Is it possible to drive with a faulty automatic transmission? Typical automatic transmission faults and their elimination. Features of automatic transmissions and their most common malfunctions
It is the most reliable of all varieties automatic transmissions, but this is not entirely true. If not correct operation An automatic transmission can be “killed” very quickly.
Improper operation of the automatic transmission should be understood as:
- sporty driving style, characterized by sharp accelerations and braking with transmission of maximum torque;
- systematic overheating of the gearbox caused by driving in traffic jams, high outside temperatures, slipping, towing another car or trailer;
- driving on a cold gearbox in cold weather;
- violation of service intervals, incl. changing the oil and oil filter.
But even with proper use, physical aging occurs over time (100-150 thousand kilometers). individual elements gearboxes and their failure.
Automatic transmission malfunctions can be divided into two large groups:
- malfunction of the electronic transmission control system;
- malfunction of the gearbox itself.
Malfunctions of the electronic transmission control system
The main malfunctions of the electronic control system of an automatic transmission are:
In the electronic control system, fault diagnosis is carried out by the control unit. It controls many parameters: signals from input sensors, resistance of output circuits, transmission ratio, by comparing sensor signals at the input and output of the automatic transmission.
If the monitored parameters go beyond acceptable limits, the control unit records the so-called. fault code(DTC, Diagnostic Trouble Code), which is a specific sequence of numbers. The codes are read using a 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 detected by a scanner. This group of faults is diagnosed by visual inspection and testing the wiring.
If a malfunction occurs in the computer memory, the control unit acts in accordance with the programmed program. The electronic control system is designed so that if there is a failure in the data transmission process, it uses replacement signals to ensure operation. It's called emergency work program.
Thus, the signals from the rotation speed sensor at the automatic transmission input are replaced by signals from the crankshaft speed sensor, the rotation speed sensor at the automatic transmission output - wheel speed sensor, temperature sensor working fluid– coolant temperature sensor.
To protect the gearbox from overheating, the control program shifts transient gear shift modes to higher speeds and also reduces engine torque.
In case of failure actuators or the control unit itself, the gearbox control system switches to emergency operation. In emergency mode, 3rd gear is forcibly switched on or saved (if it was switched on). Emergency mode does not involve further operation of the car, but allows you to get 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 parts of the automatic transmission
According to the design, automatic transmission faults can be divided into the following groups:
- torque converter malfunction;
- malfunctions of friction clutches and brakes;
- malfunction of the distribution module (hydraulic block);
- oil pump malfunction.
Automatic transmission malfunctions are accompanied by certain external signs, which include:
- slip ( weak dynamics);
- jerks (impacts) when changing gears;
- no forward or backward movement;
- noise during operation (creaking, grinding, roaring, whistling, knocking, etc.);
- leakage of working fluid.
When diagnosing faults, it should be taken into account that the same external sign may correspond to several gearbox faults. Of all the external signs, the lack of movement forward or backward indicates the most serious problems 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 the failure of another. For example, wear of friction clutch linings leads to clogging of the oil and, accordingly, the valves and channels of the hydraulic unit. Clogging of valves and channels, in turn, leads to incomplete operation of friction clutches, their heating and premature destruction. This is the cycle.
Making a final diagnosis of a faulty automatic transmission requires an integrated approach, which includes sequential computer diagnostics, special tests, oil quality assessment, disassembly and troubleshooting of the gearbox.
Basic torque converter malfunction
Main malfunctions of friction clutches and brakes are wear of the friction linings and failure of the seal of the drive hydraulic cylinders. Signs of these malfunctions are slipping, incl. slipping on a warm box, gear shifting with shocks (impacts), metallic noise, lack of movement. It must be remembered that the wear process of friction discs is irreversible.
Basic distribution module malfunction and the corresponding signs are given in the table.
Oil pump malfunctions accompanied increased level noise, slipping, lack of movement.
In conclusion, it should be noted that there is no ideal automatic transmission in terms of reliability. Each automatic transmission model has its own weak points and, accordingly, their “sores”. Manufacturers know this and are constantly improving the design of automatic transmissions.
Automatic transmission malfunctions are the most difficult case to diagnose. The problem is that each manufacturer has its own technology, and therefore design. Therefore, diagnosing automatic transmission faults is a practically unoccupied niche, in which there is a large shortage of specialists.
Contents of the article:
Gearbox, no less important composite car, rather than the engine or steering. As with every mechanism, the gearbox has its drawbacks, in particular the automatic transmission. There are many people who have positive and negative views on automatic transmissions. Let's consider the most frequent breakdowns automatic transmission and nuances for diagnostics.
Signs of automatic transmission malfunction
During vehicle operation, the vehicle's transmission is subject to heavy loads, which can result in breakdowns. Car manufacturers are doing everything possible to increase the service life of these units, but there are no eternal parts. There are a wide variety of signs of malfunction that give the owner important information about a unit failure. So, for example, when the valve body fails, then significant shocks and jerks occur during gear shifting. Such tremors are progressive in nature and are barely noticeable in the initial stages. There are a sufficient number of types of shocks and they all indicate various breakdowns.
