Audi 80/Avant (B4)

since 1991-1995 release

Repair and operation of the car

Audi 80/Avant
+ Technical specification
+ Engines
+ System of production of the fulfilled gases
+ Cooling system
+ Fuel tank and fuel pump
+ Air filter and airintaking channels
+ System of injection
+ Coupling
- Transmission and transmission
   Removal and installation of the mechanical transmission (T)
   Noise in a transmission
   Automatic Transmission (AT)
   Electronic control of AKP
   Main transfer
   Power shafts
   Check of cuffs of power shafts
   List of malfunctions
+ Suspension bracket and steering
+ Brake system
+ Anti-blocking system of brakes
+ Wheels and tires
+ Body electrical system
+ System of ignition
+ Lighting
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ body Elements
+ Search of malfunctions
+ Specifications

Electronic control of AKP

The scheme does by more evident communications between the block of valves of switching (1) AKP, the lever of the selector (2) the multipurpose switch (3) and the electronic control unit (4). The manual valve (5) is set in motion directly by the switching lever.

Entrance signals

The control unit processes numerous signals from various knots; information arrives from:

  • The AKP selector lever with the multipurpose switch. Management of inclusion of headlights of a backing, blocking of a starter at the included mode of the movement depends on position of the lever and management of change of the movement mode of system.
  • The Sport button including the sports program of switching.
  • Potentiometer of a butterfly valve about the provision of a butterfly valve. This acquaintance on system of injection an element serves for definition of the moments of switching.
  • The speed sensor in AKP for determination of speed of the movement also for the switching moments. In case of malfunction of this sensor the control unit uses the frequency of rotation of a shaft of the engine (from the Hall sensor) as a spare indicator.
  • The sensor of limit provision of a pedal of an accelerator in the hummock drive of "gas"; he reports if the pedal of an accelerator was squeezed completely out. In this case switching on an overgear happens later, in need of AKP switches to two ranges down.
  • The braking signal switch for removal of blocking of the lever of switching. The switching lever from the situation "P" or "N" in one of ranges of the movement can be moved only at the squeezed-out brake pedal.
  • The sensor of temperature of ATF reporting about liquid temperature in AKP. Considerable heating of ATF can come a consequence of strong distinction of number of turns between the engine and AKP. If the signal "the increased temperature" comes to the control unit,

AKP in the separate ranges switches to an overgear later. It reduces slipping in the hydrotransformer and reduces ATF temperature – then again there is a switching on the usual program of the movement.

Management of switching processes

If you move the selector lever in the situation "D", being under pressure of ATF gets to so-called valves of switching in the block of valves which, in turn, hydraulically operate multidisk couplings and multidisk brakes. The Digimat control unit regulates pressure by means of electromagnetic valves and thus defines a timepoint for switching on the raised or low gear, and also switching transitions. Contact with the control unit of systems of injection/ignition is at the same time kept – when switching on an overgear the ignition moment moves a little back in order that transition of switching took place smoothly.

Teams from the control unit get further on a magnet of blocking of the lever of switching, the relay of blocking of a starter and headlights of a backing and the light indicator in the Sport button. If the Audi 80 car is equipped with system of regulation of speed, food on it starts moving with the control unit only when one of ranges of advance and speed for the first time is included reached border of 30 km/h.

Independent diagnostics

The AKP control unit can distinguish and write down the arising malfunctions. The control program watches entrance and output signals practically of all sensors and knots, and also their electric chains. The arising malfunctions register in long-term memory of the store. At the corresponding check in a workshop memory of the store is read out by means of the special device. Possibility of check of memory of the store in house conditions does not exist. Even if you assume existence of malfunction in management of AKP, you will be able to interrogate memory of the store of malfunctions only in Audi workshop.

Operation in extraordinary conditions

If the control unit recorded the malfunction significantly influencing functioning or if the control unit is faulty, it switches in the "operation in extraordinary conditions" mode. For this purpose there are two programs:

  • As well as before failure detection, AKP switches automatically to the raised or low gear, but breakthroughs when switching become considerably more expressed.
  • AKP does not switch automatically to the raised or low gear any more. In provisions of the lever of the D, 3 and 2 selector on hand there is only the third range. Only in the provisions "1" and "R" the chosen range really joins.
    In both cases it is necessary to visit urgently Audi workshop where first of all memory of the store of malfunctions will be interrogated.

Check of AKP

AKP almost does not give opportunities for manifestation of own initiative in house conditions. Purposeful checks, however, help to estimate a cause of defect that is not least interesting upon purchase of the second-hand car:


  1. At malfunctions first of all it is necessary to check the ATF level in AKP.
  2. If ATF on a tip of the probe smells burned down, so there is a serious damage of AKP. In this case multidisk couplings or brake tapes are defective.
  3. During a trial trip it is possible to check the switching moments.
  4. From this, how there are switching processes, it is possible to draw a conclusion on a condition of AKP.
  5. Regulation of the hummock drive of gas with the integrated sensor of limit provision of a pedal of an accelerator – an important condition for excellent job.
  6. The same can be told about regulation of the hummock drive of the lever of the selector.

