Automatic transmission does not respond to gear changes

At some point you realized that the gearbox does not change gears, we will try to figure out the reason. The complex device does not allow you to immediately understand why the automatic transmission does not change gears. The reasons can determine the signs that reflect the behavior of the machine. The most correct and common cause of gearbox failure was the driver. Unprofessional use of the car leads to the fact that sooner or later something breaks. The car has become in demand and useful, not everyone will climb under the hood to check the degree of wear of a particular part in order to prevent breakdown before it occurs.

Lack of transmission fluid

Let's take a closer look at several problems that arise when there is a lack of transmission fluid.

The car does not move and a jolt is felt when the lever is shifted. The main reasons lie in low oil level. The situation can only be corrected by replenishing fluid, perhaps even cleaning the canals.
The automatic transmission does not change gears when going uphill, the gear is downgraded, and the car starts slipping. The higher mode does not turn on. Low fluid levels reduce the vehicle's performance. At the same time, it is worth paying attention to the components (seals, couplings, cuffs) - their condition and degree of wear are significantly reflected in gear shifting. More often than not, the only solution is to change the oil and add fluid.
Clutch slipping when changing the position of the lever on the gearbox indicates problems in the valve body; the reasons may also be hidden in the filter. In this case, it is worth assessing the fluid level and cleaning the filters.

If the automatic transmission does not change gears, the car is constantly slipping, the oil turns into foam with a change in color, then it is worth checking for the presence of water in the gearbox. Liquid ingress negatively affects the functionality of the automatic transmission and foam forms. The second reason why gears do not change when the car behaves like this is clogging of the valve body valves. The technicians will help you disassemble the mechanism and check how the pumps attached to the block work.

Friction disc wear

When changing gear into an automatic transmission from reverse gear, the car begins to slip. The reasons for the machine's behavior are hidden in:

displacement or deformation of friction discs;
rupture of rings or couplings;
valve sticking.

Disc wear can also affect the performance of the transmission. For example, it is impossible to switch to reverse gear, while at the same time moving forward is only possible in second. The reason for this behavior of the car lies in the wear of components; rubber parts are easily worn out when driving. If, during visual diagnostics, all of the specified parts are intact, then further attention should be paid to the clutch drum; perhaps the reason lies there.

You won't be able to drive a car when it's cold. If, when warming up, the car slips at forward and reverse speeds, then you should pay attention to the properties of the oil used, and if possible, it should be replaced. In addition, there may be another reason for this behavior of the car - a clogged filter.

When starting to move, the car slips in place, the movement itself continues, the speed switches perfectly. This may also indicate wear on the friction discs. In this situation, attention should be paid, among other things, to the condition of the torque converter (hub wear is possible) and to the piston cuffs.

The gearbox does not respond to shifting

The hardest thing is when not a single gear shifts completely in the gearbox, either in automatic or manual modes, and there is no push that accompanies the switching. There may be several reasons for this behavior of the car:

valve body malfunction;
lack of transmission fluid;
breakdown of the pump drive gear;
gear shift valve sticking;
brake band wear;
wear of friction discs.

How does the automatic transmission work?

In order for the transmission to work properly and not delay acceleration, you need to understand that an automatic transmission is a more complex unit in design compared to a manual transmission.

It includes several important elements:

planetary system with a set of speeds, responsible for the transition between automatic transmission stages;
a torque converter that acts as a clutch and transmits torque to the wheels;
clutches and mechanisms that provide transition between gears;
valve body - electronic control unit.

The main medium and driving force in an automatic transmission is the transmission fluid - oil. It is supplied under pressure to the torque converter blades, thereby causing the wheels to spin. The pressure with which the liquid presses on the mechanisms depends on the choice of stage.

Actions of motorists

I’m moving on to the most anticipated part - if you are not able to figure out on your own why the gear shift on your gearbox does not engage, then you should contact a car service center, where specialists will carry out diagnostics and educate you about the breakdown, cost and repair time. Checking the functionality of automatic gearboxes is carried out only using computer diagnostics, so you should make sure that the service is available at the car service center.

