What is the button on the automatic transmission o d. Automatic transmission overdrive - what it is and how to use it. Should you deactivate the overdrive mode in the city?

Many drivers, changing from mechanics to "automatic", cannot immediately figure out what is needed Overdrive button on automatic transmission and whether it is worth pressing it at all.

This article will help you understand the principle of operation of this mode, tell you in what cases and how the button can be useful to the driver, and in which overdrive will only lead to rapid wear of the automatic transmission components. So, first things first.

On classic automatic gearboxes, in most cases, a 3-4-speed gear ratio system is used.

In this case, the second or third stage is direct, i.e. her ratio is equal to one. The third-fourth gear of the classic "automatic" has a gear ratio of less than one and is called overdrive (O / D).

Recall the automatic transmission modes:

"P" (Parking) Parking mode;
"N" (Neutral). Neutralka;
"R" (Reverse). Reverse gear;
"D" (Drive). Forward movement;
"D3" or "O / D OFF" - only 1st, 2nd and 3rd gears;
"2" or "S" - 1st, 2nd gear, or only 2nd item "Winter mode";
"1" or "L" only 1st gear "Sport" or "Power" switching only at high revs;
"Kickdown" all the way to the gas pedal;
"NORM" - Economy. Switch. at medium speeds;
"PWR" at max. revolutions;
"SNOW" - get under way from the 2nd gear;
"Manual mode" "+" "-".

Overdrive is an increasing stage, that is, when the O / D mode is on, the secondary shaft rotates faster than the primary.

Typically, the automatic transmission goes into overdrive at speeds over 50 kilometers per hour, as soon as the driver releases the accelerator pedal. It is generally accepted that the 4th-5th speed saves fuel and protects the engine from premature wear.

When the O / D mode is off, the box will not switch to a higher stage under any circumstances. The driver can forcibly enable or disable the "overdrive" mode, for this there is a corresponding button labeled "O / D on / off".

To find out that the overdrive mode is currently deactivated helps the light indication - on dashboard the yellow inscription O / D off lights up (the activated overdrive has no light indication). Logically, this means that overdrive should be enabled by default.

It is recommended to move the overdrive button to the "O / D off" position under the following maneuvers and circumstances:

When overtaking at high speed, when a large and sharp acceleration is required. Immediately after the overtaking maneuver, the automatic transmission manufacturers recommend returning to the overdrive mode again;
When driving off-road / snow at low speed;
While towing another vehicle or while driving with a heavy trailer;
On a long rise;
When driving at speeds up to 60 kilometers per hour;
When driving in difficult road conditions that require constant speed reduction / acceleration.

Should you deactivate overdrive mode in the city?

There are two diametrically opposed beliefs on this controversial issue, and each of their adherents has their own arguments.

The former believe that overdrive is not needed in the city, since it is impossible to move at a constant speed for a long time, unlike driving on the highway. To prevent the machine from making a large number of changes, the overdrive mode is turned off, considering that this will also reduce the wear of automatic transmission components and assemblies and save gasoline.

Another part of automatic car owners believe that it is not necessary to turn off the mode that increases the gear ratio of the box.

Their logic is as follows: in the city cycle, the automatic transmission switches more often than on the highway, in any case - whether overdrive is on or not.

As for fuel consumption, then the opinion is as follows: since with the same driving style in the city, the consumption is higher than on the highway, then driving in an overdrive gear will at least slightly, but will reduce fuel consumption.

There is no definite answer to the question of the advisability of the overdrive function in the city.

It all depends on a number of circumstances:

engine acceleration;
the experience and driving style of the driver;
specific driving conditions, etc.

Disable overdrive for convenience and fuel economy should definitely be done when descending a long ridge or serpentine.

In this case, it will not be necessary to brake the car at all by pressing the brake pedal, since engine braking will be triggered. At such moments, the supply of fuel to the cylinders is minimal.

Why doesn't the Overdrive button work?

