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Diagnostics of systems of electronic control and diagnostic equipment
The composition of the OBD system includes several diagnostic devices making monitoring of separate parametres 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 also produces verification of sensors and actuators, controls the cycles of vehicle maintenance, allows storing even briefly encountered in the process crashes and cleaning of the storage unit.
All are described in this manual model equipped with second-generation on-board diagnostics (OBD II). The main element of the system is the onboard processor, more often called the Electronic Control Module (ECM), a control unit the operation of the power unit (PCM). PCM is the brain of the engine management system. Input data supplied to unit of information from various sensors and other electronic components (circuit breakers, relays, etc.). Based on the analysis coming from information gauges the data and in accordance with laid down in the memory of the processor basic parameters, RSM develops commands on operation of various control relays and actuators, thereby effecting adjustment of the operating parameters of the engine and providing peak efficiency of its return at the minimum fuel consumption . Reading the data processor memory OBD-II is made using a special scanner connected to a 16- or 38-pin diagnostic socket reader Database (DLC), located inside the vehicle.
 | Basically, reading written down in memory of the self-diagnosis fault codes possible on some models, with the help of auxiliary LEDs, as well as the codes displayed on the display automatic SQ. |
Data on diagnostic devices
Check of serviceability of functioning of components of systems of injection and emission control is performed with a universal digital meter (DMM). Using a digital meter is preferred for several reasons. First, on analogue devices it is rather difficult (sometimes impossible) to determine the result of readings with an accuracy of hundredths and thousandths, while at inspection of the contours including in the structure electronic components, such accuracy takes on special significance. The second, no less important reason is the fact that the internal contour of a digital multimeter, has high enough impedance (internal resistance of the device is 10 megohms). As the voltmeter is connected to a checked chain in parallel, accuracy of measurement is higher, the less current will flow through the device itself. This factor is not significant when measuring relatively high voltages (9 - 12), but becomes the determining the diagnosis of issuing low voltage components, such as, for example, lambda probe, where we are talking about the measurement of a volt.
Parallel monitoring of signal parameters, resistance and voltage in all control circuits possible using a splitter connected in series to the engine control unit connector. Thus on the switched off, the engine is running or while the vehicle is moving, the signal parameters are measured at the terminals of the hub, from which a conclusion about possible defects.
For the diagnosis of the electronic systems of the engine, automatic transmission, ABS, SRS and others can use special diagnostic scanners or testers with a certain cartridge (if provided), a universal cable and connector. In addition, for this purpose, you can use expensive specialized automobile diagnostic computer specially developed for full diagnostics of the majority of systems of modern cars (for example, ADC2000 firms Launch HiTech). Also, for this purpose can apply scanners and specialized diagnostic analyzers, such as FDS 2000, Bosch FSA 560, KTS 500 (0684400500) or a conventional personal computer with a special controller, cable (for example, set 1687001439) and the installed program browser OBD II.
Some scanners, besides usual operations of diagnostics, allow, when connecting to a personal computer to print data stored in the control unit electrical circuit diagrams (if incorporated), anti-theft system to program, monitor signals in the circuits of the vehicle in real time.
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