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Home >> Audi >> 2009 >> S4 Automatic >> Repair and Diagnosis >> Brakes >> Traction Control >> Brake System >> 45 - Anti-lock brake system >> Anti-lock brake system (ABS) Bosch 5.7 >> Hydraulic control unit, removing and installing

Hydraulic control unit, removing and installing

Special tools, testers and auxiliary items required 

Fig 1: Identifying Brake Pedal Depressor V.A.G 1869/2
GW00004500Courtesy of VOLKSWAGEN UNITED STATES, INC.
Fig 2: Sealing Plug Repair Set, Part No. 1H0 698 311 A
GW00011054Courtesy of VOLKSWAGEN UNITED STATES, INC.

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

Location:

Fig 3: ABS Layout
GW00006751Courtesy 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.
Fig 4: Removing Connector From Control Module
GW00006782Courtesy of VOLKSWAGEN UNITED STATES, INC.

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.
Fig 5: Locating Securing Bolt And Pulling Coolant Expansion Tank
GW00019676Courtesy of VOLKSWAGEN UNITED STATES, INC.
Fig 6: Identifying Brake Lines
GW00019677Courtesy of VOLKSWAGEN UNITED STATES, INC.
NOTE:
  • Protect plenum chamber and engine compartment against escaping brake fluid.
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
GW00019678Courtesy of VOLKSWAGEN UNITED STATES, INC.
Fig 8: Locating Connectors & Unclipping Brake Lines From Bracket
GW00019679Courtesy of VOLKSWAGEN UNITED STATES, INC.
Fig 9: Identifying Locking Clips
GW00006783Courtesy of VOLKSWAGEN UNITED STATES, INC.

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.

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