Anti-lock Brake System (ABS) Components — Removal and Installation (BMW 3 Series E46)

Hydraulic block

1. Removal and installation of the hydraulic unit in a garage is impossible, since this requires special diagnostic equipment, and BMW equipment is required to bleed the system. In this regard, we recommend that you transfer this work to a specialized service station.

Battery (models with ASC+T system)

2. For the reasons stated in point 1 of this paragraph, we recommend that you entrust this work to service station specialists.

Electronic control unit (ECU)

3. To remove this unit, you must first remove the hydraulic unit, since the ECU is attached to the wall of the hydraulic unit. In this regard, we recommend that you entrust this work to service station specialists.

Front wheel sensors

Removal

4. Place chocks under the rear wheels and apply the parking brake. Raise the front of the vehicle and support it on jack stands (see "Raising and Supporting the Vehicle"). Remove the appropriate front wheel. Locate the sensor wiring connector (the connector is located in a plastic protective casing). Remove the cover, take out the connector, and disconnect it (Fig. 20.4).



5. Unscrew the bolt securing the sensor to the steering knuckle and remove the sensor together with the electrical wiring from the vehicle (Fig. 20.5). Note: On some models, the left and right wheel sensors are marked L and R, respectively. In addition, the right sensor has two green marks between the sensor and the gasket.

Installation

6. Apply a small amount of universal grease to the sensor before installation (bMW recommends Staborax NBU 12/k grease).

7. Make sure the mating surfaces of the steering knuckle and sensor are clean, then install the sensor. Make sure the sensor is installed on the correct side of the vehicle (where necessary, see paragraph 5). Screw in the mounting bolt and tighten it to the required torque.

8. Make sure the sensor wiring is routed correctly and secured. Connect the wiring connector. Place the connector in the housing and secure the cover.

9. Install the wheel, lower the vehicle to the ground and tighten the wheel mounting bolts to the specified torque.

Rear wheel sensors

Removal

10. Place chocks under the front wheels. Raise the rear of the vehicle and support it (see "Raising and Supporting the Vehicle"). Remove the appropriate rear wheel.

11. Remove the sensor (see points 4 and 5).

Installation

12. Install the sensor as described in paragraphs 6-9.

Front wheel sensor rotors

13. The rotors are mounted on the back of the hubs. Inspect the rotors for damage and chipped teeth. If a rotor needs to be replaced, disassemble the hub assembly and replace the bearings (see chapter 10).

Rear wheel sensor rotors

14. The rotors are mounted on external constant velocity joints. Inspect the rotors for damage and chipped teeth. If a rotor needs to be replaced, replace the drive shaft assembly (see chapter 8).