If after diagnostics no faults are found, and the car continues to act up when changing gears, then you should pay attention to the speed sensors, wiring and scenes.

The backstage can be cleaned quite easily using a hole in the garage or an overpass. The gear and speed sensor is a rather capricious thing. If there is a breakdown, the sensor stops sending signals, which forces the gearbox not to respond to the signals (the gearbox simply sees that there were no signals).

If all the presented methods for eliminating the breakdown are not effective, then the car requires the intervention of a car service guru.

It is worth understanding that there are many more causes of failure, symptoms and methods for eliminating them. You should not delay resolving the issue and allow your car to “cure.”

The box has a rather complex structure, and it is impossible to answer this question right away. But based on some indirect signs, you can determine the essence of the problem and try to fix it yourself.

Problems associated with a lack of transmission fluid

1. When you move the shift lever to any of the positions, a push is felt, but the car does not move either forward or backward. A low oil level can occur due to leaks, a faulty torque converter, or a dirty oil filter. Treatment methods are obvious: replace, fix, clean. And be sure to add fluid to the level.

2. On an automatic transmission, gear shifting in the highest mode during a long climb causes slippage and a premature transition to a lower gear. This occurs because insufficient fluid level reduces hydraulic forces. The cause may also be wear of the clutch discs, wear of the cuffs or o-rings. Replacement and topping up help solve the problem.

What you can do with your own hands

There are a number of simple actions that can prevent the automatic transmission from stalling.

Reasons why the transmission delays the transition between stages	Troubleshooting Methods
Automatic transmission overheating	Lack of transmission oil level, heavy loads on the automatic transmission;
Wear and destruction of internal mechanisms	Clean the magnet, change filters;
Sensor malfunction	Replace them, preferably with original ones

Servicing a car when the automatic transmission is delayed in transmission does not always mean many problems. Some automatic transmissions are capable of exceeding the 500 thousand km mark without major repairs. To check the transmission for gear drag, it is recommended to turn on the kickdown mode. Its name describes the moment itself: push down.

If, while driving a car with automatic transmission, you sharply press the gas pedal, the car goes to a lower gear so that the speed increases as quickly as possible. If this moment passes quickly and without interruptions, then the box does not delay transitions and is in good working order.

Read

How to properly use tiptronic on an automatic transmission

The simplest actions that any car enthusiast can perform for his favorite iron horse when tightening is to change the oil filter and the “transmission” itself in the automatic transmission. But you need to buy consumables in trusted places so as not to stumble upon a fake.

Problems associated with friction disc wear

• Reverse gear on an automatic transmission is engaged without any complaints, and when the lever is switched to forward, the car slips in place. In addition to wear of the friction discs, breakage of the cuff or breakage of the direct clutch rings, the problem may be a stuck valve in the valve body.

• Move forward only at speed no higher than second, there is no backward movement. Disc wear affects. The problem may also be a breakage (wear) of the piston seals or breakage (wear) of the clutch oil sealing rings. If everything is in order here, pay attention to the clutch drum: the spline joint may be cut off or otherwise damaged.

• After the oil warms up, slipping is observed when moving both forward and backward. This phenomenon occurs when the viscosity of the oil decreases when heated, and the worn discs are not pressed so tightly against each other. Friction dust, a product of disc wear, may also be the cause. It clogs the filter mesh, causing the main pressure to drop.

Solutions to the problem

Based on the data in the table above, there can be many reasons for incorrect gear shifting on an automatic transmission. Methods for eliminating the problem will depend solely on the signs of a malfunction in the automatic transmission of your vehicle.

