Audi A4

since 1994 of release

Repair and car operation

A4 Audi
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ exhaust System
+ cooling System
+ Fuel tank and fuel pump
+ Air filter and absorption channels
+ injection System
+ Coupling
- Transmission and main transfer
   Mechanical transmission
   Noise in a transmission
   Automatic transmission
   Electronic control by a transmission
   Main transfer
   Power shafts
   Check of cuffs of power shafts
   The help at malfunctions
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tires
+ Electrotechnical equipment
+ ignition System
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ body Details
+ Salon
Search of malfunctions
Technical characteristics

Electronic control by a transmission

In planetary transfer all gear wheels are constantly linked. Various steps of transfer are reached without a rupture of draft by starting or keeping of a solar wheel, planetary gear wheels or a ring gear wheel of planetary transfer.
1–the details actuated;
2–withheld details.

Entrance signals

In the electronic control unit information arrives from:

  • the lever selector with the multipurpose switch of situation. Installation of the lever inclusion of lamps of a backing, the blocking mechanism of a starter copes at the included range of change of transfers, and also turning on/switching off of the device of adjustment of speed;
  • butterfly valve potentiometer about its situation. It is the knot known on injection, serves for calculation of points of gear shifting;
  • the sensor of speed in a transmission for determination of speed of movement, and also gear shifting points. If this sensor is faulty, the signal from the Hall sensor undertakes;
  • the sensor about number of turns on a transmission entrance. Also settles down on a transmission and serves for definition of points of gear shifting;
  • the accelerator sensor in a butterfly valve cable; it gives a signal when the pedal of gas is wrung completely out. After that there is a switching on higher transfer or if it is necessary, there is a switching down on one or two ranges of change of transfer number;
  • the switch of brake fires for unblocking of electromagnetic blocking of the lever selector. The lever selector moves from the situation "R" or "N" in one of ranges of change of transfer number only at the pressed pedal of a brake;
  • the sensor of temperature of ATF in a transmission. When in the control unit of the engine the signal «the increased temperature» arrives, in separate ranges of change of transfer number there is a switching on higher level. It reduces a gap in the hydrotransformer and reduces ATF temperature – after it there is a switching on the standard program.

Management of gear shifting process

If you move the lever selector to the situation "D", ATF, being under pressure, arrives in so-called switching zaslonka in a box which in turn operate in the hydraulic way lamellar couplings and brakes. The control unit regulates pressure by means of electromagnetic valves and, in such a way, defines the switching moment on higher or low transfer, and also switching transitions. At the same time there is a communication with the control unit ignition/injection – when switching on higher transfer the moment of ignition is slightly removed in order that switching proceeded softly.

Signals from the control unit arrive further to an electromagnet of blocking of the lever selector, the combined relay of blocking of a starter and to backing lamps. If Audi A4 is supplied with system of adjustment of speed, the control unit submits automatic equipment of a transmission on it tension only when the range of change of transfer number of forward transfer is included and speed of 30 km/h is for the first time exceeded.


The control unit of an electronic transmission can distinguish arising defects and to keep them in the computer. Arising failures are remembered in a long-term memory. The memory can be interrogated in a workshop. It becomes by means of the reading-out device; unfortunately, possibility for computer poll by the fan is not provided. If you assume malfunction existence in management of a transmission, consider memory of the computer you can only in Audi workshop.

Emergency course

4-step AKP

If the control unit distinguished defect which makes essential negative impact on functioning, or the control unit is faulty, the mode of «an emergency course» joins. For this purpose there are two emergency programs:

  • If the lever selector is in situation "D", "3" or "2", the transmission a hydraulic way includes the 3rd transfer. The chosen range of change of transfer number joins only in positions of the lever selector "1" and "R".
  • If the signal about number of turns of the engine and speed does not arrive and the pressing of a pedal of an accelerator for the first time exceeds value ѕ, the transmission is switched to «N» step, i.e. there is no more drive. By switching off of ignition and new start of the engine you can try to make active a transmission again.

Emergency course

Transmission 5-NR-18

The transmission has different modes of an emergency course depending on nature of malfunction:

  • At insignificant failure movement is carried out on other program of gear shifting.
  • At defect in a mechanical part of knot of gear shifting during movement the transmission remains included at the 4th step. Then after switching off of the engine the 3rd range of change of transfer number joins just.

Check of an automatic transmission

The automatic transmission practically does not leave to the fan of possibilities for his initiative. But purposeful check will help to localize malfunction that not least is of interest upon purchase of the second-hand car:

  • In the presence of malfunction first of all check ATF level in a transmission.
  • If ATF on щупе for its measurement smells burned, there is a heavy damage of a transmission. In this case brake tapes or coupling plates can be defective.
  • At a trial trip you can check gear shifting points.
  • How there is a gear shifting process, gives information on a transmission condition.
  • Adjustment of a cable of a butterfly valve with the integrated mechanism of switching by sharp pressing of a pedal of gas is an important condition of a faultless operating mode.
  • The same treats adjustment of a cable of the lever selector.

Assessment of process of gear shifting

During a trial trip you can pay the attention to gear shifting process:

Switching on higher transfer: at partially wrung out pedal of gas transfer change almost is not felt; at full gas or sharp pressing a gas pedal transitions become more distinct, but higher transfer should seize always softly. Short increase of frequency of rotation of the engine at change of transfer indicates defect which should be studied more attentively.

Switching on lower transfer: without gas (at a kacheniye) it is hardly notable on very low speeds. The push when switching on a backing on partial or full gas is normal. Return switching without gas the lever selector lasts one-two seconds. If at compulsory switching back the lever selector gas at the same time increases, gear shifting occurs without delay.

 Council: Cars with an automatic transmission cannot be towed on the distance exceeding 50 km, otherwise it will appear a transmission insufficient greasing. For the same reason speed of movement should not exceed 50 km/h. At towage the lever selector should be in the situation "N". In a doubtful case choose more convenient way and ship the car.