Audi Workshop Service and Repair Manuals

Special tools and workshop equipment required

• ◆ Brake pedal depressor V.A.G 1869/2

• ◆ Repair set, Part no.

=> Parts List

•     1 -    Transportation protection for valve domes (foam)
•     2 -    Sealing plug M10 for brake pipes and tapped holes
•     3 -    Sealing plug M12 for brake pipes and tapped holes

After separating control unit from hydraulic unit, always attach transportation protection for valve domes to hydraulic unit.

No warranty claims can be accepted for hydraulic units not fitted with transportation protection for valve domes.

Removing

• ‒ → If fitted, remove front left cover -arrows-.

• ‒ → If fitted, disconnect air intake hose for secondary air pump -1- from air cleaner housing.
• ‒ Detach air hose -2- at air-mass meter.
• ‒ Unplug connector for air-mass meter -3-.
• ‒ Screw out bolts -4- and -5-.
• ‒ Take out air cleaner housing.

• ‒ → Insert brake pedal depressor V.A.G 1869/2 between brake pedal and driver's seat. Depress brake pedal at least 60 mm.
• ‒ Connect hose of bleeder bottle to bleed screw of front left and rear left brake caliper and open bleed screws.

Note:

This dissipates pressure in hydraulic unit.

• ‒ Close front left and rear left bleed screws.
• ‒ Leave brake pedal depressor V.A.G 1869/2 in position.

• ‒ → Release -arrow 1- connector at control unit and unplug -arrow 2-.

Notes:

• ◆ Make sure brake fluid does not ingress into connector housing of control unit as this could result in contact corrosion and thus system failure.
• ◆ Use compressed air to carefully clean dirty connector housing.

• ‒ As protection against escaping brake fluid, place a sufficient number of lint-free cloths in area beneath control unit and hydraulic unit.
• ‒ Mark brake pipes.
• ‒ → Unscrew brake pipes from hydraulic unit to brake master cylinder
  -arrows- and tie in place.
• ‒ Unscrew the remaining brake pipes from the hydraulic unit.

• ‒ Seal brake pipes and tapped holes with sealing plugs from repair set.

• ‒ → Screw out bolts at bracket for hydraulic unit -arrows- and detach hydraulic unit with control unit.

Unscrewing control unit from hydraulic unit

• ‒ Unplug connector for hydraulic pump at control unit.
• ‒ → Screw out TORX bolts -arrows- of control unit and detach control unit.

• ‒ → When detaching control unit, make sure valve domes of hydraulic unit do not catch on control unit solenoids.
• ‒ Cover control unit solenoids with a lint-free cloth.
• ‒ Protect components against moisture.
• ‒ After disconnecting control unit and hydraulic unit, fit transportation protection for valve domes from repair set.

Installing

Install in reverse order, paying attention to the following:

Notes:

• ◆ Do not remove sealing plugs from new hydraulic unit until appropriate brake pipe is to be fitted.
• ◆ If sealing plugs are removed from hydraulic unit sooner, brake fluid may escape and it may no longer be possible to fill and bleed the unit properly.

• ‒ When assembling control unit and hydraulic unit, make sure valve domes of hydraulic unit do not catch on control unit solenoids.

• ‒ → Connect pipes as marked.

•     A -    Secondary piston circuit
•     B -    Primary piston circuit
•     1 -    To front right brake caliper
•     2 -    To rear left brake caliper
•     3 -    To rear right brake caliper
•     4 -    To front left brake caliper

• ‒ Attach connector to hydraulic pump.

• ‒ Screw ABS unit to bracket.

Note:

Do not fully tighten bolts to facilitate attachment of individual brake pipes to hydraulic unit.

• ‒ Finish tightening hydraulic unit after screwing on brake pipes.
• ‒ Bleed brake system .
• ‒ If a new control unit is fitted, it must be encoded.

=> Running Gear, Self-diagnosis; Repair Group 01

• ‒ Perform final control diagnosis after attaching brake pipes to hydraulic unit.

=> Running Gear, Self-diagnosis; Repair Group 01

Note:

Final control diagnosis can be used to establish whether pipe connections have been interchanged.

Tightening torques

    1)    Replace bolts

    2)    For M10 and M12 connections