In any case, first of all, you need to check:

Level and condition of transmission fluid. The level should always be normal, the same applies to the condition. If there is little oil in the system, then the cause of its leakage must be identified and solved, and fluid added to the system. If the quality of the TM is low, that is, it contains dust from wear of the friction discs, then the discs should be replaced and the lubricant should be changed. At the same time, do not forget to flush the system several times.
Conditions of clutches. As can be understood from the table, wear of the clutches is one of the most common problems when it is impossible to change gears. Carry out diagnostics and, if necessary, replacement of clutches.
Check the functionality of the valves. If they jam for any reason, then this must be eliminated.
Check the operation of the rocker, transmission system wiring, and speed controller. It would be a good idea to check the brake band as well. If any of these elements are not working correctly, the problem should be corrected.

If none of this helps, then the only way out is computer diagnostics. Diagnostics of the unit is carried out individually in each case, taking into account all the requirements of the automobile manufacturer. We will look at this process in general. So, you will need a computer or laptop and a diagnostic cable.

The appropriate program must be installed on the computer:

The computer is connected via a diagnostic cable to a special connector (diagnostic). The location of the connector will be individual in each case. Sometimes this connector is located under the hood, but most often it can be found under the steering wheel on the driver's side. It is usually hidden behind a plastic cover, so you need to open it.
After connecting, the diagnostic utility starts on the computer. It may take several minutes for the program to synchronize with the car’s on-board computer. After that, run the diagnostics. If possible, before starting the test, select the “Gearbox” item so that only the automatic transmission is diagnosed, and not all components of the car.
Upon completion of the diagnostics, the program will give you a list of error codes that indicate certain malfunctions. You need to decipher these codes in accordance with the documentation for your car. Some of the decoding instructions can be found on our resource. Once you understand what the problem is, you can solve the problem.

1. Find the diagnostic connector in your car, usually located on the left.

2. You must connect your laptop to this connector via a cable.

3. Carry out diagnostics in accordance with the instructions and read the codes.

Recommendations for use

Forget about slipping - you need to eliminate it by any means necessary. Automatic transmissions have a negative attitude towards slipping, especially in snowy and icy conditions.
Always warm up the automatic transmission in winter. With an unheated automatic transmission, the likelihood of certain elements of the unit failing is very high.
Don't use neutral speed in vain. Mode “N” is considered a service mode, so limit its activation.
Cars with automatic transmissions should not be towed by anyone, since such transmissions are simply not designed for this. Loads have a very negative impact on the design of the unit as a whole. If you plan to drive with a trailer, then keep this factor in mind when purchasing a car.
Cars with automatic transmission are not allowed.
Do not tow your car with a rope. While driving, lubricant should always circulate in the transmission, but if the engine is turned off, the TM will not move through the system. Of course, this negatively affects the operation of the unit as a whole.
Always use only high-quality transmission fluid recommended by your vehicle manufacturer. Remember that using a cheaper lubricant over time can only harm the unit of your car, if not kill it.

Automatic transmission does not change gears: reasons

Depending on the brand and manufacturer, automatic transmissions may have some differences, but the main causes of shifting problems are common. Let's start with the fact that the most common mistake leading to automatic transmission failure is turning on the drive mode “D” without stopping when moving in reverse. The same can be said about engaging “R” when driving forward.

You need to understand that “neutral” is a mode that unlocks the wheels for the possibility of short-term towing or moving the car in the event of some kind of malfunction. For an automatic transmission, there is no need to use it during everyday use of the car, as this causes increased wear.

In what cases does the box kick?

There are many reasons why the normal operation of an automatic transmission is disrupted. Let's consider the main ones, as well as possible solutions to problems:

The automatic transmission kicks while driving. This indicates a malfunction of the valve body or torque converter. They will probably need to be replaced.
Shocks are felt in the automatic transmission during braking. A sign of a faulty clutch or valve body. Replacement of failed spare parts will be required.
The box jerks when engaging reverse gear. A broken sensor or possible problems with the torque converter. Replacement required.
The automatic transmission kicks when cold. Transmission components are worn out. Replacement of worn parts.

Let's look at some cases in more detail.