Overdrive button not working maybe for a number of reasons. Like any other mechanism in a car, the overdrive button on the automatic transmission has its own resource, and can fail during intensive use, simply due to physical wear and tear (which is extremely rare in practice).

The most common cause of an O / D button failure is a broken wire or poor contact on the connector going to the button. In this case, you can fix the problem by disassembling the automatic transmission shift knob and restoring the integrity of the wiring.

If everything is in order with the button itself, the wires and connectors are intact, then the problem can be much more serious. In particular, you should check the overdrive sensor and diagnose the automatic transmission itself.

Or how fuel filter killed injectors Jeep Grand Cherokee WK2 (2012)

Diesel Jeep Grand Cherokee is good for everyone. Handsome. Reliable. And it can serve faithfully for a long time to its owner. Provided that the owner will serve his iron horse and feed him quality fuel, oils and consumables. How violation of the scheduled deadlines can lead to the replacement of injectors, read below.

Automobile: Jeep grand Cherokee
Year of issue: 2012
Engine: EXF (3.0L, 2987cc, 247hp)
Internal combustion engine features: V6, diesel
Gearbox: NAG1 (DGJ, automatic, 5 steps, AWD)
Mileage: 119,819 kilometers
Reason for contact: Lit " Check Engine», Difficult starting of the engine.

Nozzles and fuel injection pump Grand Cherokee.

The car in question was serviced in a large network multi-brand technical center before coming to us. According to the owner, he did it regularly, as recommended in the instructions. He turned to us because the engine starts well, but it takes a very long time. The starter turns, but the car does not start for several minutes. When asked how long ago the fuel filters had changed, the owner of the car was very surprised. The fact is that in the previous service he was assured that on this car there is no fuel filter. Well, apparently they confused it with the gasoline version. On Jeep Grand Cherokee gasoline engines, the fuel system layout eliminates the in-line fuel filter. Diesel Grand has as many as two in-line filters, one of which could not withstand more than 100 thousand mileage without replacement, and began to collapse. It should be noted that the filter was made of corrugated filter paper, in contrast to the fibrous material used in original filters and high-quality analogs. How he got there and when, now it is impossible to find out.

The particles of the filter element, feeling a sudden freedom, rushed with all their might fuel system through the injection pump and the fuel pressure regulator directly to the injectors, igniting on the way the error P0088-00 Fuel rail pressure too high and Check Engine on the dashboard. One replacement of fuel filters is now definitely not enough. Having removed the fuel supply control valve from the injection pump, aka Fuel Quantity Solenoid (FQS), they were not at all surprised to see a large amount of foreign impurities under it.

Filter particles in the injection pump Grand Cherokee 3.0 CRD

The results of tests and checks described in the article about the P0088 error revealed that it is necessary to check the injectors and the fuel pump high pressure(Injection pump) at the stand. We arm ourselves with special tools and proceed to dismantling. No special key for fuel pipes there is a chance of damage to the electrical part of the injectors, or adjacent parts.

Without such a key, replacing the injectors is difficult.

The automatic transmission is no longer a luxury, but a common feature of a large number of cars. New way switching requires other skills and abilities from the driver. Not everyone knows about such a checkpoint function as overdrive (o / d). Indeed, the developers of the modern transmission left the drivers a lot of reasons for thought. Today you will learn everything about automatic transmission overdrive - what it is and how to use it.

What is the O / D button on an automatic transmission?

An overdrive is called a special one, which must be turned on when driving on highways and other roads, where all the conditions for high speed are created. At its core, overdrive is analogous to the fifth gear, which is in the manual transmission. The principle of operation of this function is that when this mode is turned on, the box switches from 1st to 4th gear sequentially, and when turned off, 4th gear is blocked and the car moves in 3rd gear at maximum revs.