If you find such problems, you should contact a car service center, whose specialists will help determine the exact cause and repair it. necessary work. There are cases when the malfunction is expressed in the complete absence of gear shifting or by blocking the operation of a certain gear. In such a situation, any operation of the car is prohibited; you should use the services of a tow truck.
Some faults are detected using built-in sensors, such as:
- overheating of automatic transmission parts;
- minimum level transmission fluid;
- failure of other sensors responsible for the correct operation of the unit;
- problems with gear shift mechanisms.
However, you should not completely rely on sensor notifications, because most reports of breakdowns are not specific. In some cases, even a professional diagnostic computer cannot make an accurate diagnosis of a breakdown. In such cases, the technician will need to dismantle the assembly; after opening, he will accurately determine the cause of the breakdown.
The main causes of automatic transmission malfunction
Having dealt with the main symptoms of automatic transmission malfunction, you should find out the causes and methods of eliminating them. The main causes of malfunctions include:
- problems with the lever linkage;
- leakage transmission oil;
- malfunction electrical unit control unit (ECU);
- some problems with the valve body;
- torque converter failure.
Problems with the automatic transmission lever rocker
In cars equipped with an old-style automatic transmission (in which the selector is mechanically connected to the transmission), a frequent cause of breakdown is the rocker. As a result of a broken linkage, the process of switching transmission modes becomes impossible. These malfunctions appear in the form of difficult shifting of the automatic transmission lever. IN end result the lever simply stops moving and the linkage needs to be replaced. In some car modifications, such work is performed without removing the box itself, which greatly simplifies the repair process.
Transmission oil leak
One of the more common malfunctions is oil leakage from gaskets and seals. In order to detect leaks on the pallet or the box itself, it is enough to periodically drive onto an inspection ditch or overpass. If obvious oil leaks are detected in the automatic transmission area, you must immediately contact a specialist. Eliminating such problems will not be difficult; it is necessary to replace the sealing gaskets and transmission oil.
Electrical control unit malfunction
In some cases, improper operation of the automatic transmission may be caused by a breakdown of the gearbox ECU. Symptoms of such a malfunction are as follows: the unit will incorrectly select the speed to change gears, and in some cases the transmission will be blocked. If such a malfunction occurs, the only correct solution is to replace the ECU with a new one.
Some problems with the valve body
Problems with the valve body can occur as a result of improper operation of the automatic transmission. For example: when a motorist winter period does not warm up the car, but immediately starts moving, as a result of which the valve body may break. Symptoms of the malfunction are as follows: shocks, impacts, and in some cases, the car’s refusal to drive. Modern cars equipped with an on-board computer will alert the owner about problems with the valve body.
Torque converter failure
Obvious signs of a torque converter malfunction appear as follows: vehicle vibration, rustling sounds, and when changing the oil, chips are found in the transmission pan. Such malfunctions can be eliminated exclusively by repairing the automatic transmission.
How to avoid problems with automatic transmission
Malfunctions in automatic transmissions can be divided into two types:
- Physical wear of parts;
- Incorrect operation of the transmission.
It is also worth noting that original gear oil should be used. The use of low-quality oil can lead to failure of solenoids, the work of replacing which is somewhat difficult and quite expensive. It must be recalled that cars with automatic transmission are extremely critical to aggressive driving style.
At long-term operation engine on high speed Automatic transmission clutches can wear down and quickly burn out. The difficulty of repairing cars with an automatic transmission is that to determine the breakdown it is necessary to open the transmission. Conduct do-it-yourself repair Automatic transmission is not recommended; it is better to entrust this matter to professionals at specialized centers.
Diagnostics of automatic transmission faults
Specialists from specialized car services distinguish 3 types of diagnostics:
- "Hear". Quick diagnostics to identify hearing problems. Experienced car service technicians can identify minor faults by ear by how the mechanism works. Often, such malfunctions include work on cleaning the sensor or adding oil to the system.
- "Touch". The second type of diagnosis among specialists is called “touch”. Often, such work includes electrical wiring diagnostics, which takes a little time. A more serious problem is determined by removing the box tray. Without removing the automatic transmission, the technician will be able to determine the oil pressure in the system, as well as clear error codes.
- "Disassemble." When obvious problems are detected in the operation of the transmission, and simple methods cannot be done, then disassembly of the unit will be required. Such work is typical for cars with mileage of more than 200,000 km.
Despite all the above diagnostics, a 100% result in identifying the cause of the malfunction is achieved by opening the automatic transmission.
An automatic transmission is one of the main components of a vehicle, the breakdown of which can cause significant losses for the motorist’s budget. Therefore, even a novice motorist must understand what automatic transmission faults exist and how to identify them. You can find out more about the main breakdowns of this unit, the causes and ways to eliminate them on our resource.
