E30 series BMW 3

since 1983-1994 of release

Repair and car operation

+ 1. Maintenance instruction
+ 2. Maintenance
+ 3. Engine
+ 4. Cooling system
+ 5. Heating and ventilation
+ 6. Fuel system
+ 7. Exhaust system
+ 8. Transmissions
+ 9. Coupling
- 10. Brake system
   10.2. Specifications
   10.3. Anti-blocking system (ABS)
   10.4. Blocks of disk brakes
   10.5. Support of a disk brake
   10.6. Brake disk
   10.7. Blocks of drum-type brakes
   10.8. Main cylinder of brakes
   10.9. Vacuum amplifier of brakes
   10.10. Cable (ы) hand brake
   10.11. Adjustment of the hand brake
   10.12. Mechanism of the hand brake
   10.13. Brake pedal
   10.14. Switch of a signal of braking
   10.15. Hoses and lines of a hydraulic actuator of brakes
   10.16. Air removal from a hydraulic actuator of brakes
+ 11. Running gear
+ 12. Body
+ 13. Electric equipment
+ 14. Good advice


10.3. Anti-blocking system (ABS)


Anti-blocking system of considered cars

1. Control unit hydraulics
2. Control lamp
3. Main cylinder
4. Electronic control unit
5. Wheel cylinder
6. Sensor of speed of rotation of a wheel

Arrangement of knots and units of anti-blocking system on the car

1. Control lamp
2. Control unit hydraulics
3. Hydraulic actuator highway
4. Wheel cylinder
5. Sensor cogwheel
6. Main cylinder
7. Sensor of speed of rotation of a wheel
8. Control unit

The ABS system is intended for increase of controllability and stability of the car at sharp braking at the expense of pressure control in the line of a hydraulic actuator of each wheel. At operation of devices of system during sharp braking of a wheel растормаживаются. ABS consists of sensors of speed of rotation of wheels, the electronic control unit and the control unit hydraulics. Till 1985 on cars 3 sensors of speed – on forward wheels and 1 sensor on a back axis were established. Since 1985 4 sensors – on one on a wheel are established. Signals from sensors are compared in the control unit to a preset value on the basis of what the blocked wheel is defined. The control unit develops a signal on the control unit hydraulics therefore pressure in a contour of a wheel falls, causing its unblocking.

To malfunction in system points fire of a control lamp of "ABS" on a guard of devices. Sometimes malfunction is established by external survey of knots of system. Attentively examine conducting and connections on each wheel. If conducting of the sensor of speed is damaged, the sensor replace (the sensor is executed at the same time with conducting).


It is forbidden to repair system conducting as its electric resistance can be broken that will lead to failures in system work. At any damage of a wire are subject to replacement.

Diagnostics and repair

If "ABS" lamp on the dashboard lights up, execute the following:

1. Check level of brake liquid in a tank

2. Check fastenings of sockets of conducting to the electronic block

3. Check safety locks

4. Check reliability and absence damage on all connections of conducting

If as a result malfunction is not eliminated, address in car-care center.