On-board self-diagnosis system
The OBD system includes several diagnostic devices that monitor individual parameters of the toxicity reduction systems and fix the detected failures in the on-board processor memory in the form of individual fault codes. The system also checks sensors and actuators, controls vehicle maintenance cycles, provides the ability to store even short-term failures during operation and clear the memory block.
All models described in this manual are equipped with a second generation on-board diagnostic system (OBD II), the main element of which is the onboard processor, more often called the electronic control module (ECM - next), or (less often) power unit operation control module (RSM).
The ECM is the brain of the engine management system. The initial data is fed to the module 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 memory, the ECM generates commands for the operation of various control relays and actuators, thereby adjusting the engine's operating parameters and ensuring maximum efficiency of its return with minimal fuel consumption. The layout of the electronic control modules of various vehicle systems is shown in the illustrationFront Door Control Module Installation Details.
Reading OBD II processor memory data (ECM) produced using a special scanner connected to the 16-pin diagnostic connector for reading the database (DLC). With the help of the same scanner, the processor memory is also cleared. Performing the procedures for reading DTCs and clearing the ECM memory would be wise to entrust car service specialists.
Note. On some models, reading fault codes stored in the ECM memory (DTC) in principle, it can be done using an auxiliary LED, as well as by codes displayed on the display of automatic A/C.
The DLC connector is placed on the left under the car's dashboard
16-pin diagnostic connector terminal identification (DLC)
1 -; 2-; 3 - TNA signal; 4 - Connection to the body, terminal 31; 5 - Housing - signal output, terminal 31; 6 - CAN data bus high level; 7 - Engine electronics (ME); 8 - Power, terminal 87; 9 - Anti-slip system (ETS); 10 -; 11 - Transmission control unit (ETC); 12 - Activity module (AAM); 13 - Security systems; 14 - CAN data bus Low level; 15 - IC instrument cluster; 16 - Plus batteries through the fuse. Energized in any position of the ignition switch, terminal 30
Information about diagnostic tools
Connecting a multimeter to the connectors of the engine control unit using an auxiliary splitter
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 it's 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 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 (For example, ADC2000 from Launch HiTech). Also, for this purpose, you can use scanners and specialized diagnostic analyzers, for example FDS 2000, Bosch FSA 560, KTS500 (0 684 400 500) or a regular personal computer with a special adapter, cable (For example, set 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 any), program the anti-theft system, observe the signals in the car circuits in real time.
Read diagnostic codes and clear processor memory
STAR DIAGNOSIS reader connection diagram (0100) to the DLC diagnostic connector (Х11/4)
Reading DTCs and clearing the memory of the processor of the on-board self-diagnosis system is carried out using the proprietary STAR DIAGNOSIS scanner (0100), connected to the 38-pin DLC connector (Х11/4) car.
After connecting the reader to the DLC connector, turn on the ignition and start the driver authorization system (DAS).
On the menu «MODEL DESIGNATION» reader select item «FIRTHER MODEL SERIES», then proceed according to the instructions displayed on the screen, depending on the task (reading codes, clearing memory, etc.).