Opel Corsa B 1993–2000 Service and Repair Manual: Anti-lock braking system (ABS) components - removal and refitting

Wheel speed sensor

Note: The rear wheel speed sensor on 1992 model year vehicles has its pulse pick-up point unit integral in the hub housing. In the event of the pick-up unit malfunctioning, it will need to be renewed complete with the rear wheel hub unit.

1. Disconnect the battery earth (negative) lead.

2. Remove the single securing screw and withdraw the sensor (see illustrations).

ABS rear wheel speed sensor on brake backplate securing screw arrowed

ABS front wheel speed sensor

Removing a front wheel speed sensor

ABS rear wheel speed sensor (arrowed) on models with rear drum brakes

3. Follow the wiring back from the sensor to the connector. Unclip the connector and separate the two halves (see illustrations).

Rear sensor connectors next to petrol tank (earlier models)

Separating a front sensor connector

4. Refitting is the reverse of the removal procedure, but apply a smear of grease or anti-seize compound to the body of the sensor. Check for correct operation of the ABS on completion.

Electronic control unit (ECU)

5. Disconnect the battery earth (negative) lead.

6. Remove the under-dash trim on the passenger (left-hand) side. This is secured by four clips.

7. Remove the ECU from its bracket. Release the spring clip, disconnect the multi-plug and remove the ECU.

8. Refitting is the reverse of the removal procedure. Check for correct operation of the ABS on completion.

ABS surge arrester relay

9. Disconnect the battery earth (negative) lead.

10. Unscrew or unclip the relay bracket. It is on the left-hand suspension turret; the relay is the one nearest the ABS hydraulic unit (see illustration). Disconnect the multi-plug from the relay and remove it.

ABS surge arrester relay (arrowed)

11. Note that the relay carries its own fuse.

This fuse should be checked before condemning the relay.

12. Refitting is the reverse of the removal procedure.

ABS hydraulic unit removal and refitting

13. Disconnect the battery earth (negative) lead.

14. To minimise hydraulic fluid loss, top-up the reservoir to the maximum level and seal the cap by tightening it down over a piece of cling film, or by blocking the vent hole temporarily with a piece of tape.

15. Remove the hydraulic unit cover, which is secured by two screws (see illustration).

Two screws (arrowed) which secure the hydraulic unit cover

16. Remove the two relays from the unit.

Release the multi-plug catch by squeezing its two halves together and disconnect the multi-plug (see illustrations).

Removing the relays from the hydraulic unit

Squeeze the multi-plug catch (arrowed) to realise it

17. Clean around the hydraulic unions on the unit. Make identifying marks if necessary so that each pipe can be refitted to its original location, then disconnect the hydraulic pipes from the unit. Cap or plug open pipes and unions.

18. Undo the three mounting bolts. (Where slotted mounting holes are used there is no need to remove the bolts completely.) Disconnect the earth strap from the hydraulic unit pump and remove the unit.

19. A defective hydraulic unit must be exchanged or renewed. Retain the relays from the old unit and fit them to the new one. The relay nearest the hydraulic connectors controls the solenoid valves and the other one controls the pump motor.

20. Refitting is the reverse of the removal procedure, noting the following points:

1. Tighten the mounting bolts to the specified torque
2. Bleed the hydraulic system on completion