14.14.2. System of onboard diagnostics (OBD) principle of functioning and codes of malfunctions
Data on diagnostic units
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- 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) (see an accompanying illustration). 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 megohms). 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, oxygen sensor where it is about measurement of shares of volt.
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- The most convenient devices for diagnostics of control systems of the engine of cars are manual readers of skanerny type (see an accompanying illustration). 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.). Recently, at diagnostics of control systems of the engine of modern cars such reading-out devices as hand scanners of type, for example, of Actron Scantool or AutoXray XP240 became absolutely irreplaceable
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General description of the OBD system
All models described in the present manual are equipped with system of onboard diagnostics (OBD).
Basic element of system is the onboard processor more often called by the electronic module of management of functioning of the power unit (RSM). RSM 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, RSM 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.
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 RSM or replacement of components of system, to an exit of terms of these obligations, - address specialists of company car repair shops of the Nissan company.
Information sensors
Sensor of position of the camshaft (SMR) - The sensor develops information signals on the basis of which analysis RSM defines the current phase of gas distribution and frequency of rotation of the engine, using the obtained information at management of the sequence of injection and ignition of air-fuel mix in combustion chambers.
Sensor(s) of provision of a bent shaft (ICR) - On latest models two sensors of ICR whereas on earlier models only one such sensor was used are used. The signals arriving from sensors are used by RSM as turns of the engine and provisions of VMT of the piston of each of cylinders, basic at definition. On the basis of the obtained information of RSM exercises control of the sequence of injection and ignition of air-fuel mix in combustion chambers. In the OBD-II systems the signals developed by sensors of ICR are used also at failure diagnostics of the power unit.
Sensor of temperature of cooling liquid of the engine (EST) - On the basis of information of RSM 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.
EGR temperature sensor - Information arriving from the sensor is used when determining intensity of recirculation of the fulfilled gases to the reception highway of the engine.
The fuel temperature sensor - RSM uses information issued by the sensor at failure diagnostics of components of system.
The sensor of temperature of the soaked-up air (IAT) - RSM uses information arriving from the IAT sensor at adjustments of parameters of injection, installations of a corner of an advancing of ignition and at management of functioning of the EGR system.
The detonation sensor - the Sensor represents the piezoelement reacting to change of intensity of vibrations of the engine. On the basis of the analysis of information of RSM arriving from the sensor carries out corrections of a corner of an advancing of ignition for the purpose of timely elimination of the detonation of the air-fuel mix fraught with premature wear of internal components of the engine arising in combustion chambers.
The sensor of absolute pressure in the pipeline (MAR) (late models) - 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. Information arriving from the sensor is used by the module of management at failure diagnostics of the engine.
Measuring instrument of mass of air (MAF) - The MAF Sensor determines volume and weight parameters of the air stream coming to the inlet pipeline. As a sensitive element in the sensor filament is used. RSM uses information delivered by the MAR and IAT sensors at thin adjustments of parameters of injection.
The oxygen sensor (a lambda - the probe) - the Sensor develops a signal which amplitude depends on a ratio of amount of oxygen (O2) which is contained in the fulfilled gases of the engine and external air. On the basis of information of RSM arriving from the sensor determines parameters of air-fuel mix, in due time carrying out its enrichment or impoverishment.
Sensor switch of pressure of working liquid of system of hydrostrengthening of a wheel (PSP) - On the basis of information of RSM arriving from the PSP sensor switch provides increase in turns of idling (due to operation of the IAC valve) for the purpose of compensation of the increasing loads of the engine connected with functioning of the steering hydraulic booster at commission of maneuvers.
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 RSM 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.
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.
Other, controlled RSM parameters - Besides given out by the listed above sensors on RSM also additional information on functioning of various knots and systems defining performance data of the engine arrives. To number other, systems and knots which control of functioning is exercised by RSM the following belongs:
- Air conditioning system;
- ABS;
- Rechargeable battery (output tension);
- EVAP system;
- Ignition switch;
- Sensor switch of permission of start;
- Grounding chains;
- Control system of functioning of transmission.
