All models described in this manual are equipped with a second generation on-board diagnostic system (OBD II). The main element of the system is the onboard processor, often called the electronic control unit (ECM), or a control unit for the operation of the power unit (RSM). The PCM is the brain of the engine management system. The initial data is fed to the unit from various information sensors and other electronic components (switches, relays, etc.). Based on the analysis of the data coming from the information sensors, and in accordance with the basic parameters stored in the processor's memory, the PCM generates commands for the operation of various control relays and actuators, thereby adjusting the operating parameters of the engine, and ensuring maximum efficiency of its output with minimal fuel consumption. Reading the OBD-II processor memory data is performed using a special scanner connected to the 16- or 38-pin diagnostic connector for reading the database (DLC), located inside the car.
Note. In principle, reading the fault codes recorded in the memory of the self-diagnosis system is possible, on some models, using an auxiliary LED, as well as using the codes displayed on the display of the automatic KV.
Information about diagnostic tools
Checking the correct functioning of the components of the injection systems and reducing the toxicity of exhaust gases is carried out using a universal digital meter (multimeter). The use of a digital meter is preferred for several reasons. Firstly, it is quite difficult for analog devices to (sometimes impossible), to determine the result of the indication with an accuracy of hundredths and thousandths, while when examining circuits that include electronic components, such accuracy is of particular importance. The second, no less important, reason is the fact that the internal circuit of a digital multimeter has a fairly high impedance (the internal resistance of the device is 10 MΩ). Since the voltmeter is connected in parallel to the circuit under test, the measurement accuracy is higher, the smaller the current will pass through the device itself. This factor is not significant when measuring relatively high voltage values (9 - 12 V), however, it becomes decisive in the diagnosis of elements that produce low-voltage signals, such as, for example, a lambda probe, where we are talking about measuring fractions of a volt.
Parallel monitoring of signal parameters, resistances and voltages in all control circuits is possible using a splitter connected in series to the engine control unit connector. At the same time, with the engine turned off, running or while the car is moving, the parameters of the signals at the splitter terminals are measured, from which a conclusion is made about possible defects.
To diagnose electronic systems of the engine, automatic transmission, ABS, SRS and others, special diagnostic scanners or testers with a specific cartridge can be used (if provided), universal cable and connector. In addition, for this purpose, you can use an expensive specialized automotive diagnostic computer, specially designed for the complete diagnosis of most systems of modern cars (e.g. ADC2000 from Launch HiTech). Also, for this purpose, you can use scanners and specialized diagnostic analyzers, such as FDS 2000, Bosch FSA 560, KTS 500 (0 684 400 500) or a regular personal computer with a special controller, cable (e.g. kit 1 687 001 439) and installed by the program browser OBD II.
Some scanners, in addition to the usual diagnostic operations, allow, when connected to a personal computer, to print circuit diagrams of electrical equipment stored in the memory of the control unit (if laid down), program the anti-theft system, observe the signals in the car circuits in real time.