HOW TO MAKE A DIAGNOSIS OF AUTOMATIC TRANSMISSION WITH YOUR OWN HANDS

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You can assess the state of the "machine" in different ways, from external contemplation to complete disassembly of the automatic transmission. Accordingly, the price tags of car services for its diagnostics differ, and in many cases such a service is even provided free of charge.

And yet, some motorists, who want to either save money, or prove that "they are not worse than many", undertake to check this unit on their own. Is there a reason for such an initiative - further in the review.

The main stages of automatic transmission diagnostics

In an amicable way, before examining an automatic transmission, it is advisable to collect some information about it. Often, these or those automatic transmission models have already identified "weak links" that require special attention.

Before you start disassembling the box, you must inspect it from the outside. Malfunctions such as jolts and slippage can be the result of a lack of oil or a decrease in pressure in the lubrication system, caused by leaks in places:

connections between the gearbox and the motor;
contact of the box with the oil sump;
factory of the wiring cable in the automatic transmission.

If during the next stage - ringing the electronics - no problems were identified, then you can proceed to the removal and complete disassembly of the automatic transmission, which will allow diagnosing the valve body, clutches and transformer. A car enthusiast who does not have the skill sufficient to perform such work should be entrusted to a car service specialist.

The reason for the diagnosis of automatic transmission is usually the following cases:

the malfunction indicator on the control panel lights up;
the occurrence of malfunctions in the operation of the box;
purchase of a used car;
planned maintenance of the machine.

Computer diagnostics of the "machine"

Let's say the owner of a car with automatic transmission noticed that the transition from 3 to 1 gear is accompanied by some jolts, which are not observed during acceleration. A visit with such a problem to a car service can lead to the following scenarios:

The specialists check the level and quality of the oil, which showed no deviations. Verdict: “This is a feature of this type of box. Humble yourself. "

The oil is changed, the valve body is washed, the solenoids are cleaned. The transmission began to run smoother and smoother, but the jolts when downshifting did not go anywhere.

Computer diagnostics of automatic transmission is carried out. The autoscanner detects that its software is outdated, and the box itself needs to be configured. Re-flashing the unit fixes the shock problem.

And the point here is not so much about choosing a car service, although this is important, but about the importance of comprehensive diagnostics of both automatic transmissions and the car as a whole. Special equipment makes it possible to carry out such a check quickly and efficiently.

The electronics that are installed on modern cars, during their operation, constantly monitor the state of the vehicle systems. The slightest problem is recorded in the form of an error code, which can then be downloaded and decompiled. Critical malfunctions are reported to the driver by the "Check engine" indicator on the control panel.

The examination of an automatic transmission operating under the guidance of an electronic control unit should begin with computer diagnostics. Many cars allow to carry out a full-fledged check of their "automatic machines" exclusively with exclusive scanners designed for this car brand.

Such devices are usually "aware" of the permissible values of the parameters read by the sensors. Real-time comparison of control and received data allows to identify box faults with great accuracy.

But, as a rule, unofficial car services, at best, can offer to diagnose automatic transmission with a universal scanner. For motorists, it is quite expensive to purchase an original device for independent research of boxes.

Adapter instead of scanner

However, you can diagnose the box "in the garage" using a special cable for connecting to the OBD II connector and software that can scan the electronic engine and automatic transmission control units. For example, to check the "machine" on models produced by the VAG-Group, the VAG-COM KKL adapter together with the corresponding software is suitable.

Deciphering the received fault codes should not cause any particular difficulties. If a search query for a specific car did not bring any results, you can try to "punch" the automatic transmission model. It often happens that cars produced by completely different manufacturers are equipped with the same gearboxes.

Diagnostics of electrical wiring

A significant drawback of the computer diagnostic method is that the error, defined as mechanical wear of some internal part of the automatic transmission, can in fact be caused by unreliable contacts in the wiring or the presence of oxides in the connectors. The same malfunctions are quite capable of causing jolts, delays in shifting gears, or the transitions of the "machine" to emergency mode. Therefore, in such a situation, you should not immediately dismantle and untwist the box - first you should check the condition of the wires and their joints.

This can be done independently by conducting an external inspection of the automatic transmission wiring for oxides and damage. And if a car enthusiast has a multimeter, and even knows how to use it, then checking the wires for a break should not cause difficulties. The same device will allow you to determine the presence and magnitude of voltage on certain contacts of the automatic transmission control unit.

Checking the circuit with a lamp

Diagnostics of electrical wiring without load, of course, allows you to establish the presence of an open circuit or its absence. But to evaluate in this way the state of the contact, which affects the resistance in the circuit, is very difficult.