Actuation mechanisms
The relay of management of functioning of a clutch coupling To/in - RSM carries out shutdown of the K/V compressor during intensive acceleration.
Control lamp "Check the engine" - RSM makes inclusion of this control lamp at emergence of refusals of functioning of a control system of the engine.
The relay of management of functioning of fans of the cooling system - RSM exercises control of functioning of fans of the cooling system on the basis of the analysis of the signals arriving from the sensor of temperature of cooling liquid.
Vacuum electromagnetic valves of management of EGR - RSM operates extent of opening of the vacuum EGR valve via the special intermediate electromagnetic valve.
EGR valve - On the RSM late models exercises control of a stream of recirculation of the fulfilled gases via the electronic EGR valve.
The valve of a purge of a coal adsorber - This electromagnetic valve, working at the command of RSM, carries out a purge of a coal adsorber of the EVAP system, removing the fuel evaporations which accumulated in it to the inlet highway of the engine.
The electromagnetic valve of management of turns of bystry idling - This valve is used on latest models and serves for increase in turns of idling in cold weather. In fact this valve carries out a role of the air gate on carburetor models.
The forward support of a suspension bracket of the power unit - On the RSM some models controls also rigidity of a forward support of the engine depending on the speed of the movement of the car. Minimization of vibrations is carried out by the choice of one of two installations of a support.
Fuel injection injectors - RSM 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 Chapter 7.
The relay of the fuel pump - the Relay is activated by the module of management when turning the ignition key in situation START/RUN. At inclusion of ignition of the relay carries out giving of food on a gasoline pump which provides rise in pressure in a path of a power supply system of the car. More detailed information on location and the principle of functioning of the relay is provided in Chapters 5 and 31.
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. RSM operates opening of the valve and formation of the resulting air stream.
The heater of the oxygen sensor - Control of functioning of this device is exercised by RSM. The heater makes a bystry warming up of the l-probe up to the normal working temperature.
The power transistor - the Transistor carries out strengthening of a signal of the ignition developed by RSM and in the fullness of time makes instant grounding on the mass of primary contour of system of ignition that causes generation of VV of the signal given by the coil (Amy) directly on spark plugs in a secondary chain of system.
Electromagnet of management of functioning of the valve of power - On late models control of functioning of the valve of power is exercised by RSM by means of a special electromagnet.
Module of management of functioning of transmission (TSM) - TSM, being the module of management, separate of RSM, receives signals from various information sensors, such as VSS, the sensor switch of permission of start, the RPM meter of a shaft of the turbine, TPS, SMR, etc., and uses the accepted data when determining the moment of switching of transfer of AT demanded pressure in a path and the moment of blocking of the converter of rotation.
Reading of codes of malfunctions
At detection of the malfunction repeating in a row in spirit trips, RSM 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. The lamp will continue to burn until then, violation will not disappear, and will not be shown during three and more trips.
The control unit with one light-emitting diode
Include ignition. Peremknite contacts of the IGN and CHK socket and in 2 sec. remove a crossing point. Consider flashes of a lamp. The number of long flashes corresponds to the number of tens of code, quantity of short – to quantity of units. In need of memory cleaning you peremknit the above-stated contacts again and in 2 sec. remove a crossing point. Switch off ignition.
The control unit with red and green light-emitting diodes
For reading of codes of malfunctions it is necessary to provide access to RSM for the purpose of switching of the selector to highlighting of codes by means of diagnostic lamps / a control lamp "Check the engine". RSM should remove from the basic arm (without disconnecting an electrical wiring) and to work according to the instructions given below.
- Include ignition (without starting the engine). A control lamp "Check the engine" for dashboards has to remain included that confirms delivery of food on it from RSM and serviceability of the lamp.