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Signs of problems with automatic transmission
It is no secret that during the operation of a vehicle, heavy loads are placed on the automatic transmission, which can cause gearbox failure. And although lately automobile manufacturers They are doing everything to increase the service life of these units; anyway, the “machine” is considered one of the most vulnerable units. As for malfunctions and their symptoms, they can be very diverse. For example, if there is a breakdown in the operation of the valve body, shocks and jerks may occur during gear shifting. However, shocks can be very different, there are many types of them and they all indicate different breakdowns.
Especially if the breakdowns progress, the shocks and jerks may change. If such problems arise in the operation of the unit, the vehicle owner should troubleshoot as quickly as possible or contact specialists. It should also be noted that malfunctions of the automatic transmission can be expressed in the inability to switch one speed or another. Or in complete blocking of gears. If you are faced with a similar problem, then under no circumstances should you use your vehicle, otherwise the problem may worsen.
Sometimes automatic transmission malfunctions can be determined using regulators and other sensors with which the unit is equipped.
Such devices allow the motorist to identify and warn him about:
- insufficient level of transmission fluid in the system;
- insufficient pressure of the working lubricant;
- overheating of the automatic transmission;
- failures of other sensors;
- problems with switching modes.
Actually, the same thing can be done on-board computer, issuing a message to the driver on the control panel by activating Check lights Engine. However, it should be noted that most of these reports of transmission failures are inaccurate. Accordingly, only a complete computer diagnostics or disassembly and reassembly of the unit. It should also be noted that in some individual cases even diagnostics will not help, resulting in the need to dismantle the transmission.
Reasons
If the signs of an automatic transmission malfunction are clear to you, then before we look at how to eliminate them, let’s look at the main reasons. A list of the main causes of automatic transmission failures is presented below. Only based on the reasons can you determine what to do next with the car.
Lever link
If you own a car with an older type of automatic transmission, in which the selector and transmission are directly connected mechanically, then know that the lever linkage often causes problems. The gear selector lever sometimes breaks, making changing modes impossible. As practice shows, in most cases such breakdowns are solved by replacing the lever and rocker.
As for the signs, problems associated with the rocker are manifested by difficulty moving the automatic transmission lever. As a result, the selector may stop moving altogether, and accordingly, activating one or another mode will be impossible. In some units, work to replace the rocker can be carried out without removing the transmission.
Oil leak
Often in practice, automatic transmission malfunctions are caused by transmission fluid leaking from the system, and the leakage is mainly observed from under the rubber seals. Therefore, we recommend that all motorists periodically perform a visual inspection of the unit in a pit or overpass. If you notice any signs of leakage, this indicates the need to urgent repairs. As a rule, such problems are solved quickly; their elimination is not difficult, since it is solved by replacing the rubber bands and replacing the working fluid.
Always visually check the condition of the unit, this will help identify a transmission malfunction.
Control unit
Sometimes incorrect operation automatic transmission may be due to problems in the operation of the control unit. In particular, this block may incorrectly select the speed for switching modes, or it may completely block the operation of the unit. As practice shows, repairing the control unit usually does not help much. Therefore, such problems are usually solved solely by replacing the device, as well as the cables adjacent to it.
Valve block failures
Valve block failure is also a common problem. For example, if the transmission is used incorrectly. If a motorist does not warm up the car in cold weather before leaving, but immediately starts moving, then the valve body will be the most vulnerable unit in this case. Such malfunctions manifest themselves in the form of shocks, jolts or vibrations, sometimes vehicle It may not start at all. If you have modern car, then you can find out about a valve body failure from a message from the on-board computer.
Torque converter malfunctions
As practice shows, such breakdowns can only be solved by repair. As for the cost, in the case of a torque converter it will be significantly lower than with a valve body and ECU. If the torque converter is not working correctly, then you will hear knocks, vibrations, rustling, you will notice how the dynamics have deteriorated, and when replacing the working fluid, you will notice metal shavings in the pan.
How to avoid problems?
We have talked about the causes and signs of breakdowns, now we will dwell in detail on how to eliminate them. It should be noted right away that all the reasons are conditionally divided into those caused by mechanical wear and those that appeared as a result of improper operation of the car. In practice, many car enthusiasts do not always change the working fluid in the box on time; over time, the lack of lubrication can cause the unit to overheat. As a result, all moving components of the transmission break down much faster; the only way to eliminate them is to replace them. Therefore, car enthusiasts with an automatic transmission should periodically diagnose the lubricating fluid in the system.
Another way to eliminate possible problems is to regularly warm up the gearbox in winter, which will relieve the car owner from problems associated with the lubrication of moving components. As a result of using low-quality oil, solenoids suffer, and replacing them can take not only a lot of time, but also considerable financial costs. Do not forget that such transmissions are always sensitive to aggressive and fast driving styles. Moreover, when permanent job motor on increased speed Transmission clutches wear down and burn out very quickly. Therefore, we recommend that you refrain from this driving style.
