Emergency mode automatic transmission: what to do? Automatic transmission error: why the car enters emergency mode

Today I will talk about the emergency mode in which the automatic transmission gets up when it is faulty. I want to warn all car owners, whose automatic machine went into emergency mode, the car stood in the garage overnight, and you went quietly to work the next day. This is not the way out. There was the first bell - so you need to take the box for diagnosis. The machine will stand in the middle of the track - not only you, but also other road users can suffer.

What is automatic transmission emergency mode

Now let's talk about what emergency mode is. You have probably read about these cases or have already met with such situations when on the monitor dashboard the following lamps are lit, which may flash or freeze in one position:

hold;
check engine;

These lamps go out after restarting the engine or resetting the error by removing the wire from the negative terminal of the battery.

Attention! I do not recommend resetting errors by removing the wire from the battery terminal. Thus, you do not eliminate the cause, but extinguish the symptom. By the way, for us, experienced mechanics, after such a reset it is more difficult to determine the real problem.

Sometimes emergency operation may be preceded by the following symptoms:

start and move vehicle only in third gear;
jolts and jerks during gear shifting;
you can not switch the box to parking mode or reverse speed;
signal lamps are on;
vibration of the selector while idle at traffic lights.

If the automatic transmission has fallen into an “emergency gang” and does not want to leave it at all, even after resetting the error, then the malfunction lies in the automatic control unit itself. In this case, only replacing the device with a new one will help.

Write in the comments what malfunctions you encountered when your automatic transmission was faulty.

Automatic transmission solenoids

The reasons why the gearbox fails may lie in faulty solenoids. Solenoids are very sensitive to oil quality and pressure. Therefore, both experienced mechanics and I recommend paying increased attention to the original automatic transmission lubricant.

An automatic transmission is structurally significantly different from classical mechanics. Over the decades of the evolution of cars, the automatic transmission has changed a lot, the number of steps has increased (there are options for a multi-speed automatic with 7, 8 or 9 gears), and the boxes are now equipped with an electronic control unit. The device of a modern “automatic machine” has become more complicated, which overshadows the numerous advantages of a fly in the ointment in the form of a decrease in reliability, because the more complicated the design, the more troubles, including material costs, its breakdown causes.

Automatic transmission makes it easier for the driver to control, removing unnecessary obligations from him to shift gears, now these functions are carried out by the control unit. The modes of operation of the box are adapted to the driving style of the car owner, and since the process is automated, professional skills are not required. Advanced drivers practicing extreme driving, they will not exchange mechanics for anything, but the bulk of motorists choose automatic transmission. With high-quality care for the box and moderate operating conditions, the device will faithfully serve its 250,000 or up to 5 years, but under the influence of various adverse factors, the period can be significantly reduced. In case of violation of the normal operation of the automatic transmission, a transition to emergency mode is typical, most often the driver is given the opportunity to get to the nearest service. This is a common phenomenon, which does not depend on whether the device belongs to a certain type (classic automatic transmission, robotic or CVT) or manufacturer.

What is automatic transmission emergency mode

If normal work automatic transmission is not carried out, any malfunction or failure has occurred, the electronic unit control activates emergency mode. Notifications or warning lights illuminate on the vehicle's dashboard to notify the driver of this condition.

When the automatic transmission enters emergency mode, the car is characterized by a loss of dynamics, a slow set of speeds and movement only in third gear, and it becomes difficult to start the engine, especially at sub-zero temperatures overboard. In most cases, the car is able to go to the service station under its own power, continue moving up to 60 km / h, but in case of serious malfunctions, it is better not to risk it and call a specialist directly to the place or park and use the services of a tow truck.

It is impossible to operate the car in the emergency mode of the automatic transmission. Such actions can lead to even more serious malfunctions, threatening an expensive repair of the “automatic” box. All that transport can be used for under such circumstances is movement towards the service to repair the breakdown.

