Hydraulic Unit Control Unit Replacement

ABS hydraulic control unit, removing and installing

Note: When working with brake fluid, observe the relevant safety precautions and notes refer to Brake system, bleeding. Refer to Brake hydraulic system, bleeding and changing brake fluid.

Special tools and equipment
- Sealing plugs from repair kit Part No. 1H0 698 311A
- Brake pedal depressor, e.g. from VAG1813

CAUTION: Part numbers are listed here for reference only. Always check with your Parts department for the latest information.

Component location:

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

Removing

CAUTION:
- Do not bend the brake lines.
- Before disconnecting the battery, determine the correct coding for the anti-theft radio.

- Disconnect battery Ground (GND) strap.

- Release control unit connector (arrow -1-) and disconnect harness connector (arrow -2-).
- Connect bleeder bottle to bleeder screw on left-front brake caliper and open bleeder screw.
- Install brake pedal depressor between brake pedal and driver's seat. Depress brake pedal by at least 60 mm (2 3/8 inch).

Note: The brake pedal depressor must remain in position until all of the brake lines have been reconnected to the hydraulic control unit.

- Close left-front bleeder screw.
- Cover engine compartment to make sure brake fluid does not flow into it.
- Disconnect brake line connections on hydraulic control unit.
- Seal brake lines and threaded holes using plugs from repair kit, Part No. 1HO 698 311 A.
- Remove nuts from ABS hydraulic control unit bracket.
- Remove ABS hydraulic control unit.

Installing

Note: When installing, pay particular attention to the following points.
- Only remove the sealing plugs on the new hydraulic control unit when the corresponding brake line is about to be installed.
- If the sealing plugs are removed too early the brake fluid can escape. If this occurs, the unit will no longer be sufficiently filled or adequately bled.

- Bleed brake system.
- Enter radio code.