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Violation of an order of the procedure described below can lead to casual cleaning of memory of RSM! |
- By means of the screw-driver turn the selector on RSM wall against the stop clockwise. There have to begin a simultaneous blinking both light-emitting diodes, -
after three gleams
turn the selector against the stop counterclockwise;
- Attentively watch functioning of diagnostic lamps. The red light-emitting diode serves for highlighting of tens of code of malfunction, units of a code are highlighted by the green diode. For example, the code 43 (TPS chain) will look as follows: four gleams of the red diode, then three gleams green. Highlighting of a code 55 testifies to lack of the violations revealed by system (see below the card of codes of malfunctions);
- At repeated inclusion of ignition, after its switching off in the course of reading of codes the system, automatically cancels results of the previous search and the procedure of reading it is necessary to begin anew.
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Start of the engine automatically blocks access to system of self-diagnostics. |
- If turn of the selector against the stop counterclockwise on point b) to make at the moment after:
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the 1st gleam
the check mode a lambda probe will join (both diodes burn). Start the engine. The system will make self-diagnostics and in case of lack of malfunctions the green light-emitting diode will begin to blink. The green light-emitting diode burns constantly – mix of a pereobednen. The green light-emitting diode does not burn – mix of a pereobogashchen. The red light-emitting diode lights up upon termination of self-diagnostics.
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the 2nd gleam
the mode of check of a contour of quality management of mix will join (the green diode burns, red does not burn). Start the engine. The system will make self-diagnostics and in case of lack of malfunctions the green light-emitting diode will begin to blink. The red light-emitting diode burns constantly – mix of a pereobednen. The red light-emitting diode does not burn – mix of a pereobogashchen. The red light-emitting diode blinks together with zaleny – mix is optimum.
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the 4th gleam
the mode of check of a contour of the sensor of provision of a butterfly valve/speed of the car will join (the red diode burns). Start the engine. The red light-emitting diode has to light up and die away by each pressing the accelerator pedal. At the movement of the car the green diode has to light up when speeding 19 km/h.
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the 5th gleam
the mode of dynamic check will join. Start the engine and, changing turns, watch diodes.
One flash of red – malfunction in a chain of the sensor of position of the crankshaft;
Two flashes of green – malfunction in a chain of the measuring instrument of an air stream;
Three flashes of red – malfunction in a chain of the fuel pump;
Four flashes of green – malfunction in a chain of system of ignition.
Stop the engine.
Cleaning of memory of ECM/PCM
After the violations revealed in the course of diagnostics are eliminated, it is necessary to clear memory of RSM of the codes of malfunctions which are written down in it.
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Cleaning of memory by a wire detachment from the battery leads also to deleting of basic parameters and violation of stability of turns of idling at first after start of the engine. |
- Consider the codes of malfunctions which are written down in memory of system;
- Wait not less than two seconds, then turn the selector on RSM wall against the stop clockwise, - light-emitting diodes have to begin to blink;
- After four gleams of diodes turn the selector against the stop counterclockwise;
- Switch off ignition.
