Audi A4, S4

Since 2000 of release

Repair and car operation



Audi A4, S4
+ Introduction
+ Controls and receptions of safe operation
+ Current leaving and service
+ The engine
+ Systems of cooling, heating and the air conditioner
+ Power supply systems, release and decrease in toxicity of the fulfilled gases
- Systems of an electric equipment of the engine
   + Ignition and engine management system
   + System of preheat of the diesel engine
   - Diagnostics of systems of electronic control and the diagnostic equipment
      The general data
      Diagnostics of electronic control systems by the engine, injection, ignition and auxiliary brake systems
      The controller of interface of the personal computer with onboard system of self-diagnostics OBD II under reports of standards SAE (PWM and VPW) and ISO 9141-2
      Application of an oscillograph for supervision of signals in chains of control systems
   + Gymnastics and start systems
+ Manual box of a gear change
+ Automatic transmission
+ Coupling, power shafts and differential
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment



Diagnostics of systems of electronic control and the diagnostic equipment

The general data

System OBD structure includes some the diagnostic devices making monitoring of separate parametres of systems of decrease of toxicity and fixing revealed refusals in memory of the onboard processor in the form of individual codes of malfunctions. The system makes also check of gauges and actuation mechanisms, supervises vehicle service cycles, provides storing possibility even failures quickly arising in the course of work and clearing of the block of memory.

All models described in the present Management are equipped by system of onboard diagnostics of the second generation (OBD II). A system Basic element is the onboard processor, more often named the electronic block of management (ЕСМ), or the block of management of functioning of the power unit (РСМ). РСМ is a brain of a control system of the engine. The initial data arrives on the block from various information gauges and others electronic a component (switches, the relay etc.) . On the basis of the analysis of the data arriving from information gauges, and according to put in memory of the processor in base parametres, РСМ develops commands on operation of various operating relays and actuation mechanisms, carrying out thereby updating of working parametres of the engine, and providing peak efficiency of its return at the minimum expense of fuel. Data read-out of memory of processor OBD-II is made by means of the special scanner connected to a 16-contact diagnostic socket of reading of a database (DLC), located in car salon.

Basically, reading written down in memory of system of self-diagnostics of codes of malfunctions probably, on some models, by means of an auxiliary light-emitting diode, and also on the codes highlighted on the display automatic SQ.

Data on diagnostic devices

Check of serviceability of functioning a component of systems of injection and decrease in toxicity of the fulfilled gases is made by means of a universal digital measuring instrument (multimeter). Use of a digital measuring instrument preferably for the several reasons. First, on analogue devices it is difficult enough (at times, it is impossible), to define result of the indication to within the 100-th and thousand shares while at inspection of the contours including in the structure electronic components, such accuracy takes on special significance. The second, the reason that fact is not less important that the internal contour of a digital multimeter, has high enough impedance (internal resistance of the device makes 10 МОм). As the voltmeter is connected to a checked chain in parallel, accuracy of measurement by that above, than the smaller current will pass through actually device. The given factor is not essential at measurement concerning high values of pressure (9 - 12), however there is defining at diagnostics of elements giving out low-voltage signals, such, as, for example, a ljambda-probe where it is a question of measurement of shares of volt.

Parallel supervision of parametres of signals, resistance and pressure in all chains of management is possible by means of a splitter included consistently in a socket of the block of engine management. Thus on the switched off, working engine or during car movement, measurement of parametres of signals on splitter plugs from what the conclusion about possible defects becomes is made.

For diagnostics of electronic systems of the engine, automatic transmission, ABS, SRS and other special diagnostic scanners or testers with a certain cartridge (if it is provided), a universal cable and a socket can be applied. Besides, it is possible to apply the expensive specialised automobile diagnostic computer specially developed for full diagnostics of the majority of systems of modern cars to this purpose (for example, ADC2000 firms Launch HiTech). Also, it is possible to apply scanners and specialised diagnostic analyzers to this purpose, for example VAG1551, FDS 2000, Bosch FSA 560, KTS 500 (0 684 400 500) or the usual personal computer with the special controller, a cable (for example, the complete set 1 687 001 439) and the established program browser OBD II.

Some scanners, besides usual operations of diagnostics, allow, at connection with the personal computer, to unpack stored in memory of the block of management basic schemes of an electric equipment (if are put), to program anticreeping system, to observe signals in car chains in real time.