Anti-lock braking system (ABS) — removal and installation (Opel Frontera A)

ABS consists of an electronic control unit, sensors located on the wheels, a hydraulic unit, valves and relays.

The ABS unit is located between the master cylinder and the brakes. The presence of ABS does not affect the design of the vacuum booster and the master brake cylinder.



The front wheel sensors are located in the steering knuckles as shown. They control the number of revolutions of the vehicle's wheels through gear rings mounted on the front drives.



The rear wheel sensors are mounted to the rear axle beam as shown.



If any problems with the ABS system occur, you should contact an Opel auto repair shop that has special diagnostic equipment. If the ABS indicator lights up, you can continue driving, but the system does not work.

Replacing the front wheel speed sensors

The front wheel sensors are removed and installed as follows:

Removal

1. Disconnect the ground cable from the battery.

2. Raise and support the front of the vehicle on stands.

3. Remove the wheel, allowing access to the sensor cable.

4. Remove the plug connection in the wheel housing from the holder and unplug it using a screwdriver.

5. If there are multiple plug connections, determine which one is for the ABS sensor.

6. Disconnect the cable from the mount.

7. Use a socket wrench to unscrew the sensor mounting bolt and carefully separate it with a screwdriver.

Installation

The sensor is installed in the reverse order of removal.

1. Tighten the mounting bolt to a torque of 9 Nm.

2. Be careful not to twist the sensor cable. The cable is marked with a white line.

3. When tightening the cable mounting bolts, pay attention to the different tightening torques.

4. The lower cable mounting bolt is secured with a torque of 27 Nm, the upper cable with a torque of 6 Nm.

5. Make sure that the speed sensor is not dirty or damaged.

6. After completing the work, return the ignition key to the working position and check that the ABS indicator goes out.

Replacing the rear wheel speed sensors

Removal

1. Disconnect the ground cable from the battery, raise and support the rear of the vehicle on stands.



2. Locate the sensor cable and unplug the connector, disconnect the cable from the mount.



3. Unscrew the sensor. The location of the sensor on the rear suspension is shown in the illustration.

Installation

The sensor is installed in the reverse order of removal.

1. Be careful not to twist the cable when connecting. For correct installation, the cable is marked with a white line.

2. Tighten the sensor mounting bolts to a torque of 22 Nm, and the cable mounting bolts to a torque of 27 Nm.

Wheel Speed Sensor Guidelines

The wheel speed sensor consists of a magnetic core and a coil. The operating principle of the sensor is explained in the diagram in the illustration.





The pole piece projection is surrounded by a magnetic field. During rotation, the teeth of the toothed rotor intersect the magnetic field. This leads to a distortion of the field, which in turn indicates an alternating voltage in the sensor coil. The frequency of voltage change corresponds to the number of wheel revolutions. The corresponding information is sent to the control unit.

Toothed rotors (otherwise they are called impulse rings) have 54 teeth. At the front, the rotors are secured with three bolts to the inside of the hub/brake disc assembly. At the rear, the toothed rotors are pressed onto the drives.

Replacing the front wheel sensor rotor

1. Remove the front hub as described in the appropriate section.



2. Remove the rotor from the inside of the wheel hub.

3. If the removed rotor is installed back, the tooth surfaces must be checked. They must not have any damage.

Text copied from a web portal [OpelBook.ru]

4. When installing, tighten the bolts to a torque of 18 Nm.

Replacing the rear wheel sensor rotor

1. Raise and support the rear of the vehicle on stands.

2. Remove the rear drive as described in the relevant section.



3. Remove and install the toothed rotor in connection with the replacement of the drive bearing.

4. The work mentioned is also described in Chapter Brake system