Note: After performing any of the procedures described in this chapter, it is recommended that the anti-lock braking system be fully checked by an Audi dealer.
Hydraulic modulator
1. Disconnect the negative battery cable.
2. Where equipped, remove the coolant expansion tank as described in Section 2, and move it to the side.
3. Mark exactly the location of each brake line! on the hydraulic modulator.
4. Turn off a cover of an additional reservoir of brake system. Cover it with a piece of polyethylene to reduce fluid loss. Alternatively, liquid may be pumped out of the reservoir and may into a container.
5. Loosen the union nuts, disconnect the brake lines Plug the ends of the pipes, or cover them with adhesive tape to prevent dust and dirt from entering.
6. Lift cover off modulator, disconnect harness retainer and wiring.
7. Unscrew the mounting nuts, remove the modulator from the suspension.
8. Installation is carried out in the reverse order. Bleed the entire hydraulic system as described in Chapter 17.
Electronic control device
9. It is located under the left rear seat cushion.
10. Check that the ignition is off.
11. Remove seat cushion (Section 11).
12. Press the fixing spring, disconnect the multi-pin electrical wiring plug.
13. Unscrew both fastening screws, remove the electronic control device.
14. Installation is carried out in the reverse order, but make sure that the retaining spring is fully inserted to secure the multi-pin plug.
Relay
15. There are two relays on the hydraulic modulator, one for the solenoid valve and one for the return pump. There is also a combination relay located in an additional relay box under the dashboard.
16. Turn off the ignition before removing the relay.
17. First remove the cover, then remove the relay from its socket.
18. To remove the relay from the optional relay box, refer to Section 12.
19. Installation is carried out in the reverse order.
Wheel speed sensors
20. Jack up the front or rear of the car and support it on axle stands. Remove the wheel.
21. On early models, the sensor is bolted on. If the sensor is to be reused, mark the exact position of the bolt in the elongated hole with a smear of paint. Unscrew the bolt, remove the sensor from the bushing in the wheel bearing housing or rear axle. Remove seal.
22. On later models, the sensor is attached with a clamp sleeve. Pull the sensor out, then remove the clamp bushing from the wheel bearing housing or rear axle.
23. Release the sensor wiring from the suspension by pulling out the rubber o-ring.
24. Separate the located electrical wiring connector in the engine compartment or under the rear seat cushion. On models with fuel injection, first disconnect the air duct from the air flow meter and move it to the side.
25. Before installing the rear sensor, check and, if necessary, adjust the clearance of the rear wheel bearing, as described in Section 10.
26. To install the sensor on early models, it is recommended to install a new PVC tip on the sensor. If the sensor will be installed exactly in the marked position, this is not required. Install new seal, coat seal and sensor with paste. Insert the sensor, tighten the bolt while pushing the sensor until the PVC tip touches the rotor.
27. When installing the sensor on late models, first coat the clamp bushing with paste and insert it fully into the wheel bearing housing or rear axle. Push the transducer fully into the clamp sleeve. Install the rubber boot on the rear sensor (if available).
28. Connect electrical wiring and, where equipped, air duct.
29. Insert the rubber o-ring into the hanger to secure the electrical wiring.
30. Install the wheel and lower the vehicle to the ground.
Wheel speed sensor rotors
31. The front sensor rotors are included in the outer pivots of the drive shaft. Connections can be replaced separately as described in Section 8.
32. Before removing the rear sensor rotor, first remove the hub as described in Section 10.
33. Clamp the hub in a vice, knock out the rotor with a punch through the holes for the wheel bolt.
34. A metal tube must be used to mount the rotor on the hub, being careful not to damage the special sensor.
35. Install the hub as described in Section 10.
Visitor comments