Audi A4

since 1994 release

Repair and operation of the car

A4 Audi
+ 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
+ Suspension bracket of wheels and steering
- Brakes
   Independent work on brake system
   So the brake system works
   Check of brakes
   Brake fluid
   Check of level of brake fluid
   Check of brake system on tightness and existence of damages
   Replacement of brake fluid
   Disk brakes
   Measurement of thickness of overlays of forward disk brakes
   Check of a condition of brake disks
   Replacement of overlays of disk brakes
   Back disk brakes
   Measurement of overlays of back disk brakes
   Emergency brake
   Check of idling of the lever of the emergency brake
   Main brake cylinder
   Brake amplifier
   Check of the brake amplifier
   Works on hydraulics of brake system
   Pumping of brake system
   The help at malfunctions
   ABS and EDS
   What does ABS?
   Function of separate knots
   Electronic system of distribution of brake effort (EBV)
   Violations in work of ABS system
   Electronic blocking of differential (EDS)
+ 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 blocking of differential (EDS)

Electronic blocking of differential (Elektronische Differential-Sperre) does not work in the main transfer by means of a mechanical peremykaniye of differential or by means of friction surfaces as it complicates a steering and the movement on turns. The letter "e" in EDS abbreviation already speaks about use of electronics – in combination with system of anti-blocking:


  1. When in a start of motion the forward wheel rotates, about it learn sensors of number of turnovers of various value of frequency of rotation of wheels.
  2. The combined ABS and EDS control unit puts in action a disk brake on the turned wheel. It is carried out at the expense of additional pair of electromagnetic valves in the hydraulic ABS module. ABS opens connection from pressure collector to the wheel cylinder of the corresponding disk brake until the wheel does not slow down so that other forward wheel can transfer effort.
  3. As soon as on both wheels there are identical conditions of pro-slipping, the control unit finishes process of adjustment and closes electromagnetic valves. The driver does not need to interfere, he notices blocking of differential only on change of nature of noise.
  4. To exclude failure, EDS is controlled by the scheme of blocking. On the basis of pressure of brakes, and also after the determined maximum period of time of EDS it is disconnected to avoid an overload of brakes. At a speed over 40 km/h of EDS it is disconnected always. Schemes of electromagnetic valves are so calculated that forward brakes cannot work without control.
  5. If the control unit distinguishes failure in work of EDS, EDS is disconnected. The system of anti-blocking continues to function. In all cases of Audi it is ready to braking at any time.
  6. The device of storing of malfunctions works the same as is described in the section on ABS.