|
|
 printable version
Anti-lock braking system (ABS) - the general information and codes of malfunctions
Hydraulic diagram of anti-lock brakes
 | 1 - The right front wheel
2 - brake caliper
3 - GTZ
4 - Assembling the brake servo
5 - The left front wheel
6 - Second part of the circuit
7 - Primary part of the circuit
8 - Left front control valve
9 - Second-sensitive valve
10 - The primary sensing valve
11 - Right front control valve
12 - Second drain valve
13 - The primary drain valve
14 - Right front solenoid valve
15 - control valve | 16 - Right Rear Solenoid Valve
17 - accumulator
18 - Pump
19 - Pump
20 - Drive motor
21 - Tank
22 - Tank
23 - left front solenoid valve
24 - control valve
25 - Left Rear Solenoid Valve
26 - Right Rear Wheel
27 - brake caliper
28 - Load Sensing control valves
29 - The left back wheel |
general information
When the vehicle is equipped with a braking system of conventional type, sharp squeezing of a pedal of a foot brake leads to blocking of wheels. In this case violated grip tread and the road surface and the vehicle can go skid, losing control. Anti-lock brakes (ABS) prevents premature blocking of wheels, continuously controlling the speed of their rotation during braking by modulating the pressure of hydraulic fluid in each of the brake mechanisms.
 | ABS consists of two main subsystems: electric and hydraulic. The electrical part of the system consists of four wheel speed sensors, electronic control unit (ECU) and a set of connecting wiring. The hydraulic part includes the pressure modulator, supports of disk brake mechanisms, and interconnect these components hydraulic lines. |
The principle of the system is quite simple. Each of the wheels are equipped with individual speed sensor. The sensor consists of a rotor (rings evenly spaced around the perimeter of the teeth) and the sensor element in the form of a coil magnetized. The sensing element detects the passage of a tooth of the rotor, and converts the received information into electrical signals continuously transmitted to ECU ABS. The results of processing the input signals the control unit receives information on the relative speed of each wheel. While all four wheels rotate with identical frequency, ABS stays in a passive state. As soon as any of wheels starts to be blocked, ECU detects the change of the input signal and generates a command to the operation of the modulator instantly relieve the pressure of the hydraulic fluid in the brake mechanism on the wheel. As soon as the normal rotation of the wheel is reduced, the CPU suspends the operation of the modulator.
In fact, the scheme of functioning ABS is much harder than it might seem, therefore, the drafters of the present Management do not recommend to owners of cars to make attempt of independent performance of repair system. In case of problems will be most reasonable to apply to the service specialist. The illustration is for reference shows a flow chart explaining the operation of the hydraulic ABS.
Components of ABS
The modulator pressure
The modulator consists of a hydraulic pump by-wire and three-solenoid valve switches (two left and right front and rear). The electric pump supplies the hydraulic fluid in the reservoir and modulator, which controls the process of change of pressure in the brake circuits. The pump is placed in a common housing with the assembly of the modulator. Solenoid valves Switches act as actuators, actually providing the required modulation of the pressure in the hydraulic path of brake system during operation ABS.
Wheel sensors
Special sensors, which are equipped with wheels of a vehicle, when passing by the sensing elements of their teeth rotating rotors generate the comb of electric pulses. The analog amplitude signal corresponding parameters supplied to the control unit (ECU) ABS, which converts it to a digital form and by analyzing the received information determines the speed of each wheel.
The front wheel sensors are mounted on the steering knuckle in the vicinity of the assembly pressed into the outer CV joints rotors.
Sensors rear wheels pribolcheny to the holders of the hub assemblies, while the rotors are built into the hub.
The electronic control unit (ECU) ABS
The electronic control unit, often referred to as a processor installed in the luggage compartment of the car (models 1993 and 1994 vol.), Or under the front driver's door sill trim (models from 1995 vol.). ECU, playing the role of a think-tank system takes coming from the speed sensors on the basis of the information and its analysis provides modulation control pressure in the hydraulic path of brake each wheel, preventing premature blocking. Processor continues to function in the normal operation of the vehicle is constantly monitoring the serviceability of a condition of components ABS.
Each time the engine is started there is a brief switch control lamp ABS in the dashboard of the car. The first survey of the state of the diagnostic components produced ABS control unit when the vehicle speed reaches 6.4 km / h (4 miles / h). survey may be accompanied by mild mechanical sounds that should not be given importance. In case of problems ECU ensures the inclusion of a control lamp ABS, both in memory of the processor corresponding fault code is entered, the reading of which in the future will determine the source of the fault.
Diagnosis and reconditioning
In identifying the problems in the system processor in the instrument panel lights up and stays on control lamp ABS. Troubleshooting anti-lock system is one fairly complex procedures and composers of the present Management do not recommend to make it at home. Nevertheless, it is possible to identify a number of simple tests that can be quite successfully produced its own car owner and allow to determine the cause of failure (see. Below).
Models 1993 and 1994 Vol.
a) Accelerate the vehicle to 32 km / h (20 miles / h) and hold this movement speed for at least one minute;
b) Stop the movement, but does not shut off the engine;
c) Open the luggage compartment and count the number of flashes mounted in the assembly of the control unit (ECU) control lamp ABS on the LED. If you have a processor memory fault code warning lamp will issue a series of continuous flashes with pauses of 5-10 seconds between them;
d) Explanation of displayed warning lamp codes provided in the explanatory chart (See below.).
e) Stop the engine.