For a deeper check of the wire, voltage is applied to one end of it, and a halogen lamp is connected to the second. If it shines dimly, it means that the line is oxidized at the joints or is broken somewhere. Only the power of the light source and the duration of such a diagnosis should be such that the connecting elements do not heat up or melt.

Insidious sensors

An example of an unsuccessful diagnosis is the story that happened with the Volkswagen Passat B5 and its automatic transmission 5HP19 from the manufacturer ZF. The car showed a malfunction, in general, typical for "automatic machines" - jerks during gear shifting.

Having diagnosed the automatic transmission, the car service specialists "prescribed" it a major overhaul, including the replacement of the valve body and clutch packs, as well as the restoration of the torque converter. But, as it turned out, this far from cheap undertaking did not bring much result.

It later turned out that the reason for the jerks was inaccurate readings of the MAF sensor... The fact is that the automatic transmission determines the required load on its engine to ensure the smooth running of the car. In this case, the interval between gear changes is set based on information received from the mass air flow sensors and the position (movement) of the rotor. Thus, their condition affects the operation of the entire box.

The moral is this: motorists who undertake to diagnose automatic transmission on their own should have an idea of the principle of its operation and the interaction of the electronic control unit of the box with other systems of the car.

Oil condition analysis

Any oil intended for an automatic transmission has its own service life. The specific timing of ATF replacement is set by the gearbox manufacturer.

It is worth considering that in many modern automatic transmissions, the torque converter lockup occurs earlier than in similar devices of the old model.The result is improved vehicle dynamics and lower fuel consumption. But along with this, a large amount of abrasive friction dust gets into the oil, clogging the channels in the valve body and damaging the working surfaces of the solenoids. Therefore, the delay in updating the lubricant for such automatic transmissions is especially undesirable.

Expired oil can be recognized by its black color, and a burnt smell from ATF is a sign of overheating of the friction elements. Severe contamination of the filter leads to a decrease in the pressure of the transmission fluid, hence the jerking when changing gears.

Free diagnostics

Large car services often offer to check the box for free... Typically, this service, which takes about half an hour on average, includes:

computer diagnostics of the electronics of cars equipped with an ECU, a motor and a gearbox;
assessment of the condition and amount of transmission fluid;
inspection of the exterior of the automatic transmission in order to detect oil leaks;
test drive a car with a service station representative.

If faults are identified during this type of check, a list of required spare parts is drawn up and the cost of repairs is announced. Even if no problems with the automatic transmission are detected, then the car owner may be offered a deeper paid diagnostics of the box with its disassembly.

Prices for automatic transmission diagnostics

A routine check of an automatic transmission in a car service will cost the car owner from 490 rubles. The average price of such a diagnosis is 1,500 rubles. The price of the service depends on the brand and model of the machine, the amount of work and the complexity of the faults, if any are known.

Oil change has its own price, which is determined taking into account the ATF renewal method, as well as the costs of the transmission fluid itself and the following expendable materials:

seals for filler and drain plugs;
oil filter;
pallet gasket.

When buying oil in the car service itself, sometimes you can get a discount on updating this fluid in the automatic transmission. On average, the price for a complete ATF replacement, including flushing the box, starts from 2800 rubles.

Dismantling and troubleshooting of automatic transmissions are paid separately. So, the price of removing and installing the box may vary depending on the type of car:

frameless, such as Ford Focus, Mercedes E230, Dodge Caravan - from 5500 rubles;
all-wheel drive with the installation of the motor across the body, for example, Toyota Rav4, Hyundai Santa Fe, Ford Escape - from 9500 rubles;
all-wheel drive with longitudinal engine placement, which include Nissan Pathfinder, BMW X3, Mitsubishi Pajero - from 10,000 rubles.

And one more circumstance that affects the cost of automatic transmission diagnostics in car services is the location of the latter. Depending on the city, a complete check of the automatic transmission, with removal and troubleshooting, can be performed approximately at the following price:

Moscow: 22,000 rubles;
St. Petersburg: 20,000 rubles;
Novosibirsk: 5100 rubles;
Izhevsk: 15,000 rubles;
Simferopol: 13,500 rubles;
Krasnoyarsk: 17800 rubles;
Yekaterinburg: 20,000 rubles;
Rostov-on-Don: 10,000 rubles;
Chelyabinsk: 20,000 rubles;
Tyumen: 5000 rubles.

Conclusion

If the automatic transmission urgently needs diagnostics, and the owner of this unit is sorry for the time or money to visit the service station, then the motorist can try to perform such a check on his own. Of course, for this you need to have a certain understanding of the structure of an automatic transmission and the principles of its operation. Specialized equipment will not hurt either, at least the same OBD II adapter. Attempts to fix problems by the "scientific poke" method will only bring the car closer to a visit to a car service.