BMW 3 Series E30

since 1983-1994 release

Repair and operation of the car

+ 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 brakes
   10.8. Main cylinder of brakes
   10.9. Vacuum amplifier of brakes
   10:10. Cable(s) of the emergency brake
   10:11. Adjustment of the emergency brake
   10:12. Mechanism of the emergency brake
   10:13. Brake pedal
   10:14. Braking signal switch
   10:15. Hoses and lines of a hydraulic actuator of brakes
   10:16. Removal of air from a hydraulic actuator of brakes
+ 11. Running gear
+ 12. Body
+ 13. Electric equipment
+ 14. Useful tips


10.3. Anti-blocking system (ABS)


Anti-blocking system of the considered cars

1. Control unit of 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 of hydraulics
3. Highway of a hydraulic actuator
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 in controllability and stability of the car at sharp braking due to control of pressure in the line of a hydraulic actuator of each wheel. At operation of devices of system during sharp braking of a wheel rastormazhivatsya. ABS consists of sensors of speed of rotation of wheels, an electronic control unit and the control unit of hydraulics. Till 1985 on cars 3 sensors of speed – on forward wheels and 1 sensor on a back axis were installed. Since 1985 4 sensors – on one on a wheel are installed. 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 of hydraulics therefore pressure in a contour of a wheel falls, causing its unblocking.

In system points out fire of a control lamp of "ABS" on a guard of devices malfunction. 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, then replace the sensor (sensor is executed with conducting at the same time).


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

Diagnostics and repair

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

1. Check the level of brake fluid 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, then address to car service.