When you turn on the emergency mode, you should identify the reason for its activation and take measures to eliminate the problem. If the automatic transmission not only signals the transition to this mode, but also makes various noises in addition, it is risky to drive on your own, since the consequences for the device, as well as the car owner’s pocket, can be sad.

Possible causes and solutions

Let's consider why this trouble occurs and how to get out of the emergency mode of the automatic transmission, when the problem can be fixed on its own.

The ECU, like other electronics, is capable of simply giving an error. Then the problem is solved simply by analogy with a computer that, after a reboot, starts working correctly - stop and restart power unit save the day in some cases. Sometimes a battery reset can help. But if simple methods of solving the problem have not been effective, it's time to diagnose.

There can be several reasons why the automatic transmission goes into emergency mode, the main ones are:

the ATF fluid level has deviated from normal values;
malfunctions of hydraulics or the mechanical component of the box;
incorrect functioning of the electronic control unit.

Fluid level deviations in any direction can provoke malfunctions in the operation of the device, as a result of which the automatic transmission goes into emergency mode, the control unit in these circumstances acts as a protective mechanism, protecting against the consequences of underfilling or overfilling.

With an excess volume of liquid, the excess will simply need to be removed, and then the ECU error should be reset, and if there is not enough, the cause of this phenomenon should be found and eliminated. A critically low level of lubrication, as well as an excessively high level, are dangerous for the device, so you can’t hesitate here. The result of exceeding the required amount of ATF is foaming, an insufficient amount leads to a decrease in oil pressure in the valve body, oil starvation, which in turn provokes a number of problems, since the parts of the box are not lubricated and wear out quickly from friction, and their fragments damage other elements. A decrease in the level of lubrication leads to a decrease in pressure in the valve body, which entails related malfunctions. Reasons why fluid is not enough:

underfilling during automatic transmission maintenance. The ATF level is checked with a dipstick, if a lack of volume is detected, the liquid is added. It is important to use the same lubricant that was already filled in the box, otherwise performance will deteriorate as a result of additive conflicts. When a critical level of liquid is detected, we are already talking about a leak;
violation of the integrity of the automatic transmission housing. Then - a meaningless exercise, it will still leave, and the emergency mode will become a regular-periodic phenomenon for the automatic transmission. It all depends on the severity of the damage. Repair work they will cost a lot, and sometimes they will be impractical, since their cost may approach the price of a new box;
seal wear. You can solve the problem of the occurrence of an emergency mode under such circumstances on your own, simply by replacing the worn element;
wear of the gasket between the engine and gearbox. It is possible to resolve the issue only by replacing the element, and the device is not separately removed on all brands of cars, so it is better to call in a service where the procedure will be performed using the necessary equipment.

Unsuitable is also one of the provocateurs of the incorrect operation of the box and its transition to emergency mode, so you should carefully monitor the materials used when servicing the device.

Malfunctions of hydraulics or mechanical part of the box

The automatic transmission may signal a malfunction due to violations of the integrity of the housing, wear of the friction group, which is not uncommon, problems with the valve body. Electronic diagnostics do not always give a clear picture of what is happening, because in order to accurately find out the source of the trouble, you will have to remove the pan to inspect for dirt, signs of wear - metal chips, friction dust, etc. It happens that you need to completely dismantle and disassemble the box to accurately assess the condition of the transmission elements .

Clutch wear quickly renders the transmission fluid unusable. Damaged gear teeth and wear products of parts according to the domino principle disable the rest of the automatic transmission, which over time will lead to overhaul devices.

