Mercedes-Benz G-class (W463) since 1999 of release
1. Introduction
2. Governing bodies and operation receptions
3. Current leaving and service
4. Engine
5. Systems of cooling, heating, ventilation and air conditioning
6. A power supply system and production of the fulfilled gases
7. Systems of electric equipment of the engine
7.1. Ignition and engine management systems
7.2. System of preheat of the diesel engine
7.3. Diagnostics of systems of electronic control and diagnostic equipment
7.3.1. General information
7.3.2. The controler of interface of the personal computer with onboard system of self-diagnostics of OBD II according to protocols of the SAE standards (PWM and VPW) and ISO 9141-2
7.3.3. Oscillograph application for supervision of performance data of a control system
7.4. Charging and start systems
8. Automatic transmission
9. Transmission line
10. Brake and auxiliary systems
11. Suspension bracket and steering
12. Body
13. Onboard electric equipment
14. Schemes of electric connections



7.3.1. General information

General information

System of onboard self-diagnostics

The structure of OBD system includes some diagnostic devices making monitoring of separate parameters of systems of decrease in 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 sensors and actuation mechanisms, supervises vehicle service cycles, provides storing possibility even failures quickly arising in the course of work and cleaning of the block of memory.

All models described in the real Management are equipped with system of onboard diagnostics of the second generation (OBD II), which basic element is the onboard processor more often called by the electronic module of management (ECM - further), or more rare) the module of management of functioning of the power unit (RSM).

ECM is a brain of a control system of the engine. Basic data arrive on the module from various information sensors and other electronic components (switches, the relay etc.). On the basis of the analysis of data arriving from information sensors, and according to put in memory of the processor in base parameters, ECM develops commands for operation of various operating relays and actuation mechanisms, carrying out thereby adjustment of working parameters of the engine, and providing maximum efficiency of its return at the minimum fuel consumption. The scheme of an arrangement of electronic modules of management of various systems of the car is shown on an illustration of the Detail of installation of the module of management of a forward door.

Data read-out of memory of the OBD II processor (ECM) is made by means of the special scanner connected to the 16-contact diagnostic socket of reading of a database (DLC). By means of the same scanner cleaning of memory of the processor is carried out also. And cleaning of memory of ECM it will be reasonable to charge performance of procedures of reading of the DTC codes to specialists of car-care center.

On some models reading of the ECM codes of malfunctions (DTC) written down in memory in principle can be made by means of an auxiliary light-emitting diode, and also on the codes highlighted on the display automatic К/В.

The DLC socket is located at the left under the car dashboard

Identification of plugs of the 16-contact diagnostic socket (DLC)

3 — TNA Signal
4 — Connection with the case, the plug 31
5 — the Case - an alarm conclusion, the plug 31
6 — the Tyre of data of CAN high level
7 — engine (ME) Electronics
8 — a Food, the plug 87
9 — Antiprobuksovochnaya system (ETS)

11 — the Control unit transmission (ETC)
12 — the Module of activity (AAM)
13 — safety Systems
14 — the Tyre of data of CAN Low level
15 — IC a combination of devices
16 — battery Plus through a safety lock. Energized at any position of the lock of ignition, the plug 30

Data on diagnostic devices

Multimeter connection to control unit sockets the engine by means of an auxiliary splitter

Check of serviceability of functioning of components 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 several reasons. First, on analog devices it is rather difficult (sometimes - 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 rather high impedance (internal resistance of the device makes 10 megohms). As the voltmeter is connected to a checked chain in parallel, accuracy of measurement by that is higher, than the smaller current will pass through actually device. This factor is not essential at measurement of rather high values of tension (9 ÷ 12 In), however there is defining at diagnostics of elements giving out low-voltage signals, such, as, for example, a lambda probe where it is a question of measurement of shares of volt.

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

Special diagnostic scanners or testers can be applied to diagnostics of electronic systems of the engine, automatic transmission, ABS, SRS and other with a certain cartridge (if it is provided), a universal cable and the socket. Besides, it is possible to apply the expensive specialized automobile diagnostic computer which has been specially developed for complete diagnostics of the majority of systems of modern cars to this purpose (for example, Launch HiTech firm ADC2000). Also, it is possible to apply scanners and specialized diagnostic analyzers to this purpose, for example FDS 2000, Bosch FSA 560 (, KTS500 (0 684 400 500) or the ordinary personal computer with the special adapter, a cable (for example, a set 1 687 001 439) and the established program OBD II browser.

For diagnostics of your car you can download the free version of a browser of OBD II also from a site of originators of the real Management of http//

Some scanners, besides usual operations of diagnostics, allow, at connection with the personal computer, to unpack being stored in memory of the control unit schematic diagrams of electric equipment (if those are put), to program anticreeping system, to observe signals in car chains in real time.

Reading of diagnostic codes and cleaning of memory of the processor

The scheme of connection of the STAR DIAGNOSIS (0100) input reader to the diagnostic DLC socket (X11/4)

Reading of the DTC codes and cleaning of memory of the processor of system of onboard self-diagnostics is carried out by means of the firm STAR DIAGNOSIS (0100) scanner connected to the 38-contact DLC socket (X11/4) of the car.

Having connected the input reader to the DLC socket, include ignition and start system of authorization of the driver (DAS).

In the MODEL DESIGNATION menu of the input reader choose the FIRTHER MODEL SERIES point, further act according to displayed instructions depending on an objective (reading of codes, memory cleaning and so forth).

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7.3.2. The controler of interface of the personal computer with onboard system of self-diagnostics of OBD II according to protocols of the SAE standards (PWM and VPW) and ISO 9141-2