Removing and installing control until and hydraulic unit — AUDI

Special tools and workshop equipment required

Brake pedal depressor V.A.G 1869/2

Repair kit; Part No.

=> Parts catalogue

1 -
Valve dome transportation protection (plastic foam)
2 -
M10 sealing plugs for brake pipes and threaded holes
3 -
M12 sealing plugs for brake pipes and threaded holes

After separating the control unit from the hydraulic unit always fit the valve dome transportation protection on the hydraulic unit.

Warranty claims for hydraulic units on which the valve dome transportation protection was not used, will not be accepted.

Removing

Remove forward left-hand cover panel -arrows-.

If installed, disconnect secondary air intake hose -1- from air cleaner.
Disconnect air hose -2- from air mass meter.
Unplug connector -3- from air mass meter.
Unscrew bolts -4- and -5-.
Remove air cleaner housing.

Insert brake pedal depressor V.A.G 1869/2 between brake pedal and driver's seat. Depress the brake pedal by at least 60 mm.
Connect hose of bleeder bottle to bleeder screws on front left and rear left brake calipers and open bleeder screws.

Note:

This dissipates pressure in hydraulic unit.

Close front left and rear left bleeder screws.
Do not remove brake pedal depressor V.A.G 18169/2.

Release control unit connector -arrow 1- and unplug -arrow 2-.

Notes:

Protect connector housing of control unit against escaping brake fluid. Otherwise corroding contacts can cause a breakdown of the system.
Carefully clean a moist or dirty connector housing with compressed air.

Lay out sufficient lint-free cloths in area below control unit and hydraulic unit.
Mark brake pipes.
Disconnect brake pipes -1- from hydraulic unit to brake master cylinder and tie up.
Disconnect remaining brake pipes on hydraulic unit.

Warning:
Take care not to bend brake pipes in the vicinity of the hydraulic unit.
Seal brake pipes and threaded holes with plugs from repair set.
Unscrew bolts at hydraulic unit -arrows- and take out hydraulic unit and control unit.

Removing control unit from hydraulic unit

Place hydraulic unit with control unit down on a clean flat surface.
Remove Torx socket head bolts -arrows-.

Warning:
The hydraulic pump must not be separated from the hydraulic unit.
Separate hydraulic unit with hydraulic pump from control unit by lifting carefully off joint -1-.

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.
Fit transportation protection for valve domes (enclosed in repair kit) after separating control unit and hydraulic unit.

Note:

The valve dome -2- supplied as spare part with the control unit can only be clipped in once. It is not possible to separate the connection afterwards.

Installing

Install in reverse sequence; note the following points:

Notes:

Only remove sealing plugs on new hydraulic unit when the corresponding brake pipe is going to be fitted.
If the sealing plugs are removed too soon from the hydraulic unit, brake fluid may escape, 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 previously marked => Page
45-85
.
Bolt ABS unit to bracket.

Note:

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

After tightening brake pipes, tighten hydraulic unit.

Bleed brake system => Page
47-40
.
If a new control unit has been fitted it must be coded.

=> Running gear, Self-diagnosis; Repair group 01
Running gear, Self-diagnosis

After connecting brake pipes to hydraulic unit, perform final control diagnosis.

=> Running gear, Self-diagnosis; Repair group 01
Running gear, Self-diagnosis

Note:

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

Tightening torques

Component · Nm
Control unit to hydraulic unit · 4 1)
Hydraulic unit to bracket · 8
Brake pipes to hydraulic unit · 14 2)
Air cleaner housing · 10

1)
Renew bolts

2)
for M10-connections and M12-connections