Incorrect operation of the electronic control system

Often, emergency mode is provoked by a breakdown of the computer, sensors, connecting cables or contacts. Each of the possible sources of the problem requires separate consideration:

if the automatic transmission runs on a regular basis or falls into it after warming up to operating temperature, the temperature sensor may be malfunctioning. It must be replaced if a problem is identified;
when shifting gear into "D" mode, a thud can be heard, followed by activation of the emergency mode. It is also possible to turn it on when shifting from first to second gear. Then the reason lies in the breakdown of the rotation sensors of the input or output shaft. A malfunction is diagnosed by scanning, and eliminated by replacing parts;
camshaft sensor problems throttle valve, air leads to a stable presence of the box in emergency mode or its unexpected inclusion, but not when shifting gears. The problem is determined by scanning and is solved by replacing the desired element;
poor contact of the loops, among other things, can also provoke jolts, jerks, slips and other noticeable malfunctions. In this case, the transition to an accident is unstable and can manifest itself at any time. If the diagnostics did not reveal the sources of the problem, we solve the issue by calling or trial replacement of elements;
often the forerunner of automatic transmission emergency mode is damaged or contaminated channels of the valve body, malfunctions of solenoids, scoring in the valve plate, jamming of plungers. Such problems are caused by low-quality lubricant, as well as its untimely replacement;
when the automatic transmission does not come out of the accident with all the attempts made to correct the situation, the problem is probably in the failure of the control unit. Diagnosing such a problem is difficult, but a trial replacement of the ECU will clarify the situation.

What to do if the automatic transmission is in emergency mode

Respond to box signals immediately, as the problem will not be resolved by itself, and the continuation of the trip may end in an undesirable way.

First of all, you need to stop and turn off the engine, then start it again, and then continue the trip in moderate mode and, if the error repeats, resolve the issue in other ways.

Further actions, if the problem is not solved, are to measure the ATF fluid level and check its condition, after which it is necessary to act on the situation, correcting it, depending on what deviations were found.

If previous attempts were unsuccessful and the automatic transmission again falls into emergency mode, you should immediately go to the service to diagnose and fix the problem, since self-diagnosis does not always determine the cause of the malfunction.

To begin with, today there are several types of automatic transmissions:, and. At the same time, various malfunctions are characteristic of each type of gearbox, and quite often and regardless of the type of gearbox, the machine “gets up” in emergency mode.

In this article, we will consider a classic automatic transmission with (hydromechanical automatic transmission), what is an emergency mode for an automatic machine of this type, and also why the automatic transmission goes into an “accident”.

Read in this article

Automatic transmission emergency mode: what is it

So, the transition of the gearbox to emergency mode occurs if there is a breakdown or malfunction of the unit. In other words, the activation of the emergency mode on the machine signals the occurrence of certain problems.

At the same time, notifications or warning lights for check AT, HOLD, check engine, etc. light up on the instrument panel. If the automatic transmission "got" into an accident, the car stops accelerating dynamically, the sharp response to pressing the gas pedal disappears, gears do not change in D mode, etc. The fact is that in this mode the car starts and moves only in third gear.

At the same time, the emergency mode itself can be considered protective, since its inclusion allows you to prevent a number of more serious damage to the automatic transmission. More emergency mode automatic box transmission retains the ability to continue moving under its own power to the nearest service station.

In other words, you can’t constantly drive in automatic transmission emergency mode, but you can get to a car service without a tow truck. Now let's look at why and when the emergency mode of the automatic transmission is activated, the reasons for its activation, as well as options and ways to solve the problem.

Automatic transmission goes into emergency mode: reasons

Let's start with the fact that modern automatic transmissions are quite complex units. At the same time, as practice shows, there are several main reasons why the automatic transmission “falls” into an accident.

First of all, a low or high ATF level in the box can lead to malfunctions, as a result of which the emergency mode is activated at the command of the automatic transmission ECU.

Underleveling can occur as a result of leaks, while overleveling is often due to errors during box maintenance. For example, overflowing fluid into an automatic transmission leads to foaming, and a shortage leads to oil starvation.

The result is a decrease in pressure and deterioration of lubrication, rubbing surfaces at the points of contact wear out heavily. Electronics fixes deviations from the norm, emergency mode is activated, an error is registered in the ECU by the box.

For this reason, if the box went into emergency mode, you need. It is also recommended to carry out automatic transmission self-diagnosis (if possible and if you have the skills to carry out this operation).