To understand what overdrive is for, you need to analyze the following example. Suppose the car is moving downhill in heavy traffic Vehicle where the speed range varies from 40 to 60 km / h. In this case, the O / D mode is on. When the speed drops to 40 km / h, the box does not switch from 4th to 3rd, the speed drops, and the flow rate begins to increase. Starting acceleration, it is very difficult for the car to quickly gain the required revs; moreover, the gearbox starts to work in a mode of too high loads, which leads to its accelerated wear. To switch to 3rd, it is necessary to sharply depress the gas pedal or reduce the speed by pressing the brake pedal, and this will make the car behave inadequately and the shock loads on the automatic transmission will only increase.

If you turn off the overdrive mode, 4th gear is blocked and the car moves only in 3rd gear. That is, there will be no switching, the car will briskly accelerate from 40 to 60 km / h, and with a decrease in speed, it will have the required revs.

At first glance, it would seem that in this case there is a big difference in fuel consumption. After all, if you drive too long at high speeds, then fuel consumption increases. There is a certain grain of truth in this. But do not forget that at low revs when driving in top gear, fuel consumption also increases due to the fact that the engine efficiency drops sharply. Therefore, if there is a difference in fuel consumption, it is only the smallest. Naturally, when driving on the highway, overdrive should be turned on, as this will already be real fuel economy.

The overdrive is switched on using a special button on the handle for switching the automatic transmission operating modes. When the O / D is off, a special warning lamp with the inscription "O / D off" lights up on the instrument panel, and when it is turned on, the inscription disappears, and when switching to 4th gear, there is a slight jolt, which means that the overdrive is on. Turnover, while falling a little. Many drivers mistakenly assume that this push means the inclusion of 5th gear, although in fact, this is accompanied by an elementary blockage of the hydraulic transformer.

Video - Automatic transmission operating modes

How to use overdrive on an automatic transmission?

To date, there is no clear explanation of how to use this function. This is due to a big difference traffic situations and engine power for different cars... Drivers enable and disable this feature based on years of experience, but what should beginners do?

This question can be answered by experts who give the following recommendations on this matter. Here are the following cases when you need to disable O / D:

When driving on long slopes or inclines... It is perfectly clear why this should be done on the ascent, but why is the overdrive turned off on the descent? When an overdrive is engaged, the car is coasting better, which means that the braking efficiency is reduced, which has a great impact on driving safety. That is why, on descents, overdrive must be turned off.
When driving in heavy traffic where the speed of movement changes periodically.
When overtaking at a speed not exceeding 90 km / h... Although the overtaking opinion is controversial. On the one hand, the increase in revs contributes to the quick completion of the maneuver, and on the other hand, it is no longer safe to take your hand off the steering wheel to press the button, although the overdrive can be turned off by abruptly pressing the gas pedal all the way. In addition, if you do not know your car, then you can bring the engine speed to the red zone while reducing the gear, which will accelerate its wear. Everything will depend on the experience of driving this car.

The question of the use of this function in the city is also controversial. It all depends on the throttle response of the engine and the specific driving conditions. Therefore, there is still no clear explanation on this matter.

Where should overdrive be applied? When driving on the highway, as well as in any places where a sufficiently high speed of movement is allowed.

Position "P"

It is selected when the car is parked for a long time. In this position of the range selection lever in the box, all controls are turned off, and its output shaft is blocked; vehicle movement is impossible. It is only permissible to move the lever to this position when it comes to a complete stop. Moving the lever to the "P" position while driving will damage the transmission.

Position "R"

Reverse. Move the range selector lever to this position only when the vehicle is stationary. Moving the lever to the "R" position while driving forward may damage the gearbox and other transmission components.

Position "N"

Corresponds to neutral. In the gearbox, either all controls are turned off, or only one is turned on, which ensures that there is no rigid kinematic connection between its driving and driven shafts. In this case, the output shaft locking mechanism is turned off, i.e. the car can move freely.

Position "D", "D4"

Basic driving mode. It provides automatic switching c, first to fourth (sometimes third - in three-speed automatic transmissions) gear. It is recommended to use it in normal driving conditions.

