temperature sensor.

To protect the transmission from overheating, the control program shifts the transient shift modes to higher engine speeds and also reduces engine torque.

If the actuators or the control unit itself fail, the transmission control system switches to emergency operation... In emergency mode, the 3rd gear is forcibly included or saved (if it was included). Emergency mode does not imply further operation of the car, but allows you to drive to the nearest workshop.

In addition to malfunctions of the control system, the transition of the gearbox to emergency mode may indicate malfunctions of the mechanical or hydraulic part of the automatic transmission.

Malfunctions of the mechanical and hydraulic part of the automatic transmission

In accordance with the design, the malfunction of an automatic transmission can be divided into the following groups:

malfunction of the torque converter;
malfunctions of friction clutches and brakes;
malfunctions of the distribution module (hydraulic block);
malfunction of the oil pump.

Automatic transmission malfunctions are accompanied by certain external signs, which include:

slippage (weak dynamics);
jerks (blows) when shifting gears;
lack of movement forward or backward;
noise during operation (creak, rattle, rumble, whistle, knock, etc.);
leaks of working fluid.

When diagnosing faults, it should be borne in mind that several transmission faults may correspond to the same external symptom. Of all the external signs, the absence of movement forward or backward indicates the most serious violations in the mechanical part of the gearbox.

Modern automatic transmission is complex technical system, including multiple connections between structural elements. Therefore, the failure of one element usually entails a malfunction of the other. For example, wear of the friction clutch linings leads to clogging of the oil and, accordingly, the valves and channels of the hydraulic unit. Clogged valves and channels, in turn, leads to incomplete operation of the friction clutches, their heating and premature destruction. Here is such a cycle.

The final diagnosis of a faulty automatic transmission assumes an integrated approach, which includes sequential computer diagnostics, special tests, oil quality assessment, disassembly and troubleshooting of the box.

The main converter malfunctions

The main faulty friction clutches and brakes wear of friction linings and a violation of the seal of the drive hydraulic cylinders. Signs of these malfunctions are slippage, incl. slippage on a warm gearbox, shifting gears with jolts (impacts), metallic noise, lack of movement. It must be remembered that the process of wear of the friction discs is irreversible.

The main junction module malfunctions and their corresponding signs are shown in the table.

Oil pump malfunctions accompanied by an increased noise level, slippage, lack of movement.

In conclusion, it should be noted that there is no automatic transmission that is ideal in terms of reliability. Each automatic transmission model has its own weak spots and, accordingly, their "sores". Manufacturers know this and are constantly improving the design of an automatic transmission.

Automatic transmission malfunctions. Automatic transmission malfunctions - symptoms and remedies Worn or broken clutch piston cuffs