Another reason may be malfunctions associated with the operation of hydraulic devices, as well as problems in terms of mechanics. For example, the emergency mode of the automatic transmission may turn on if the body of the automatic transmission is damaged, slip, worn, skidding or “burnt”, there are problems with the gas turbine engine, etc.

In this case, it is necessary to carry out an in-depth diagnosis of the automatic transmission. Check starts with computer diagnostics, however, such a scan does not always provide a clear idea of the nature and cause of the malfunction.

In this case, it may be necessary to dismantle the gearbox pan in order to inspect for contamination, friction dust, metal chips. In some cases, for troubleshooting, it will also be necessary to completely remove the automatic transmission and disassemble the unit in order to assess the degree of wear and condition of individual elements.

The third reason for the transition of the machine to emergency mode is problems with the automatic transmission electronic control system. In this case, the symptoms may be different, the malfunction may be "floating" or persist permanently.

For example, it works fine on a cold box, but after warming up, the automatic transmission immediately goes into emergency mode. In such a situation, the culprit is often the temperature sensor, which needs to be replaced.

If the gearbox "falls" into emergency mode unexpectedly, that is, regardless of various factors and conditions, then the cause may be a banal damage to the wiring, problems with contacts, etc. In this case, an experienced diagnostician checks the wiring and connections.

In addition, if the transmission suddenly goes into emergency mode, and this transition does not occur during a gear shift, then the sensors may be the cause (sensor camshaft, etc.). In this case, you need a complex.

Also, often problems with automatic transmission occur when the driver moves the selector to position D or at the moment of switching from 1st to 2nd gear. At this time, a blow is heard in the box, then the emergency mode of the automatic transmission is activated. In this situation, the probability of damage to the shaft rotation sensors is high.

It should be remembered that the contacts of the sensors can oxidize or break, thin wiring often breaks, cables wear out, etc. As a result, the connection is lost. This is also one of the answers to the question why the automatic transmission went into emergency mode.

For automatic transmission diagnostics in emergency mode, it is better to read errors using a diagnostic scanner, since automatic transmission self-diagnosis is not always able to detect a problem. If the diagnostics do not give results, then the breakdown should be looked for manually (by checking the sensors, “ringing” the circuits, etc.).

If the automatic transmission is in emergency mode all the time, while restarting the engine or resetting errors does not help, and the sensors and wiring are in order, then the possibility of problems with the gearbox ECU should not be ruled out. In this case, they often resort to the method of replacing the block with a known working one in order to check.

A common cause of automatic transmission failure is contamination / damage to the channels, the appearance of scoring in the valve plate, malfunctioning solenoids. In this case, the machine operates in emergency mode. The reason is increased sensitivity to the quality of the oil in the automatic transmission and fluid pressure.

To avoid such a breakdown, it is necessary in a timely manner. You also need to use only such ATF fluid that the manufacturer allows for use in a particular type of automatic transmission.

Remember, mixing transmission fluid from different manufacturers can cause the additive packages to react, as a result of which the properties of the oil will change and the automatic transmission will malfunction.

It turns out that if the automatic transmission has switched to emergency mode, the oil level is normal, but its color, smell, viscosity and general condition are in doubt, then you should diagnose the box and be prepared, at least

What is the result

As you can see, there are a lot of reasons why the emergency mode of the automatic transmission is turned on. At the same time, even rare inclusions of this mode, which are eliminated by restarting the internal combustion engine, indicate that there is already a problem with the machine and with a high degree of probability it will only progress.

As for the errors and failures themselves, a long drive in a car in which the box has switched to emergency mode is not allowed. In other words, in this mode, you can only get to the car service, while avoiding loads on the automatic transmission.

Let us remind you once again that until the breakdown or malfunction is eliminated, the regular operation of a car with an automatic gearbox in emergency mode is prohibited! Moreover, if the automatic transmission has already “gone” into an accident, but when driving, you can hear extraneous sounds during the operation of the machine (grinding, hum, crunch, bumps), then it is better to refuse to drive to the service on your own.