Another difficulty in eliminating transmission breakdowns is that in most cases the fault can only be identified by dismantling and disassembling the automatic transmission. Accordingly, the transmission will need to be removed from the car. As practice shows, it is very difficult, almost impossible, to carry out high-quality repairs at home, so in such cases it is better to contact specialists. Repair of transmission elements consists of replacing failed components. Here it should be noted that, regardless of the method of eliminating the breakdown, repairing an automatic transmission will always be more difficult than a “mechanical” one due to design features unit.
How is it diagnosed?
Troubleshooting starts with diagnosing them.
There are several ways:
- Detection of hearing problems. In many cases, diagnosing the operation of an automatic transmission may involve hearing a malfunction. As a rule, if the unit starts to work differently, the motorist will immediately know about it. Troubleshooting easy problems involves cleaning one or another regulator from oil or replacing the working fluid. Sometimes all you need to do is add oil to the system.
- The second type of diagnosis is referred to by specialists as “touch”. At this level, electrical wiring diagnostics often help identify a breakdown; this procedure usually takes a few minutes. If the damage is more serious, then you can try to detect it when dismantling the pallet. In addition, without removing the unit, the technician can determine the malfunction by measuring the pressure in the system or reading fault codes.
- The third type of fault diagnosis and elimination is dismantling and complete overhaul of the unit. If the gearbox goes into emergency mode, then to identify the breakdown it will only be necessary to disassemble the transmission. As a rule, the need for dismantling and disassembly arises in the case of units that have traveled more than 200 thousand kilometers. Usually, with such a mileage, it becomes necessary to replace the clutches.
Table - an assistant for determining the breakdown of the machine
| Signs | Reasons |
| The car cannot move forward, there is slippage, reverse gear works normally. | These signs indicate worn clutches and a forward clutch. The problem may also be a broken piston cup, worn clutch rings, or sticking of one of the valve body valves. |
| Reverse gear does not engage. There are also no third and fourth gears, only the first two speeds work. |
|
| The car does not move forward or backward. If the parking or neutral gear mode is activated, and, in principle, jerks appear at any speed, the gear is engaged, but without movement. |
|
| The car only moves in third gear. | The clutches or clutches are worn out, the piston cups are worn out, the rings are stuck, the valve body valve is stuck. |
| Jerking appeared when cold. | The solenoids and valve body are dirty, sometimes it’s due to bad oil. |
| Reverse gear does not engage. | Wear nerdy years, piston cuff, rod. |
| The car does not move at all, the gears are switched on without jerking. | The torque converter does not work, the pump gear is broken, there is no oil in the system, the filter is clogged, the solenoid or valve is broken. |
| There was noise during operation of the unit, vibrations, knocking. The sounds get louder as the speed increases. | The bearing needs to be replaced. |
| Only reverse, first and second gears are engaged; after warming up, all of them can be engaged. | The problem is the solenoid or a clogged valve body. |
| Speeds are activated at higher speeds. | You need to adjust the throttle valve cable, clean the filter or replace the valve. |
| The car generally drives normally, but when going uphill it starts to slip and slow down. |
|
| When you press the gas, the speed does not change. |
|
| When starting from a stop, slippage appears, but no other problems are observed. |
|
| Slipping occurs when switching all gears. |
|
| When the car warms up to operating temperature slippage begins, the car may not move at all. |
|
| There is noise in neutral gear. | The clutches of one or more drums are worn out. |
| The transmission fluid began to foam, and the overall color of the oil was unnatural. Sometimes there is slipping. | Most likely, the cause is moisture getting inside the unit. |
| Low pressure of working fluid. |
|
| Metal particles were found in the pan. | The sliding bearing may be worn out or the planetary gear will soon fail. |
| Metal grinding when moving. | It is necessary to replace the gears or differential bearing. |
Learn in detail about the main malfunctions in the automatic transmission and recommendations for use from the video.
Automatic transmissions are very complex mechanisms consisting of a huge number of parts. Determine exactly what possible problems with automatic transmission occurred in this particular case, it is possible only with a complete disassembly of the automatic transmission.
Automatic transmission cross-section
First, you need to clear the error codes of the self-diagnosis system and decipher them. In addition, you can ring the chains, measure the pressure, and do a driving test. However, such diagnostics and procedures rarely give an accurate picture - the box must be dismantled and disassembled.
Repairing an automatic transmission indiscriminately is similar to treating a patient based on his external symptoms and the information that he himself conveyed to the doctor. That is, treatment without any tests. And in medicine, for each symptom there can be several hundred diagnoses.
If the automatic transmission behaves strangely or an error appears chaotically, you can check the cables, change the oil and accurately set its recommended level. This can help with modern super-precise BMW automatic transmissions, for example, or tired automatic transmissions with a mileage of more than 200,000 kilometers.
