7.2.3. System of onboard self-diagnostics of OBD - the general information
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The material given below has only descriptive character and is not attached to any concrete brand or model of the car. |
Data on diagnostic units
Check of serviceability of functioning of components of systems of injection and decrease in toxicity of the fulfilled gases is made by means of the universal digital measuring instrument (multimeter). Use of the digital measuring instrument is preferable for several reasons. First, on analog devices it is rather difficult (sometimes, it is impossible), to define result of the indication to within the 100-th and thousand shares while at inspection of the contours including electronic components in the structure, such accuracy is of particular importance. The second, not less important, the fact that the internal contour of a digital multimeter, has rather high impedance is the reason (internal resistance of the device makes 10 million Ohms). As the voltmeter is connected to the checked chain in parallel, the accuracy of measurement of subjects is higher, than smaller parasitic current will pass through actually device. This factor is not essential at measurement of rather high values of tension (9 ÷ 12 V), however becomes defining at diagnostics of the elements giving low-voltage signals, such as, for example, lambda probe where it is about measurement of shares of volt.
The most convenient devices for diagnostics of control systems of the engine of modern models of cars are manual readers of skanerny type. Scanners of the first generation serve for reading of codes of malfunctions of the OBD-I systems. Before application the reader should be checked for compliance of model and year of release of the checked car. Some scanners are multipurpose at the expense of a possibility of change of a cartridge depending on model of the diagnosed car (Ford, GM, Chrysler, etc.), others are tied to requirements of the regional authorities and intended for use in certain regions of the world (Europe, Asia, the USA, etc.).
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Recently, at diagnostics of control systems of the engine of modern cars such reading-out devices as Actron Scantool or AutoXray XP240 hand scanners became absolutely irreplaceable |
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The diagnostic New Generation Star (NGS) scanner (also the scanners FDS 2000, Bosch FSA 560 and KTS 500 [0 684 400 500] were widely used) |
With introduction to production to meeting requirements of the last legislations for environmental protection of system of onboard diagnostics of the second generation (OBD-II) readers of a special design began to be issued. Some producers marketed the scanners intended for use by amateur mechanics in house conditions, - ask in shops of automobile accessories. One more very convenient diagnostic unit is the expensive specialized diagnostic ADC2000 computer of Launch HiTech), or the ordinary personal computer in a set with a special cable and the adapter (a set 1 687 001 439). Some scanners besides usual diagnostic operations allow at connection to the personal computer to unpack stored in memory of the module of management schematic diagrams of electric equipment (if those are put), to program anticreeping system, to observe signals in safety lock chains in real time.
The adapter for coordination of diagnostic lines K and L from computer SOM ports
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The free version of a browser of OBD II can be downloaded from the website of authors of the present manual http://arus.spb.ru. |
In principle, reading of the codes of malfunctions which are written down in memory of system of self-diagnostics can be made by means of a control lamp of refusals of MIL and a wire crossing point established between concrete plugs of the 16-contact diagnostic socket.
General description of the OBD system
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At the modules equipped with the OBD II system on installed under a cowl Schild there has to be a record "OBD II compliant", and the diagnostic DLC socket has to be 16-contact. As a rule, the OBD II system surely equips the models intended for the North American market since 1996 of release, and also the European models, since 2000 release. |
Several diagnostic devices making monitoring of separate parameters of systems of decrease in toxicity and fixing the revealed refusals in memory of the onboard processor in the form of individual codes of malfunctions are a part of the OBD system. The system makes also check of sensors and actuation mechanisms, controls operational cycles of the vehicle, provides a possibility of freezing of parameters and cleaning of the block of memory.
All models described in the present manual are equipped with system of onboard diagnostics of the second generation (OBD-II). A basic element of system is the onboard processor more often called by the electronic module of management (ECM). ECM is a brain of a control system of the engine. Basic data arrive on the module from various information sensors and other electronic components (switches, the relay, etc.). On the basis of the analysis of the data arriving from information sensors and according to the basic parameters put in the processor memory, ECM develops commands for operation of various operating relays and actuation mechanisms, carrying out thereby adjustment of working parameters of the engine and providing maximum efficiency of its return at the minimum fuel consumption. Data read-out of the processor memory of OBD-II is made by means of the special scanner connected to the 16-contact diagnostic socket of reading of the database (DLC) located under a decorative cover on the central console ahead of the lever of the drive of the parking brake.
