Audi A4

since 1994 release

Manual of the car

Audi A4
+ Running gear
+ Regular servicing
+ Engines
+ Turbo-supercharging
+ System of an exhaust
+ Cooling system
+ Fuel tank and fuel pump
+ Air filter and channels of absorption
+ System of injection
+ Coupling
- Transmission and main transfer
   Mechanical transmission
   Noise in the transmission
   Automatic transmission
   Electronic control by the 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
+ System of ignition
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ Body details
+ Salon
Search of malfunctions
Technical characteristics


Electronic control by the transmission

In planetary transfer all gear wheels are constantly linked. Various steps of transfer are reached without 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 set in motion;
2 – the withheld details.

Entrance signals

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

Management of gear shifting process

If you move the lever selector to situation "D", ATF, being under pressure, comes to the so-called switching gates 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 moment of switching to higher or low transfer, and also switching transitions. At the same time there is a contact with the control unit of ignition/injection – when switching to higher transfer the moment of ignition is slightly removed in order that switching proceeded softly.

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


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

Emergency course

4-staged AKP

If the control unit distinguished defect which exerts significant negative impact on functioning, or the control unit is faulty, the mode of "the emergency course" joins. For this purpose there are two emergency programs:

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

Emergency course

Transmission 5-HP-18

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

  • At insignificant failure the movement is carried out on other program of gear shifting.
  • At defect in a mechanical part of knot of gear shifting during the 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 the automatic transmission

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

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

Gear shifting process assessment

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

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

Switching to lower transfer: without gas (when swing) it is hardly notable at very low speeds. The push when switching to a backing on partial or full gas is normal. The 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, then gear shifting happens without delay.

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