Also, without dismantling, you can inspect the valve body, its sensors and cables, which could also be the source of the automatic transmission malfunction. However, for cars with more than 120,000 miles or for those that do not come out of emergency mode, everything is unlikely to end with such simple procedures.
Determining parts that need to be replaced “by ear” or in some other magical way without opening the box is highly not recommended.
The most common reasons premature breakdown of the machine is a violation of the rules of its operation. Actions that definitely lead to automatic transmission malfunction:
- Aggressive driving and slipping;
- Negligence regarding the condition of the transmission fluid, filter, failure to perform maintenance on time;
- Untimely change of consumables: oil seals, seals, solenoids and their wiring.
All this leads to approximately the same picture - oil starvation inside the box and increased wear of its parts.
After 120,000–200,000 kilometers, significant wear of parts is observed in any box and is always necessary major renovation and diagnostics, as the first automatic transmission malfunctions begin. If you don’t do this, the automatic transmission will be able to drive for some more time, but will still stop at one “wonderful” moment.
Repairing an automatic transmission with your own hands is quite difficult, but it is quite possible if you have the necessary knowledge, skills, tools and space. For the most part, automatic transmissions are equipped with comprehensive drawings and repair and diagnostic manuals, which can be found on the Internet.
Basic gearbox faults
Leaking seals, rings and bushings. An absolutely normal situation after 200,000. Automatic transmission malfunctions arise due to simple wear and tear and obsolescence of parts. The sealing elements become tanned, crack, lose elasticity and begin to leak oil. This little nuisance signals to the car owner that the torque converter clutch has worn down to the adhesive layer and now does not perform its function. It begins to slow down more, slip and overheat terribly, transferring the temperature generated by the friction force directly into the lubricant. Dirty oil clogs the pump, destroys its seal and bushing, which leads to oil starvation and failure. In addition, oil with the remains of the clutch contaminates the valve body. Its channels become clogged and destroyed by abrasive treatment, it begins to work incorrectly and produce abnormal pressure into the box. Wear of the torque converter is preceded by an increase in fuel consumption, loss of vehicle dynamics, leaks on the box and extraneous sounds when the transmission is operating.
Oil on the body is a sign of leaking seals
Previously, sealing elements were made of cast iron, and they survived almost all gearbox mechanisms. Now they are made of rubber and Teflon. Dirty oil can eventually make holes in them, from which oil begins to ooze. The pump tries to correct the situation and pushes more and more transmission fluid there. Therefore, all sealing elements are changed at every opportunity and are produced in sets.
Lack of oil. Due to insufficient oil quantity or pressure, the gearbox mechanisms no longer receive sufficient lubrication. Clutches and steel wheels start to slip. Loss of momentum is a clear sign necessary repairs boxes and ignoring it is very stupid. Major repairs and diagnostics during this period will cost less, and after that the automatic transmission will live for a long time.
If the clutches have completely burned out, then the oil has most likely become almost black and definitely acquired a distinct burning smell. All clutches in the automatic transmission, even unworn ones, were saturated with burnt oil. Actually, it’s too late to repair, just restore or order.
Hydroblock. Previously, hydraulic blocks were practically eternal. They were made of cast iron, there was no fine tuning, calculations and channels calculated down to fractions of a millimeter. A modern valve body is made of soft aluminum with a mass of thin channels, which are very easily clogged with oil debris and are bored out by it, like a file. Now they need to be cleaned periodically; this procedure is usually performed during major repairs. Their service life is one of the shortest among automatic transmission parts, and breakdowns have become commonplace.
Particles of debris either clog spools with solenoids, which leads to their sticking, or bore their channels, which leads to abnormal operation of delicate electronics. The result is always the same - if at least one valve in one of the clutches malfunctions, there is either excess pressure or a lack of it, the clutches begin to slip and die, then dragging along the entire gearbox, which now runs on burnt oil.
Solenoid plungers, clogged with oil, stick, and this leads to their switching every once in a while, jerking and jolting are observed.
But this was not enough for the engineers. They began to produce wiring for the electrical part of the automatic transmission in the form of cables as thick as a human hair, and electronic unit The controls from the car's interior were moved to the hydraulic plate itself. So that it overheats better, obviously.
With the help of such a cunning solution, the automatic transmission electronics have also become a very unreliable place. A small disconnected wire can give very frightening symptoms of a breakdown in the form of jerks and kicks in the gearbox switching.
Signs of automatic transmission malfunction in the valve body
- The box only works well in cold/hot conditions. Solenoid contamination.
- The car cannot move, the reverse works. It's a valve problem.
- Transmissions are not activated. The solenoid is broken.
- Only reverse and first gear work. The valve is stuck.
- Slipping as you move uphill. Solenoid or valve body channels.
- Shocks and jerks during transmission operation. Such breakdowns can cause contamination of the valve body and broken wiring.
