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
+ Wheels and tires
+ Electrotechnical equipment
+ System of ignition
+ Lighting
+ Alarm equipment
- Tools and devices
   Check of control tools and bulbs
   The combined device
   Indicator of amount of fuel
   Indicator of temperature of cooling liquid
   Auxiliary devices
   Control bulbs above in the combined device
   Control bulb of cooling liquid
   Control bulb of level of brake fluid
   Control bulb of pressure of oil
   Control bulb of indexes of turns
   Control bulbs in devices of a round form (and nearby)
   Control bulb of indexes of turn on the trailer
   Control bulb of ASR
   Control bulb of the lock of ignition
   Control bulb of headlights of a driving beam
   Control bulb of a safety cushion
   Control bulb of ABS
   Control bulb of the parking brake
   Control bulb of a battery charging
   System of autocontrol of the car
   Ignition lock
   Check of switches
   Alarm buzzer of lighting
   The warmed back glass
   Check of screen wipers and windscreen washers
   Engine of screen wipers
   The help at malfunctions
   The gulf of liquid for washing of glasses
   System of washing of headlights
   Adjustment of a mirror with the electric drive
   Central lock
   Window regulators with the electric drive
   Sliding/removable roof with the electric drive
   Radio receiver
   The antenna on back glass
+ Heating and ventilation
+ body Details
+ Salon
Search of malfunctions
Technical characteristics


Speedometer in Audi A4, differently also could not be, is the electronic measuring device as well as the measuring instrument of number of turns. It also processes impulses of number of turns which he (not as a tachometer) receives from the sensor on a transmission. There it is measured, with what frequency wheels rotate.

The signal of rotation of wheels is used as measuring size for run definition, and also in operation of the indicator of an interval of maintenance, the fuel consumption indicator, in volume control of a sound of the radio receiver and in operation of the on-board computer. Therefore there was an idea to send this signal and to a speedometer and to refuse a shaft of a speedometer which provides the drive in old mechanical speedometers.

If the speedometer does not work, in the beginning check the corresponding safety lock in a box of safety locks (the head the Electrotechnical equipment).

Run counter

Indication of the general and day run in Audi A4 is carried out by the liquid crystal display. That it was impossible to manipulate data on run – data on run continuously remain in the memory independent of giving of tension and the combined device which is in.

Pulse sensor of a speedometer

Impulses of rotation of wheels move in a speedometer the sensor with gerkonovy contact behind on a transmission. Gerkonovy contact represents the block of contacts which are placed in an air-tight gas cover. Contact becomes isolated in case it is influenced by an electromagnetic field.

In order that gerkonovy contact could give out sequence of impulses, it has to open and be closed in beat frequencies of rotation of wheels. Therefore the wheel with dredging which rotates in front of the sensor, influences the magnetic field influencing the block of contacts.

Check of the pulse sensor of a speedometer


  1. Lift the left forward wheel.
  2. Press a fixing clip on the socket and remove the socket.
  3. Connect an ohmmeter to both contacts of the sensor.
  4. Now slowly turn a hand the left forward wheel: the indicator of an ohmmeter has to fluctuate between 0 Ohms and Ohm.
  5. If it not so, replace the sensor.

Dismantle of the pulse sensor of a speedometer


  1. Press a fixing clip on the socket and remove the socket.
  2. Slightly press a clamp of a fixing clip of the sensor down and slightly turn the sensor to the right.
  3. Take out the sensor from a transmission.
  4. At installation track correctness of installation of sealing rings.