Models from 1995 MY.
a) Accelerate the vehicle to 32 km / h (20 miles / h) and hold this movement speed for at least one minute;
b) Stop traffic and switch off the engine;
c) Ground terminal L diagnostic socket DLC;
d) Turn the ignition switch to ON;
e) After 3.6 seconds the ABS warning lamp starts to flash memory stored in two-digit processor system DTCs. Each digit of the code is defined by a series of short (in 0.4 seconds) lamp flashes separated by a pause of the same length, the second digit is separated from the first pause of 1.6 seconds. The moment marked the beginning of the reading of the issuance of the code 12 (one flash, a pause, two flashes). Then, again followed by a long (3.6 second) pause, after which the light begins to flash stored in the control unit codes.
f) Explanation of displayed warning lamp codes provided in the explanatory chart (See below.).
The reason for introducing code into the memory of the processor can be the most simple fault - first of all make the following checks:
a) Make sure all hydraulic fluid level in the reservoir GTZ;
b) Check the condition of the respective contact connections electrical circuits;
c) Check fuses;
d) Check the state of the brake system (see chap. Adjustment and routine maintenance);
e) Check the condition of brake pads;
f) Check the state of the brake pedal.
Clear memory of the processor ABS
To clear the memory of the processor, disconnect grounding terminals L connector DLC, - the ABS warning lamp must remain switched on. Perform three successive ground terminals L within 12.5 seconds. Each subsequent grounding should last for at least 1 second longer than the previous one - the control lamp should switch off:
a) If the warning lamp manufactured after manipulation grounding terminal remains on, drive to a repair shop for more detailed diagnostics and necessary reconditioning ABS;
b) If the light goes out, take a short trip by car, for at least 1 minute of moving at a speed of 32 km / h (20 miles / h) and make sure that does not happen again operation of the lamp. If the lamp is switched on again, drive to a repair shop for diagnostics and regenerative repair of ABS.
Map of codes of malfunctions ABS models 1993 and 1994 Vol.
| The number of flashes, odiodom | Presumably the failed node issued or light circuit | | 1 | Solenoid valve pressure switch in the path of the left front wheel | | 2 | Solenoid valve pressure switch in the path of the right front wheel | | 3 | Solenoid valve pressure switch in the path of the right rear wheel | | 4 | Solenoid valve pressure switch in the path of the left rear wheel | | 5 | Speed sensor Left Front Wheel | | 6 | Speed sensor front right wheel | | 7 | Speed sensor rear right wheel | | 8 | Speed sensor rear left wheel | | 9 | The electric motor and the relay switch it on | | 10 | The relay of inclusion of the solenoid valve | | 16 (or lit) | ECU | | ABS warning lamp is turned on, the LED is off | Grounding or ECU power supply circuit |
Grounding or ECU power supply circuit
| Number of flashes issued LED | Presumably the failed node or a loop | | 12 | The start code reading | | 16 | Circuit stoplights | | 18 | Rotor wheel sensor | | 21 | Open circuit speed sensor right front wheel | | 22 | Short circuit speed sensor right front wheel | | 25 | Open circuit speed sensor Left Front Wheel | | 26 | Short circuit speed sensor Left Front Wheel | | 31 | Open circuit speed sensor Right Rear Wheel | | 32 | Short circuit speed sensor Right Rear Wheel | | 35 | Open circuit speed sensor Left Rear Wheel | | 36 | Short circuit speed sensor Left Rear Wheel | | 41 | Exhaust valve switch right front brake ABS modulator | | 42 | The inlet valve switch right front brake ABS modulator | | 45 | Exhaust valve switch the left front brake ABS modulator | | 46 | The inlet valve switch the left front brake ABS modulator | | 51 | Exhaust valve switch right rear brake ABS modulator | | 52 | The inlet valve switch right rear brake ABS modulator | | 55 | Exhaust valve switch left rear brake ABS modulator | | 56 | The inlet valve switch left rear brake ABS modulator | | 57 | Violation of the supply voltage | | 61 | The electric motor of the modulator, or switch its inclusion | | 63 | Infringement in a chain of the relay of the solenoid valve | | 71 | ECU | | 81 | Engine speed sensor | | 85 | ECU ABS | | 87 | The engine operates in an emergency mode, | | 92 | The procedure for starting the transfer is not completed LAN | | 94 | Admission is continued after completion of the transfer LAN | | 96 | LAN is in tracking mode | | 98 | Disclaimer transmission system LAN |
| The warning lamp stays on after the ignition | The circuit power supply to the ECU;
Chain control lamp;
The ECU or its wiring connector;
Sticking relay electromagnetic riveting;
The circuit power supply to the relay coil of the solenoid valve | | SLIP indicator stays on after the engine is started (1999) | The circuit power supply to the ECU;
Chain control lamp;
The ECU or its wiring connector;
Sticking relay electromagnetic riveting;
The circuit power supply to the relay coil of the solenoid valve | | The indicator lamp remains lit during the self-test mode | ECU | | The indicator lamp is not activated when the ignition (1995 ÷ 1998) | Fuse;
The indicator lamp;
ECU | | SLIP indicator does not turn on when the engine is running (1999) | Fuse;
The indicator lamp;
ECU | | The warning lamp does not work in a self-diagnosis | ECU |
|
|