The best rhenium in such a situation would be to call a tow truck, since towing a car with a faulty machine gun without hanging the drive wheels can lead to even more serious consequences for the automatic transmission, which is already faulty in itself and has switched to “emergency” mode.

What to do if the machine goes into an accident?

In the event of a malfunction of the valve body solenoids, wiring problems, a short movement should not turn into sad consequences, since the automatic transmission ECU selects the safest mode of operation. The concept of emergency mode means that the car moves only at one of the speeds. If the automatic transmission got into an accident and blocked the second or third gear, follow the following algorithm of actions:

stop and check the oil level in the automatic transmission. If the transmission design does not include a dipstick, look under the vehicle. flowing transmission fluid red, the characteristic smell of burnt oil indicates that it is not worth going further;
move the wiring harnesses going to the automatic transmission. If the reason is poor contact of the engine compartment wiring, with the proper set of circumstances, you will be able to temporarily remove the box from emergency mode;
turn off the engine, turn off the ignition for 1-2 minutes. If it does not help, disconnect the negative battery terminal for 2-3 minutes. On some cars, such manipulations really allow you to remove the emergency mode;
if the oil level is correct, continue driving to a safe stop or the nearest service station. At the same time, you need to drive as carefully as possible. Do not press the pedal to the floor, driving the engine speed into the red zone.

Possible causes of malfunction

Going beyond the operating temperature, in other words - overheating.
Insufficient ATF fluid level, resulting in a decrease in oil pressure in the valve body. Often, a breakdown does not occur at lightning speed and begins to manifest itself with a belated shifting of gears, shocks, shocks when switching.
Fault . For an accurate selection of the moment of gear shifting, effective acceleration and fuel economy, the automatic transmission electronic control unit is based on the readings of either DBP, TPS. Incorrect operation of the sensors ignites the Check Engine on the dashboard, but can also cause jolts, bumps and the automatic transmission to go into emergency mode.

Where should you start diagnosing?

Only the earliest models did without an electronic component. All other units, depending on the model and year of manufacture of the automatic transmission, have an electronic "brain" and a self-diagnosis system. If the automatic transmission on your car got into an “accident”, you should start with computer diagnostics. You will need a device to connect to the diagnostic socket and the appropriate software for reading information. After reading the current fault codes, look for their decryption on the Internet in order to more clearly represent the direction of further searches. The most common causes of automatic transmission emergency mode:

wrong gear ratio individual transfers;
malfunctions in the electrical circuit of the solenoid valves;
discrepancy between the speed of the input and output shaft of the gearbox.

In case of an error on the solenoid valves, do not rush to disassemble the automatic transmission. It is necessary to diagnose the wiring and the computer of the automatic transmission. If you know, then easily check the resistance of the wires, the shaft rotation sensor. You need to remove the connectors from the box body, as well as the automatic transmission control unit connector. Check the wires not only for an open, a short to “-”, “+”, but also for a short to each other. This is quite likely in the case of grinding or melting of the insulation. Also, be sure to check whether power is “coming” to the connector of the control unit and whether there is a reliable “ground”. The location of the control units, the pinout of the connectors and the colors of the wires can be found in the manual for the repair and operation of the car.

The video by Ivan Saichenko shows how to properly check the wiring if the automatic transmission is in emergency mode.

Visual inspection and soldering of contacts

When looking for the cause of the emergency mode of an automatic transmission, pay attention not only to the wiring harnesses in places where they come into contact with the body, but also to the power connectors themselves. Sometimes, due to corrosion, inaccurate removal / installation, the pins of the connectors simply break off. Automatic transmission can go into emergency mode even in the presence of oxides on the contacts.

On many Audi, Mercedes, the automatic control unit is located under the front seat, where moisture often gets in. Before disassembling the automatic transmission, it will be useful to pull out the control unit board. Even if there are no oxides on it, we recommend that you make sure that there are no microcracks in the soldering points, and, if necessary, solder the main contacts.

We recommend disassembling the box for troubleshooting the hydraulic unit, checking solenoids, clutch packs only after complete diagnosis electrical circuits and easily accessible elements.

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