List of codes of malfunctions of system of self-diagnostics
Number of a code |
Possible cause of failure |
11 |
Malfunction in a chain of the RPM meter of the engine/sensor of provision of a bent shaft
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12 |
Malfunction in a chain of the measuring instrument of an air stream of VAF/weight of MAF air |
13 |
Malfunction in a chain of the sensor of temperature of the eats cooling liquid |
14 |
Malfunction in a VSS car speed sensor chain |
21 |
Malfunction in an ignition signal chain |
22 |
Malfunction in a chain of the fuel pump |
23 |
Malfunction in a chain for the switch of a closed position of a butterfly valve |
24 |
Malfunction in a chain for the switch of completely open position of the throttle gate / provision "P" "N" AT |
25 |
Malfunction in a chain of the valve of additional IAC air |
26 |
Malfunction in a turbocompressor pressure sensor chain |
28 |
Overheat |
31 |
The conditioner air/lack of malfunctions (model without conditioner) / Violation of serviceability of functioning of RSM (engines GA16i, CA18DE) |
32 |
Malfunction in a starter signal chain |
33 |
Malfunction in a chain of the oxygen sensor |
34 |
Malfunction in a chain of the sensor of the detonation/sensor of provision of a butterfly valve (SR20Di engine) |
35 |
Malfunction in a chain of the temperature EGR sensor |
41 |
Malfunction in a chain of the sensor of temperature of the soaked-up IAT air |
42 |
Malfunction in a fuel temperature sensor chain |
43 |
Malfunction in a chain of the sensor of provision of a butterfly valve of TPS |
44 |
Lack of malfunctions |
45 |
Leaks in injection injectors |
51 |
Malfunction in a fuel injection signal chain |
54 |
Malfunction in a chain of a signal of automatic transmission of AT |
55 |
Lack of codes of malfunctions in memory of system |
Diagnostics of security systems
It is made on a control lamp of SRS on the control panel or by means of a diagnostic lamp.
Models with the pyrotechnic device of a tension of seat belts
By means of a diagnostic lamp
At the switched-off ignition you peremknit contacts of 7 and 11 diagnostic sockets through a lamp no more 3.3vt. Include ignition. If everything is all right the lamp goes out approximately in 6 sec. If the lamp blinks conducting of the device of pyrotechnic natyazhitel of belts or the control unit is perhaps damaged.
On a control lamp of SRS
At the switched-off ignition open a driver's door and include ignition. Make sure that the lamp burns and during 7 sec. of 5 times press the switch of a driver's door. In 2 sec. after blackout of a lamp it will begin delivery of the blinking codes.
Number of a code |
Possible cause of failure |
11 |
Damage of conducting of the sensor of blow in front. SRS control unit |
12 |
Damage of conducting of a safety cushion of the driver. SRS control unit |
13 |
Damage of conducting of the sensor of blow in front. SRS control unit |
17 |
Damage of conducting of the control unit of a security system of SRS |
18 |
Damage of conducting of the passenger airbag. SRS control unit |
19 |
Multiple defects of conducting, control unit, sensor of blow, safety cushion |
Diagnostics of system of anti-blocking of brakes
Start the engine and pass on the car with a speed of 30 km/h not less than 1 min. Switch off ignition and close a conclusion 4 diagnostic sockets on the case. Include ignition and consider codes on flashes of a control lamp of ABS. Do not press a brake pedal during testing.
Number of a code |
Possible cause of failure |
12 |
Beginning of delivery of codes. |
18 |
Wheel RPM meter rotor. |
21 |
Break in a chain of the RPM meter of the right forward wheel. |
22 |
Short circuit in a chain of the RPM meter of the right forward wheel. |
25 |
Break in a chain of the RPM meter of the left forward wheel. |
26 |
Short circuit in a chain of the RPM meter of the left forward wheel. |
31 |
Break in a chain of the RPM meter of the right back wheel. |
32 |
Short circuit in a chain of the RPM meter of the right back wheel. |
35 |
Break in a chain of the RPM meter of the left back wheel. |
36 |
Short circuit in a chain of the RPM meter of the left back wheel. |
41 |
Output э / magnetic valve of the right forward wheel. |
42 |
Entrance э / magnetic valve of the right forward wheel.
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45 |
Output э / magnetic valve of the left forward wheel. |
46 |
Entrance э / magnetic valve of the left forward wheel. |
51 |
Output э / magnetic valve of the right back wheel. |
52 |
Entrance э / magnetic valve of the right back wheel. |
55 |
Output э / magnetic valve of the left back wheel. |
56 |
Entrance э / magnetic valve of the left back wheel. |
57 |
Low voltage of food. |
61 |
Relay / hydraulic pump. |
63 |
System relay. |
71 |
Electronic control unit. |