On-Board Diagnostics (OBD) System
1. The models described in this Manual are equipped with the European On-Board Diagnostics (EOBD) system.
2. Reading OBD system data and clearing the processor memory is performed using special diagnostic equipment connected to the diagnostic connector (DLC) - see the accompanying illustration. It would be reasonable to entrust the procedures for reading/erasing DTC codes and clearing the ECM memory to service station specialists. The K-line diagnostics is used only for diagnosing the engine management system and DSG transmission (see illustration 1.1). Diagnostics of other control units is carried out via the CAN bus.
4.2 Connecting the diagnostic tool
Information about diagnostic devices
3. Checking the proper functioning of the injection system components and reducing exhaust toxicity is performed using a universal digital meter (multimeter). There are several reasons why using a digital meter is preferable. Firstly, it is quite difficult (sometimes impossible) to determine the reading result with an accuracy of hundredths and thousandths using analog devices, while such accuracy is of particular importance when examining circuits that include electronic components. The second, no less important, reason is the fact that the internal circuit of a digital multimeter has a fairly high impedance. Since the voltmeter is connected to the circuit being tested in parallel, the lower the current that passes through the device itself, the higher the measurement accuracy. 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.
4. 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. In this case, with the engine off or running, or while the car is moving, the signal parameters are measured at the terminals of the splitter, from which a conclusion is made about possible defects.
5. For diagnostics of electronic systems, it is recommended to use the VAS5051 B diagnostic complex, or the VAS5052 or VAS5053 diagnostic tester. In addition, for this purpose, you can use a specialized automotive diagnostic computer, specially designed for complete diagnostics of most systems of modern cars (for example, ADC2000 from Launch HiTech). For this purpose, you can also use scanners and specialized diagnostic analyzers, for example, FDS 2000, Bosch FSA 560 (www.bosch.de) or a regular personal computer with a special adapter, cable and an installed OBD II browser program.
Note: A free version of the OBD II browser can also be "downloaded" from the website of the authors of this Guide: http://arus.spb.ru.
6. 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 memory of the control unit (if any are included), program the anti-theft system, monitor signals in the car circuits in real time.