Hydraulic Control Unit, Removing and Installing

Hydraulic control unit, removing and installing

Special tools and workshop equipment required

Location

The hydraulic control unit is installed on the left hand side of the engine compartment.

Removing

CAUTION: Brake lines must not be bent.

See Caution before beginning repairs on the electrical system
- Disconnect battery.

- Unlatch the connector from the control unit in the direction of the arrow and pull it off.
- Insert brake pedal depressor between brake pedal and driver's seat. Depress the brake pedal by at least 60 mm.
The brake pedal depressor must remain in position until all the brake lines have been reconnected to the hydraulic unit.

Note:
^ Protect the engine compartment against escaping brake fluid.

- Unscrew brake line connections on hydraulic unit.

- Undo bolt -1- and pull it out in the direction of the arrow and swivel the coolant expansion tank to one side.
- Tightening torque: 6 Nm.

- Seal brake lines and threaded holes with plugs from repair set Part No. 1H0698311 A.

Note:
^ Protect the plenum chamber and the engine compartment against any escaping brake fluid.

- Unscrew and remove lines -1-, -2- and -3-.

- Detach brake lines -1- and -2- and seal with dummy plugs from the repair kit Part No. 1 HO 698 311 A

- Detach plug connections (see arrows).
- -Unclip brake lines from holder.

- Release the locking clip from below -1- and pull it out in the direction of the arrow.
- Remove hydraulic control unit.

Installing
Pay special attention to the following on installation:
^ Only remove sealing plugs on new hydraulic control unit when the corresponding brake line is about to be installed.
^ If the sealing plugs are removed too early, brake fluid can escape, it can then no longer be guaranteed that the unit is sufficiently filled or adequately bled.

- Bleeding brake system, Refer to Brake Bleeding, Service and Repair
- Enter radio code.
See Caution for connecting Telematics battery
- Connect battery ground strap.