Contents: On-board diagnostic system ↡ Information about diagnostic devices ↡ Read diagnostic codes and clear…↡
On-board diagnostic system
The OBD system includes several diagnostic devices that monitor individual parameters of the toxicity reduction systems and record detected failures in the on-board processor memory in the form of individual fault codes. The system also checks sensors and actuators, monitors vehicle maintenance cycles, and provides the ability to memorize 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 diagnostics system (OBD II), the main element of which is an on-board processor, more often called an electronic control module (ECM - next), or (less commonly) the powertrain control module (PCM).
The ECM is the brain of the engine management system. Input data is supplied to the module from various information sensors and other electronic components (switches, relays, etc.). Based on the analysis of data received from information sensors, and in accordance with the basic parameters stored in the processor memory, the ECM generates commands to operate various control relays and actuators, thereby adjusting the engine's operating parameters and ensuring maximum efficiency with minimal fuel consumption. The layout of the electronic control modules for various vehicle systems is shown in the illustrationFront Door Control Module Installation Details.
Reading the OBD II processor memory (ECM) is done with a special scanner connected to the 16-pin diagnostic connector for reading the database (DLC). The same scanner is used to clear the processor memory. It would be reasonable to entrust the procedures for reading DTC codes and clearing the ECM memory to car service specialists.
Note: On some models, reading of fault codes (DTC) stored in the ECM memory can in principle be performed using the auxiliary LED, as well as by codes displayed on the automatic air conditioning display.
The DLC connector is located on the left side under the vehicle's instrument panel
Identifying the 16-Pin Data Link Connector (DLC) Terminals
1 -; 2 -; 3 - TNA signal; 4 - Connection to housing, terminal 31; 5 - Housing - signal output, terminal 31; 6 - CAN data bus high level; 7 - Engine Electronics (ME); 8 - Power supply, terminal 87; 9 - Traction Control 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 - Positive battery via fuse. Live at any ignition switch position, terminal 30
Information about diagnostic devices
Connecting a multimeter to the engine control unit connectors using an auxiliary splitter
The proper functioning of injection system components and exhaust gas toxicity reduction systems is checked using a universal digital meter (multimeter). Using a digital meter is preferable for several reasons. Firstly, it is quite difficult to measure the value of an analog meter (sometimes - impossible), determine the result of the reading with an accuracy of up to 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 the digital multimeter has a fairly high impedance (the internal resistance of the device is 10 mOhm). Since the voltmeter is connected to the circuit being tested in parallel, the accuracy of the measurement is higher, the smaller the current that passes through the device itself. This factor is not significant when measuring relatively high voltage values (9÷12 V), but it becomes decisive when diagnosing 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. In this case, with the engine turned off, running, or while the car is moving, the parameters of the signals at the terminals of the splitter are measured, from which a conclusion is made about possible defects.
Special diagnostic scanners or testers with a specific cartridge can be used to diagnose electronic systems of the engine, automatic transmission, ABS, SRS and others (if provided), a universal cable and connector. In addition, for this purpose, you can use an expensive specialized automotive diagnostic computer, specially designed for full diagnostics of most systems of modern cars (for example, ADC2000 by 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 the installed OBD II browser program.
Some scanners, in addition to the usual diagnostic operations, allow, when connected to a personal computer, to print out the basic diagrams of electrical equipment stored in the control unit memory (if any are included), program the anti-theft system, observe signals in the car circuits in real time.
Read diagnostic codes and clear processor memory
Wiring diagram of the STAR DIAGNOSIS (0100) reader to the DLC diagnostic connector (X11/4)
Reading DTC codes and clearing the processor memory of the on-board diagnostic system is carried out using the proprietary STAR DIAGNOSIS (0100) scanner, connected to the 38-pin DLC connector (X11/4) of the vehicle.
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 follow the instructions displayed on the screen depending on the task at hand (reading codes, clearing memory, etc.).
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