OD button

On some car models, permission to use the fourth (on some cars - the fifth), overdrive, is carried out using a special button "OD". If it is in the recessed position and the range selector lever is in the "D" position, then upshifting is permitted. Otherwise, the inclusion of the fourth overdrive is prohibited. In this case, the state of the control system is indicated by the indicator "O / D OFF". When the overdrive is enabled, the indicator is off, and when disabled, it lights up. This mode is used when driving on express roads... If possible, do not use this mode in the city, especially in winter - this excludes the overdrive from the operation and allows more efficient use of the engine braking mode. Do not enter O / D mode when the vehicle is fully loaded. If there are frequent shifts from 3rd to 4th gear and vice versa, to prevent increased wear of the automatic transmission parts, turn off the O / D mode.

Usually the "O / D" button is located on the range selector lever. On some models, the "O / D" button is located either on the dashboard or near the range lever.

For vehicles equipped with four-speed gearboxes, the range lever generally has three further forward positions: "3", "2" and "1". In some cars, the "1" range is indicated by the Latin letter "L".

Position "3" or "D3"

Driving in the first three gears is allowed. Recommended for use when driving on a hilly road or in conditions of frequent stops (city driving).

Position "2"

Driving is allowed only in first and second gears. Recommended for use, for example, on winding mountain roads. Shifting to third and fourth gears is prohibited. Engine braking is effectively used in this range.

Position "1" or "L"

Driving is allowed only in first gear. This range allows the maximum implementation of the engine braking mode. It is recommended when driving on steep descents, ascents and off-road conditions.

On some vehicles (eg Volvo 940) the "L" position is the same as "2".

Be careful not to accidentally set the lever to the "L" position when driving at high speed. Sudden engine braking can lead to skidding.

Manufacturers make given type transmission in such a way as to achieve maximum user convenience and versatility. At the same time, the task is also to reduce fuel consumption.

As you know, the most common today is a simple four-speed automatic. As a rule, these transmissions have several standard and understandable modes of operation, which greatly simplifies operation.

However, on many automatic transmissions, in addition to the basic ones, you can also find additional modes. In this article we will talk about what overdrive is on an automatic transmission, how overdrive is turned on and off on an automatic transmission, why such a mode is needed and when it is used.

Read in this article

What is an automatic transmission overdrive for?

If we consider the device of an automatic transmission with 4 gears (steps, speeds), in this case, 3rd gear is direct, that is, it has a gear ratio of 1, which is similar to 4th gear.

In this case, 4th gear in automatic box also called overdrive or O / D. By analogy with mechanics, the gear ratio of this gear is less than 1, that is, the gear is overdrive, like the 5th gear in the manual transmission.

As you know, the overdrive on the mechanics is included at speeds of 80 or even 100 km / h. This transmission allows you to significantly save fuel when driving on the highway at high speed. In the case of an automatic transmission, where the driver cannot change gears on his own, the O / D (overdrive) mode is separately switched on and off using a separate button.

The overdrive button can be located on the automatic transmission selector or taken out separately. So, if the overdrive automatic transmission is turned on, this means that the automatic transmission will switch to 4th (higher) gear at high speeds, and also if the driver slightly presses the gas pedal. After engaging the 4th gear, the blocking is activated.

In practice, switching to the 4th occurs already at a speed of about 45-50 km / h. It is quite obvious that 4th gear saves fuel when driving on the highway, and also does not allow the engine to spin up too much. high revs.

However, many car owners have a question of what to do if the car is operated within the city. In other words, whether it is necessary to turn on O \ D in the city or turn off overdrive. Let's figure it out.

Overdrive mode on automatic transmission: how to use

So, if we consider all the arguments "for" and "against", we can highlight the following:

If the overdrive mode is on, 4th gear is included as early as possible, that is, fuel is saved;
The engine runs less in high speed mode, it remains;
In the operating instructions for various brands auto, it is separately indicated that in difficult conditions the O / D mode must be turned off. At the same time, city driving with frequent stops and accelerations, overtaking and rearrangements may well be considered difficult conditions.
Also, in O / D mode, the automatic transmission often switches to 4th gear, thereby increasing the wear of the gearbox mechanisms. In parallel with the included overdrive is poorly expressed.