- The car stalls when changing to the next gear if you don't accelerate. The valve stuck, breakdowns occurred in the mechanical part of the automatic transmission.
"Iron". Planetary gear, hubs and calipers. As the box and sealing elements wear, vibrations increase. Multiply this by oil starvation and you get completely non-ideal conditions for contacting metal parts. They begin to wear out, crumble, and burst. Failures in the “iron” part of the machine are typical for older machines; they rarely occur on new ones.
Possible hardware failures
- Rumble, vibration, increasing with acceleration. Bearing, bushing or planetary gear fatigue;
- The car is not moving, but there is reverse gear. Wear of the bushing, friction disc, clutch, breakage of the piston cup.
- Reverse and 3-4 gears disappeared. A cut spline connection is added to the points described above.
- There is only no reverse. Fatigue of the brake band, clutch packs, breakage of the piston collar or rod, the entire braking pack is broken.
- The car cannot move and does not respond to the selector switch. Reverse gear does not engage, forward gear engages when the gas pedal is pressed. Death of the torque converter, oil pump, clutches, brake band, pistons, all o-rings. It’s worth checking the dipstick, maybe there’s simply no lubrication in the transmission.
- Shocks when changing the selector position, but the car slips. Not enough oil, the filter is clogged, the torque converter is dead.
- The car slips when climbing hills. Not enough lubrication, wear on clutches, pistons, oil pump.
- Slipping when starting from a standstill. The torque converter, clutch, and clutch seals are worn out.
- The car drives in neutral like it's speeding. Incorrect adjustment of the gear selector, malfunction of its sensor, stuck piston, friction discs stuck together.
- Gear changes occur only at high speeds. Incorrect cable adjustment, the centrifugal regulator valve is stuck, the filter is clogged, the throttle valve is stuck.
- The kickdown is gone. The sensor or its wiring has died, the valve is stuck, the cable is incorrectly adjusted.
- Shocks and jerks when changing gears. Worn clutches or brake band.
- The car moves and starts moving from a standstill with great difficulty. The torque converter died.
- Metallic sounds, hum in the box. Wear of gears, bearings, differential, satellites.
- After the automatic transmission warms up, the car does not drive. Wear of friction clutches.
- The car stalls when changing gears if you don't accelerate. Torque converter.
- Metal particles in the pan. Wear of planetary gear, bearings, satellites, bushings, differential.
- Pieces of plastic in the tray. A bushing, washer, washer or other element has broken.
- Balls in a tray. The bearing fell apart.
Deciphering automatic transmission self-diagnosis system codes
To determine machine breakdowns, there is its own electronic system self-diagnosis, which is combined with the generally accepted OBD-II system.
The control unit is faulty
Control unit errors
The electrical part of the control system is faulty
P0703, P0719, 724
Torque sensor faulty when speed decreases
Incorrect clutch sensor readings
Incorrect readings of the selector position sensor
Selector lever sensor incorrectly adjusted
Incorrect selector sensor readings
Incorrect coolant temperature sensor readings
Incorrect turbine sensor readings
Incorrect shaft speed sensor readings
Incorrect engine speed sensor readings
Incorrect automatic transmission adjustment
Incorrect first gear adjustment
Incorrect second gear adjustment
Incorrect third gear adjustment
Incorrect fourth gear adjustment
Incorrect fifth gear adjustment
Incorrect reverse adjustment
Clutch faulty
Pressure regulator malfunction
The first shift solenoid is faulty
Second shift solenoid faulty
Third shift solenoid faulty
The fourth shift solenoid is faulty
The fifth shift solenoid is faulty
Switch is faulty
The first and second switches are faulty
The second and third switches are faulty
The third and fourth switches are faulty
The fifth and fourth switches are faulty
Incorrect solenoid sensor readings
Normal mode faulty
Broken reverse
Shift solenoid 1–4 faulty
Shift light 1–4 faulty
Reverse gear faulty
Brake sensor faulty
Park and neutral modes are not detected
Temperature sensor not tested
Slip sensor error
All wheel drive error
Torque control unit faulty
Torque Converter Clutch Sensor Error
Electronic pressure regulator error
Errors in shift solenoids
The control unit is faulty
Four-wheel drive switch faulty
Transmission temperature exceeded
CCS solenoids are faulty
During the operation of the car, a significant load is placed on the automatic transmission, which leads to breakdowns of this unit. IN recent years Automakers use fairly reliable and modern automatic transmissions, which has significantly reduced the number of such transmission breakdowns. In most cases, automatic transmissions used today, with proper operation and timely maintenance, may require major repairs after a mileage of no earlier than 150,000 kilometers. The first thing diagnostics begins with is the removal of computer fault codes and their subsequent decoding. Then, ideally, contact a specialist for a more accurate diagnosis.