The diagnostic socket of the OBD II system, - at connection use the standard OBD-II J1962 cable
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In principle, reading of the codes of malfunctions which are written down in memory of system of self-diagnostics can be made by means of the wire crossing point established between concrete plugs of the 16-contact diagnostic socket (address illustrations). |
Special guarantee certificates with the extended validity extend to service of components of control systems of engine/decrease in toxicity of the fulfilled gases. It is not necessary to make attempts of independent performance of failure diagnostics of ECM or replacement of components of system, to an exit of terms of these obligations, - address specialists of company car repair shops of the Opel company.
Information sensors (depending on a car complete set)
Oxygen sensors (lambda probes) - the Sensor develops a signal which amplitude depends on a difference of content of oxygen (O2) in the fulfilled gases of the engine and external air.
Sensor of provision of a bent shaft (ICR) - The sensor informs ECM on the provision of a bent shaft and turns of the engine. This information is used by the processor during the determining of the moments of injection of fuel and installation of a corner of an advancing of ignition.
Sensor of position of pistons (CYP) - On the basis of the analysis of the signals of ECM arriving from the sensor calculates position of the piston of the first cylinder and uses this information when determining the moments and the sequence of injection of fuel in engine combustion chambers.
BMT (TDC) sensor - The signals developed by the sensor are used by ECM when determining installations of a corner of an advancing of ignition at engine launch.
Sensor of temperature of cooling liquid of the engine (EST) - On the basis of information of ESM/arriving from the sensor carries out necessary corrections of composition of air-fuel mix and a corner of an advancing of ignition, and also controls work of the EGR system.
The sensor of temperature of the soaked-up air (IAT) - ECM uses information arriving from the IAT sensor at corrections of a stream of fuel, installations of a corner of an advancing of ignition and management of functioning of the EGR system.
Sensor of provision of a butterfly valve (TPS) - The sensor is located on the case of a throttle and connected to an axis of a butterfly valve. Determines the angle of opening of a butterfly valve (is operated by the driver from the accelerator pedal) by amplitude of the given TPS of a signal of ECM and as appropriate corrects supply of fuel to inlet ports of combustion chambers. The failure of the sensor, or weakening of its fastening leads to interruptions of injection and violations of stability of turns of idling.
The sensor of absolute pressure in the pipeline (MAR) - The sensor controls the depression depth variations in the inlet pipeline connected with changes of turns of a bent shaft and load of the engine and will transform the obtained information to an amplitude signal. ECM uses information delivered by the MAR and IAT sensors at thin corrections of supply of fuel.
Barometric sensor of pressure (BARO) - The sensor develops the amplitude signal proportional to changes of atmospheric pressure which is used by ECM when determining duration of the moments of injection of fuel. The sensor is built in the ECM module and is not subject to service in an individual order.
Sensor of a detonation (KS) - The sensor reacts to change of level of the vibrations connected with detonations in the engine. On the basis of information of ECM arriving from the sensor carries out the corresponding correction of a corner of an advancing of ignition.
Sensor of speed of the movement of the car (VSS) - As appears from its name, the sensor informs the processor on the current speed of the movement of the car.
Sensor of size of opening of the EGR valve - The sensor notifies ECM on EGR valve plunger shift size. The obtained information is used then the processor at management of functioning of system of recirculation of the fulfilled gases.
Pressure sensor in the fuel tank - the Sensor is a component of system of catching of fuel evaporations (EVAP) and the dlyaotslezhivaniya of pressure of vapors of gasoline serves in a tank. On the basis of information of ECM arriving from the sensor issues commands for operation of electromagnetic valves of a purge of system.
Sensor switch of pressure of system of hydrostrengthening of a wheel (PSP) - On the basis of information of ECM arriving from the PSP sensor switch provides increase in turns of idling due to operation of the sensor of system of stabilization of turns of idling (IAC) for the purpose of compensation of the increasing loads of the engine connected with functioning of the steering hydraulic booster at commission of maneuvers.
Transmission sensors - In addition to the data arriving from VSS, ECM obtains also information from the sensors placed in the transmission, or connected to it. Are among such sensors: (a) RPM meter of a secondary (radical) shaft and (b) RPM meter of an intermediate shaft.
