Volkswagen Golf / Golf GTI / Jetta. Manual — part 402

45-4

Thoroughly clean all connections and the

adjacent areas before loosening. Do not use
aggressive cleaning agents such as brake
cleaner, gasoline, thinners or similar.

Place removed parts on a clean surface and

cover them. Only use clean plastic covering or
paper. Do not use rags that may contain lint.

After separating the control module from the

hydraulic unit, use the transportation protection
for the valve dome.

Carefully cover or seal open components if

repairs cannot be carried out immediately. Use
the sealing plugs contained in repair kit, Part
No. 1 H0 693 311 A.

Do not use rags that may contain lint.

Only remove replacement parts from packaging

immediately prior to installation.

Only use genuine packed parts.

When the system is open do not work with

compressed air and do not move the vehicle.

Make sure that no brake fluid enters electrical

connectors.

Anti-lock brake system (ABS) and anti-lock brake system with electronic differenti...

45-5

Hydraulic unit,
brake
booster/master
cylinder,
overview

Note:

Complete brake master
cylinders and brake
boosters can be
replaced separately.

1 - Brake Booster

For gasoline

engines
vacuum is
taken from the
intake manifold

Diesel engines

have a vacuum
pump to create
the required
vacuum

Functional

check:

- With engine

switched off,
depress
brake pedal
firmly several
times (to
exhaust
vacuum in
the unit)

-

Hold brake
pedal with
average foot
pressure in
brake
position and
start engine.
If brake
booster is
functioning

Hydraulic unit, brake booster/master cylinder, overview

properly,
brake pedal
should give
noticeably
underfoot.

If pedal does

not give,
replace brake
booster

Hydraulic unit, brake booster/master cylinder, overview

45-6

Check

valve (in
vacuum
hose

Page 47-
49

Functional

check

Page 47-
49

Separating

from brake
pedal

Page 46-
79

.

Removing

and
installing

Page

47-84

2 - Cap

3 - Brake

fluid
reservoir

4 - Plug

Coat

with
brake
fluid and
press
into
reservoir

5 - Retaining

pin

Insert

through
brake
master
cylinder

6 - Brake

master
cylinder

Cannot

Hydraulic unit, brake booster/master cylinder, overview