Automatic transmission malfunctions
They meet completely different signs of automatic transmission malfunction that can give car owners necessary information about the nature of the failure. For example, if there are problems with the valve body, significant shocks appear when changing gears. Moreover, such shocks are progressive in nature and at the initial stages of the breakdown are barely noticeable, and as the problem progresses, such shocks become more and more noticeable. If there are such problems with an automatic transmission, the car owner needs to contact the appropriate service center as soon as possible, whose specialists will carry out all the necessary repair work.
Automatic transmission malfunctions can also be expressed in the complete impossibility of switching gearbox operating modes or blocking operation in a certain gear. In this case, the car owner needs to transport the broken down car using a tow truck. It is not recommended to drive a car with a broken transmission on your own, as this can lead to serious damage to the drive and the automatic transmission itself.
In some cases, a malfunction can be diagnosed using built-in automatic sensors in the automatic transmission. Such sensors indicate insufficient oil pressure in the system, overheating, or problems with gear shifting. At the same time, it must be said that most of these reports of problems with the gearbox are not specific in nature, and it is not possible to make an accurate diagnosis of the breakdown in this case even with the help of a professional computer equipment. The technician will need to inspect the transmission, dismantle it, and only after opening it will he be able to determine the existing breakdown.
Causes of automatic transmission malfunction - typical
Lever links
In old-type automatic transmissions, which had a mechanical connection of the selector directly with the transmission, the automatic transmission lever often fails, which makes it impossible to change the operating modes of the transmission. The repair in this case consists of replacing the broken selector and gearbox rocker. Such breakdowns manifest themselves as difficulty in moving the automatic transmission selector. Ultimately, the lever stops moving and the automatic transmission needs to be repaired. For some modifications of automatic transmissions, this work can be carried out without removing the gearbox itself from the car, which somewhat simplifies repair work.
Oil is leaking
A common malfunction of an automatic transmission is the presence of oil leaks from under the sealing gaskets. That is why the car owner is recommended to regularly inspect the condition of the gearbox on a lift or garage pit. If there are any oil leaks on the gearbox itself, you should contact experienced specialists. In this case, eliminating such problems is not particularly difficult and consists of replacing the gaskets and changing the transmission oil.
Control unit
In some cases, there may be problems with the transmission control unit. The control unit may incorrectly select the speed to change gears or independently block the operation of the transmission. Elimination of breakdowns associated with the operation of the control unit and the electrical part of the transmission consists of replacing failed units and control loops.
How to avoid problems?
It must be said that causes of automatic transmission malfunction They can be both objective in nature, caused by physical wear, and can be caused by improper operation of this unit. Many car owners neglect the need to regularly change transmission oil, which leads to problems with lubrication and constant overheating of the automatic transmission. As a result, the moving elements of the box quickly fail and require expensive repairs.
It is also necessary to properly warm up the transmission in the winter, which will eliminate problems with lubrication of the moving elements of the transmission. Low-quality oil damages solenoids, the replacement of which is difficult and expensive. It should also be remembered that automatic transmissions are extremely critical to aggressive driving style. When the engine operates for a long time at maximum speed, the clutches of the automatic transmission can quickly burn out and wear down. That is why it is not recommended to constantly practice an aggressive driving style in a car with an automatic transmission. Difficulty of repair automatic boxes transmission is due to the fact that a breakdown can only be determined by opening the transmission. To do this, it must be removed from the car, which will allow us to determine the nature of the breakdown. It is not possible for most ordinary motorists to carry out high-quality repairs of an automatic transmission on their own, so it is necessary to contact specialized service centers. Repair work consist of replacing damaged elements, which allows you to restore the functionality of the entire automatic transmission. It should be noted that due to the structural complexity, automatic transmission repair is labor-intensive and high-cost.
Table of signs and causes of automatic transmission malfunction
The table of typical automatic transmission faults, which is located at the bottom of the article, presents the most common automatic transmission faults.
The car does not move forward. It's slipping. Reverse speed operates in operating mode.
3. Clutch rings are worn
4. One of the valve body valves is stuck.
No reverse speed. There are only 1st and 2nd speeds, 3rd and 4th speeds are missing.
1. Worn friction disc of a certain clutch.
2. Worn or broken clutch piston cuffs.
3. Worn or damaged clutch oil seal rings.
The machine does not move backwards or forwards. When shifting into P or N, as well as into any gear, there is a strong push, the speed changes - but still without movement.
1. Problem with the torque converter
2. Add oil.
3. Change the oil filter.
Driving only in 3rd speed
1. Worn friction discs, forward clutches.
2. Worn or broken clutch piston cuffs.
3. Clutch rings are worn
4. Valve block valve stuck
The car system considered a malfunction and switched the automatic transmission to Emergency mode. Needs diagnostics and is preparing for repair.
Switching from an unheated gearbox (to a cold one) is made with a push. Contamination of the hydraulic plate or solenoids. Diagnostics and cleaning of the valve body is required. Consumables may need to be replaced.
