Control Module and Hydraulic Unit, Removing and Installing

Notes: Note safety precautions.

Special tools and workshop equipment required





^ V.A.G 1 331 Torque wrench

To bolt the control module to the hydraulic unit, use torque wrench V.A.G 1410.





^ V.A.G 1869/2 Brake pedal depressor

Additional information
Refer to On Board Diagnostics.

Location
The control module is bolted to the hydraulic unit and is located on the left in the engine compartment.

WARNING: Do not bend the brake lines in the area of the hydraulic unit!

Removing
^ Note or request radio code on vehicles with coded radio if necessary.
^ Disconnect battery.





^ Pull air mass sensor connector - 1 - off air intake duct.
^ Remove bolts - 2 - on air cleaner housing - 3 - and place air cleaner housing to side on left.
^ Draw off as much brake fluid as possible from brake fluid reservoir using a suction bottle.
^ Connect bleeder bottle to bleeder screw on front left brake caliper and open the bleeder screw.
^ Insert brake pedal depressor between brake pedal and driver's seat. Depress the brake pedal by at least 60 mm.

Notes:
^ This prevents the brake fluid reservoir from running dry.
^ The brake pedal depressor must remain in position until all the brake lines have been connected to the hydraulic unit.

^ Close front left bleeder screw.





^ Release control module connector and unplug.

Notes: Cover the engine compartment to ensure that no brake fluid flows into it.





^ Disconnect brake lines from hydraulic unit to brake master cylinder - arrows - and tie up.
^ Disconnect remaining brake lines on hydraulic unit.
^ Seal brake lines and threaded holes with plugs from repair set 1 HO 698 311 A.





^ Remove bolts on hydraulic unit bracket - arrows -
^ Remove hydraulic unit with control module. Removing control module from hydraulic unit
^ Pull connector for hydraulic pump motor off control module.





^ Remove Torx head bolts E5 - arrows - from control module and pull off control module.





^ When removing control module, ensure that hydraulic unit valve dome is not canted against control module solenoid valves.
^ Cover control module magnetic coils with a lint - free cloth.
^ After separating control module and hydraulic unit use transportation protection for valve dome.

Notes:
^ Only remove sealing plugs on new hydraulic unit when the corresponding brake line is going to be fitted.
^ 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.

Tightening torques:
Control nodule to hydraulic unit maximum Tighten to 4 Nm
Hydraulic unit hexagon bolt to bracket Tighten to 8 Nm
Nut for tandem nester brake cylinder to brake servo Tighten to 25 Nm
Brake lines to ABS unit:
Thread M 10 x 1 15 Nm
Thread M 12 x 1 15 Nm

^ When assembling control module and hydraulic unit, ensure that the hydraulic unit valve dome is not canted against the control module solenoid valves.
^ Using new bolts, screw control module to hydraulic unit.

Tightening torque: maximum 4 Nm.

^ Fit wiring connector on hydraulic pump motor.
^ Bolt ABS unit to bracket.
^ Do not tighten bolts completely. Attaching the individual brake lines is made easier.
^ After tightening brake lines, tighten hydraulic unit.

Further installation is the reverse order of removal.
^ Bleed brake system .
^ Code control module, Refer to On Board Diagnostics.

Work to be carried out after completing repairs .
^ Check the notes on road testing .