Supervision over switching processes

During a trial trip you have to pay the attention to switching processes:

  • Switching on an overgear: at incompleteness of the squeezed-out accelerator pedal switching is almost imperceptible; at completely squeezed out accelerator pedal (at start-off from a place or during the movement) gear shiftings become more noticeable, but the overgear has to join smoothly. Short-term increase of turns at change of transfers indicates malfunctions in which it is necessary to be engaged more densely.
  • Switching on a low gear: at the released accelerator pedal (at the movement by a setup) and very low speeds almost imperceptibly. Breakthrough when switching on a low gear on incomplete or full "gas" is quite normal. Switching on a low gear the selector lever at the released pedal of an accelerator lasts 1 — 2 pages. If when switching the lever of the selector at the same time squeezes out an accelerator pedal, change of transfers has to happen immediately.

 Help: Audi 80 with an automatic transmission cannot be towed further, than on 50 km, differently there is no AKP greasing. For the same reason when towing it is impossible to exceed the maximum speed in 50 km/h. In somnenitelny cases it is better to choose shorter way or to call the wrecker.

Removal of AKP

The car needs to be raised and reliably to record. You will also need a big garage jack for support and lowering to very heavy AKP down.


  1. To disconnect the accumulator.
  2. To disconnect a wire tip to the tachometer sensor.
  3. At models with the 6-cylinder engine to remove the inlet channel. For this purpose to disconnect vacuum hoses, to remove an airwater hose and to turn out fixing bolts.
  4. At models with the divided bulk branch pipe of ATF to weaken it above and to extend. To stop up the lower part of a branch pipe with not fibrous rag.
  5. To turn out the bolts connecting the engine and AKP which it is possible to reach from above.
  6. To raise cooling system hoses.
  7. To bring reliable support under the engine to prevent capsizing.
  8. To turn off the lower panel of a motor compartment.
  9. To remove thermal protection of the leading half shaft.
  10. To remove body traverses below an exhaust pipe or catalytic converters (depending on engine type).
  11. To remove exhaust pipes (at models with the 6-cylinder engine together with catalytic converters).
  12. To disconnect power shafts from a transmission (without allowing them to fall).
  13. To remove a starter. Thanks to it access to fixing bolts of the hydrotransformer opens.
  14. To substitute capacity under bolted connections of ATF lines.
  15. To separate the pipeline to ATF cooler at the level of the oil pallet.
  16. To turn off fastenings for the ATF pipeline and to take hoses aside.
  17. To weaken in total three bolts of the hydrotransformer from the engine.
  18. For this purpose to hold the central bolt of a pulley or a damper (depending on engine type) by means of a cap wrench. To turn a cranked shaft respectively on 1/3 turns.
  19. To turn off a heat-shielding of the multipurpose switch.
  20. To remove the plug on the AKP case. After that to remove from loops trosoderzhatel of procon-ten system and to wring out cables upward.
  21. To turn off a forward arm of the engine.
  22. To raise AKP by means of a garage jack and to weaken bolts of fastening of AKP.
  23. Slightly to overturn the engine connected to AKP back; after that again to bring a strong support under the engine.
  24. To turn off a six-sided bolt of a rubber-metal support of an arm of AKP behind.
  25. To turn out the lower connecting bolts, the fixing AKP to the engine.
  26. To wring out AKP from the engine; if necessary to use mount.
  27. Carefully to lower AKP.
  28. At removal of AKP to wring out the hydrotransformer.
  29. The hydrotransformer has to remain together with AKP! Watch closely that it did not drop out (to fasten a wire).

Installation of an automatic transmission

Installation happens logically in the return sequence in comparison with removal. The special attention is deserved by the next moments:


  1. To check, whether correctly in AKP the hydrotransformer is installed. To watch that at installation it did not move forward.
  2. For fastening of the hydrotransformer to a flywheel it is necessary to use original bolts, differently the hydrotransformer will be destroyed.
  3. At installation in the last turn to twirl bolts of a rubber-metal support. Before it to correct a support so that the core of a support was in the middle of the case.
  4. To establish a podkladny washer 13 mm thick between a countersupport of a tube of the ATF and AKP cooling system.
  5. If necessary to fill in new ATF.
  6. To establish an exhaust pipe.
  7. To adjust the selector lever.

Moments of an inhaling of fastenings of AKP

N • m
Primary shaft to Akpgidrotransformator to makhovikuakp to the engine
Arm to AKP
AKP arm to a body