Absent reverse gear.
1. The brake band is worn out.
2. Wear or breakage of the brake band piston cuffs.
3. The brake band piston rod broke off.
4. Malfunctions of the braking system (package)
The machine does not move backwards or forwards. Switching from “P” or “N” to any speed occurs without a noticeable push to engage the gear.
1. Problem with the torque converter.
2. The oil pump drive gear is faulty. There is no clutch with the torque converter
3. Add oil
4. The filter mesh is dirty (clean).
5. Friction discs, clutch and brake band are worn out.
6. Wear of the cuffs of the pistons of the packages.
7. Worn or damaged clutch oil seal rings.
8. The problem is in the solenoid or in one of the valve body valves.
Increasing hum of the automatic transmission, vibration when driving, and other incomprehensible sounds. They intensify depending on engine speed.
One of the bearings is worn out
There is a reverse gear, the front gears are only engaged in 1 and 2, there is no shifting to subsequent gears. After warming up the automatic transmission and oil, the problem may disappear.
A clogged valve in the valve body or solenoid is stuck.
The car moves with the selector lever in “N” position.
1. Poor adjustment of the cable or lever of the automatic transmission control drive.
2. The piston of one of the clutches is jammed (forward direction).
3. The friction discs are welded with the rest
Gears are switched at high speeds
1. Incorrect throttle valve cable adjustment.
2. Filter clogged
3. Throttle valve malfunctions
The car moves properly, but on a long climb to the last. speed, the machine slips and switches to a lower speed.
1. Check the oil level (ATF) in the automatic transmission
2. Friction discs, clutch and brake bands are worn out.
3. The oil pump is “tired”.
4. Malfunction of the valve body solenoids or maximum wear of the valve body passages.
A sharp press on the gas pedal does not lead to a downshift (kickdown).
1. Faulty sensor or button under the kickdown pedal.
2. The downshift valve is jammed. transmission
Z. Malfunction with the control cable. throttle valve
4. Open circuit of the kickdown sensor.
When the car starts to move, slippage occurs, but after gaining speed it continues to move properly, the automatic transmission switches to other speeds.
1. Extensive wear on the turbine wheel hub splines causes the automatic transmission shaft to slip.
2. Worn or broken clutch piston cuffs.
Slipping when changing gears.
1. Filter clogged
2. Check the oil
3. Pump malfunction
No back and forth movement
The splines in the hub of the turbine wheel of the gas turbine engine are cut off
Strong shocks occur when shifting automatic transmission gears
1. Friction discs are badly worn.
2. The valve body or solenoids channels are clogged.
3. Brake band is worn out
The car slips when driving and jerks when changing gears
Clutch malfunction
No back and forth movement
There is no main pressure
1. The oil pump shaft splines in the torque converter front cover housing are cut off.
2. The splines on the oil pump reactor shaft were cut off.
The vehicle drives normally until the oil warms up. Then slipping begins, and eventually the car remains motionless.
1. The problem is in the friction discs
Note: until the oil is warmed up, its viscosity and pressure are slightly higher than in a hot state, the worn discs are pressed harder against each other, thereby creating traction.
2. The torque converter clutch is worn out. The oil contains a high content of dust from the friction discs. Leads to a clogged filter mesh.
Noise reminiscent of a metal object beating at idle speed
1. Friction. the discs of one of the drums are heavily worn
The automatic transmission will not shift to downshift when “sneaker to the floor”, the speed does not develop in order to increase the speed of the car. There is no kickdown.
1. The problem is related to the operation of the engine.
Lack of downshifting when “slipper to the floor”; the speed does not develop in order to increase the speed of the car. There is no kickdown.
The vehicle drives normally until the oil warms up. Then slipping begins, and eventually the car remains motionless.
The car starts under tension and picks up speed extremely slowly. The problem is also with reverse gear.
1. Check the tightness of the fan blades of the pump or turbine wheel.
2. Breakage of the same blades
You have found iron particles in the pan of your car. The shape is sharp, quite large, exceeding 1 mm. The life of the planetary gear may be coming to an end.
Foaming oil in a machine. Uncharacteristic color of automatic transmission oil. The machine may slip.
Water got inside the automatic transmission
Oil pressure in the line is low
1. Dirty valve body or solenoids.
2. It is necessary to check the oil level
3. Check the relief valve in the oil pump.
After turning on the speed, the car stumbles and stalls. If you increase the speed and apply the gas, there is movement.
1. Check the clutch shift valves
2. Problems with the automatic transmission torque converter
Aluminum particles at the bottom of the pan.
1. The sliding bearing is worn to the limit.
2. The planetary gear may be reaching the end of its service life.
Particles of plastic material detected
1. Plastic bushing
2. Breakage of any plastic element.
Metal scraping
1. Wear of differential gears
2. Wear of the differential bearing.
Magnetized rollers were found in the pallet
1. The thrust roller bearing is destroyed.