Anti-lock braking system ABS, components — removal and installation (Opel Astra F)

Hydraulic modulator

Removal

Disconnect the negative battery terminal.

Remove the brake fluid reservoir cap and tape a piece of plastic over the filler neck or reinstall the cap. This will reduce fluid loss during operations.

Remove the screw and plastic cover from the hydraulic modulator (Fig. 9.31).



Disconnect the plug contact of the control unit and the solenoid valve. Note that the control unit contact is secured with a screw (fig. 9.32, 9.33.).





Loosen the nuts and disconnect the brake fluid tubes from the modulator. Fluid may leak, so close the hole. Move the tubes away from the modulator.



Unscrew the three nuts, then tilt the modulator slightly and remove it, separating it from the bracket, but in such a way that there is access to the ground wire nut to the mass (fig. 9.34, 9.35.).





Loosen the nut and disconnect the ground wire, then remove the modulator from the vehicle, being careful not to spill brake fluid on the painted surfaces of the vehicle.

If you need to install a new modulator, remove the two relays on top of the old modulator and reinstall them on the new one. Do not attempt to disassemble the modulator.

Installation

Before installing the modulator, check that the mounting bolts of the support bracket to the body panel are tightly tightened. The rubber support must be in good condition. Replace it if necessary.



Installation is carried out in the reverse order of removal, taking into account the following.

Make sure the ground wire is connected before you begin installing the modulator onto the support bracket.

Remove the plastic film from the neck of the brake fluid reservoir and bleed the hydraulic system as described in the second section of this chapter.

Make sure that the ABS warning light goes out after the first start of the engine with the starter, if the modulator has already been removed from the engine. At the first opportunity, take the car to a car repair shop to check the entire system using special equipment.

Front wheel sensor

Disconnect the negative battery terminal.

Apply the handbrake, then jack up the front of the car and secure it on the stands under the axle.

Disconnect the sensor contact from the spring clip located under the wheel arch, then disconnect the connector.

Use a socket wrench to loosen the wheel sensor bolt on the mounting bracket, then carefully remove it with a screwdriver. Remove the O-ring (fig. 9.36.).



Check the condition of the sealing ring and replace it if necessary.



Installation is carried out in the reverse order of removal, taking into account the following.

Apply a small amount of grease to the sensor body before installing it on the bracket.

Make sure that the ABS warning light goes out when the engine is started for the first time. Have the ABS system checked at a workshop using special equipment as soon as possible.

Rear wheel sensor

The rear wheel sensors are integral with the rear wheel hub assembly and cannot be separated from the hub. More details about this see chapter 10 (Fig. 9.37).

Electronic control unit

Make sure the ignition is off, then disconnect the negative battery terminal.

The block is connected to the hydraulic modulator assembly located in the engine compartment.



Remove the screw and plastic cover from the hydraulic modulator.

Disconnect the control unit plug and solenoid valve wires.

Remove the two relays from the top of the assembly.

Disconnect the remaining connector from the control unit.

Remove the seven screws and remove the control unit from the modulator assembly.

Installation is carried out in the reverse order of removal, but try not to overtighten the control unit screws.

Relay

Two relays are used: one for the solenoid valve and one for the pump motor; both of them are installed on the control unit (Fig. 9.38).



Disconnect the negative battery terminal.

Remove the screw and plastic cover from the hydraulic modulator.

Remove the corresponding relay.

Installation is carried out in the reverse order of removal.

Make sure that the ABS warning light goes out after the first engine start. Have the entire system checked at a workshop using special equipment as soon as possible.