Hydraulic control unit, removing and installing

WARNING: This page does not describe the selected car, but rather 17 other vehicles, including the 2009 Audi S4, 2009 Audi A4, 2008 Audi S4, 2008 Audi RS 4, and 2008 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Special tools, testers and auxiliary items required

Fig 1: Identifying Brake Pedal Depressor V.A.G 1869/2

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Brake pedal depressor V.A.G 1869/2

Fig 2: Sealing Plug Repair Set, Part No. 1H0 698 311 A

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Sealing plug repair kit, Part no. 1H0 698 311 A

Location:

Fig 3: ABS Layout

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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

Removing

CAUTION: Brake lines must not be bent.

Note or request radio code on vehicles with coded radio, if necessary.
Disconnect battery. →
- 27 BATTERY, STARTER, GENERATOR, CRUISE CONTROL
- 27 - BATTERY, STARTER, GENERATOR, CRUISE CONTROL for ELECTRICAL EQUIPMENT - GENERAL INFORMATION

Fig 4: Removing Connector From Control Module

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Release connector from control unit in direction of - arrow - and disconnect.
Insert brake pedal actuator V.A.G 1869/2 between brake pedal and drivers seat. Depress brake pedal at least 60 mm.

The brake pedal actuator V.A.G 1869/2 must remain in position until all brake lines have been reconnected to the hydraulic unit.

NOTE:

Protect engine compartment against escaping brake fluid.

Disconnect brake lines from hydraulic unit.

Fig 5: Locating Securing Bolt And Pulling Coolant Expansion Tank

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Loosen securing bolt - 1 - and pull coolant expansion tank out in direction of - arrow - , then swivel tank to one side.
Tightening torque: 6 Nm

Fig 6: Identifying Brake Lines

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Seal brake lines and threaded holes with plugs from repair kit Part No. 1H0 698 311 A.

NOTE:

Protect plenum chamber and engine compartment against escaping brake fluid.

Remove lines - 1 - , -2- and - 3 -.

NOTE:

On vehicles from model year 2002 a flexible hose has been installed as part of the brake lines; on vehicles built before model year 2002 the brake lines have to be disconnected at brake booster.

Fig 7: Disconnecting Brake Lines And Sealing With Sealing Plugs From Repair Kit, Part No. 1H0 698 311 A

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Disconnect brake lines - 1 - and - 2 - and seal with sealing plugs from repair kit, Part No. 1H0 698 311 A.

Fig 8: Locating Connectors & Unclipping Brake Lines From Bracket

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Loosen connectors -1-.
Unclip brake lines from bracket - 2 -.

Fig 9: Identifying Locking Clips

Courtesy of VOLKSWAGEN UNITED STATES, INC.

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

Installing

When installing, observe the following:

NOTE:

Do not remove sealing plugs from new hydraulic control unit until corresponding brake line is to be installed.
If sealing plugs are removed too early, brake fluid can escape, and can no longer be guaranteed that unit is sufficiently filled or adequately bled.

Bleed brake system.
Enter radio code.
Connect battery. →
- 27 BATTERY, STARTER, GENERATOR, CRUISE CONTROL
- 27 - BATTERY, STARTER, GENERATOR, CRUISE CONTROL for ELECTRICAL EQUIPMENT - GENERAL INFORMATION

Tightening torques

Component	Nm
Brake lines to hydraulic unit M10 (brake line diameter 5 mm)	12
Brake lines to hydraulic unit M12 (brake line diameter 5 mm)	12
Brake lines to hydraulic unit M12 (brake line diameter 8 mm)	20