It becomes clear that when driving on a highway at a constant high speed, an overdrive (overdrive) must be switched on, since in this case the engine and gearbox operate in optimal mode, maximum fuel efficiency is achieved, etc.

If you turn off the overdrive, the possibility of shifting to a gear higher than 3 is blocked. Also, shifting to higher gears after the start occurs at increased engine speeds, when braking, the box "holds" the engaged gear longer, that is, downshifting occurs only when certain engine speed and speed are reached. movement.

By the way, you need to turn off O / D when overtaking for a long time at high speed (more than 100 km / h). At the same time, a short-term disengagement of the overdrive also allows you to kick-down, that is, when the driver sharply and strongly presses the gas pedal.

Also, overdrive should be turned off when towing a trailer, when driving on snow, ice, off-road, etc. Overdrive also needs to be turned off if, in connection with road conditions, you need to get the effect of engine braking.

In practice, if we talk about daily operation within the city, it is better to turn off the overdrive on the automatic transmission. This can be done with a button, which is located separately or on the gearshift lever. At the same time, O / D off lights up on the dashboard, which means the 4th gear is turned off. If overdrive is on, nothing is lit on the dashboard.

Using the O / D automatic transmission in practice

To understand how to use the overdrive mode in the city, let's look at a specific example. The car can move uphill in the stream, constantly changing the speed from 30 to 70 km / h.

If the overdrive mode is on, the automatic transmission will shift into all gears (1,2,3,4). Also after acceleration to 40-50 km. The torque converter will lock if the driver does not press the accelerator pedal hard.

Imagine that the car accelerates to 60 km / h, with the 4th gear engaged and the engine speed is low. If at a certain moment it is necessary to accelerate, one should not expect a sharp response to pressing the gas pedal, since the fourth gear is engaged, and the revolutions for intensive picking up in this gear are not enough.

It remains only to press the gas harder, kick-down will work, there will be a sharp downshift and acceleration will begin. Further, a similar situation is repeated many times over. Naturally, in this case, the comfort is significantly reduced, and the gearbox itself, with constant gear changes, wears out faster and more intensively.

If you turn off the overdrive, under load the car will move in a maximum of 3 gears, and it reacts more responsively to pressing the gas pedal, the engine speed is higher, without switching "down" there is enough traction for acceleration.

At the same time, one should not assume that disabling 4th gear will lead to an increase in fuel consumption. The fact is that the forced use of the kick-down mode in the event that O / D is turned on, ultimately, in urban operation, leads to greater fuel consumption.

It turns out that you need to be able to use the overdrive mode, turning it on and off depending on certain conditions. As mentioned above, it is better to turn off overdrive:

if active driving at low speeds is practiced;
on long descents / ascents;
if the pace of movement is constantly changing;
for comfortable movement at speeds up to 50 km / h;
when towing a trailer / transporting goods in a car;
when overtaking for a long time at medium speed;

By the way, with regard to the last point, it must be remembered that turning off the overdrive will lead to a sharp increase in engine speed, and the increase can be up to the "cutoff".

Also, you have to turn on / off the O / D mode with a separate button, while it is extremely unsafe to be distracted from the road at speed, and even more so during overtaking. For this reason, when overtaking on the track, it is optimal to use kick-down rather than overdrive.

The only exception can be considered safe overtaking relatively slow moving vehicles. In this case, the overdrive is disabled in advance, only then overtaking begins, if necessary, the kick-down is also activated in parallel with the disabled overdrive.

Finally, we note that regardless of the type of transmission and the available modes of its operation, the main thing is to be able to correctly predict the situation, take into account road conditions, features of the automatic transmission on a particular car model. Only after making sure of complete safety, it is possible to overtake, change lane and other maneuvers.