The sensor switch of management of inclusion of a clutch coupling of the conditioner of air - When giving power supply from the battery to the electromagnetic valve of the K/V compressor the corresponding information signal arrives on ECM which regards it as the evidence of increase of load of the engine and as appropriate corrects turns of its idling.
Actuation mechanisms
The relay of the fuel pump - ECM makes activation of the relay of the fuel pump when turning the ignition key in situation II or III. At inclusion of ignition activation of the relay provides rise in pressure in a power supply system. More detailed information on the main relay is provided in the Head of the Power supply system, release and decrease in toxicity of the fulfilled gases.
The fuel injector(s) - ECM provides individual inclusion of each of injectors according to an established order of ignition. Besides, the module controls duration of opening of injectors determined by the width of the operating impulse measured in milliseconds and defining amount of the fuel injected into the cylinder. More detailed information on the principle of functioning of system of injection, replacement and service of injectors is provided in the Head of the Power supply system, release and decrease in toxicity of the fulfilled gases.
Module of management of ignition (ICM) - The module operates functioning of the coil of ignition, defining the required basic advancing on the basis of the developed ECM teams.
Valve of stabilization of turns of idling (IAC) - The IAC Valve carries out a dosage of amount of the air bypassed bypassing a butterfly valve when the last is closed or holds idling position. ECM operates opening of the valve and formation of the resulting air stream.
The electromagnetic valve of a purge of a coal adsorber - the Valve is a component of system of catching of fuel evaporations (EVAP) and, working at the command of ECM, makes production of the fuel vapors which accumulated in an adsorber in the inlet pipeline for the purpose of burning them in the course of normal functioning of the engine.
The electromagnet of management of a purge of a coal adsorber - the Electromagnet is used by ECM when checking by the OBD-II system of serviceability of functioning of the EVAP system.
Reading of codes of malfunctions and cleaning of the processor memory
At detection of the malfunction repeating in a row in spirit trips, ECM issues the command for inclusion of the control lamp which is built in in an instrument guard "Check the engine", called also by the indicator of refusals (MIL). At the same time ECM switches to emergency operation. The lamp will continue to burn until memory of system of self-diagnostics is not cleared of the codes of the revealed malfunctions brought in it.
Reading of codes by means of the scanner
Reading of codes of malfunctions is made by connection of the special reader to the 16-contact diagnostic DLC socket, - act according to indications of the menu of the device.
Reading of codes by means of a control lamp of refusals of MIL
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PERFORMANCE ORDER |
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Information contents of categories of a 5-digit code of a type of P0380
Categories of a code of a look P 0 3 8 0 have the following value (from left to right):
1 category | |
| P | power unit |
| B | body |
| With | chassis |
| U | communication tires of data exchange of control systems |
2 category | Code source |
| 0 | standard SAE |
| 1 | expanded - set by the producer |
3 category | System |
| 0 | system in general |
| 1 | air admixture |
| 2 | fuel injection |
| 3 | system of ignition or admissions of ignition |
| 4 | additional control of release |
| 5 | speed of the car and management х.х. |
| 6 |
entrance and output signals of the control unit |
| 7 | transmission |
4,5 categories |
Serial number of malfunction of a component or chain (00-99) |
Cleaning of memory of OBD
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PERFORMANCE ORDER |
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Cleaning of memory of OBD by a detachment of a negative wire from the battery, is accompanied by removal of adjusting parameters of the engine and violation of stability of its turns for a short time after primary start, and also by deleting of settings of hours and the radio receiver. |
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If the stereosystem established on the car is equipped with a security code before disconnecting the battery make sure that you have the correct combination for input of the audio system in action! |
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In order to avoid damage of ESM its shutdown and connection should be made only at the switched-off ignition! |
The code which is written down in memory is removed automatically if the corresponding malfunction does not appear during 20 following in a row one after another of starts of the engine (the quantity of turns has to be not lower than 450 in a minute).
Track that memory of system was cleared before installation on the engine of new components of systems of decrease in toxicity of the fulfilled gases. If before start of system after replacement of the failed information sensor not to make cleaning of memory of refusals, ECM will bring in it a new code of malfunction. Cleaning of memory allows the processor to make change-over on new parameters. At the same time the first 15-20 minutes after primary start of the engine before the end of adaptation of ECM, some violation of stability of its turns can take place.