Subaru Legacy IV (2008 year). Manual - part 917

VDC-6

General Description

VEHICLE DYNAMICS CONTROL (VDC)

C: CAUTION

• Wear appropriate work clothing, including a cap, protective goggles and protective shoes when performing
any work.
• Remove contamination including dirt and corrosion before removal, installation or disassembly.
• Keep the disassembled parts in order and protect them from dust and dirt.
• Before disconnecting connectors of sensors or units, be sure to disconnect the ground cable from the bat-
tery.
• Before removal, installation or disassembly, be sure to clarify the failure. Avoid unnecessary removal, in-
stallation, disassembly and replacement.
• Vehicle components are extremely hot after driving. Be wary of receiving burns from heated parts.
• Be sure to tighten fasteners including bolts and nuts to the specified torque.
• Place shop jacks or rigid racks at the specified points.

D: PREPARATION TOOL

1. SPECIAL TOOL

2. GENERAL TOOL

ILLUSTRATION

TOOL NUMBER

DESCRIPTION

REMARKS

1B022XU0

SUBARU SELECT 
MONITOR III KIT

Used for troubleshooting the electrical system.

TOOL NAME

REMARKS

Circuit tester

Used for measuring resistance, voltage and current.

Pressure gauge

Used for measuring oil pressure.

Oscilloscope

Used for measuring the sensor.

TORX

®

 bit E5

Used for replacing VDC control module.

ST1B022XU0

VDC-7

VDC Control Module and Hydraulic Control Unit (VDCCM&H/U)

VEHICLE DYNAMICS CONTROL (VDC)

2. VDC Control Module and 

Hydraulic Control Unit 
(VDCCM&H/U)

A: REMOVAL

1) Disconnect the ground cable from the battery.
2) Use compressed air to remove moisture and
dust around the VDCCM&H/U.

NOTE:
If the terminals become dirty, it may cause improp-
er contact.
3) Lift the lock lever and Disconnect the VDC-
CM&H/U connector.

CAUTION:
Do not pull on the harness when disconnecting
the connector.

4) Disconnect the brake pipes from the VDC-
CM&H/U.
5) Wrap the brake pipe with a vinyl bag so as not to
spill the brake fluid on the vehicle body.

CAUTION:
If brake fluid is spilled on the vehicle body, wash
it off immediately with water and wipe clean.
6) Remove the nuts and remove the VDCCM&H/U.

CAUTION:
• Do not drop or bump the VDCCM&H/U.
• Do not turn the VDCCM&H/U upside down or
place it sideways during storage.
• Be careful not to let foreign matter enter the
VDCCM&H/U.
• Be careful that no water enters the connectors.
7) Remove the VDCCM&H/U bracket.

B: INSTALLATION

1) Install the VDCCM&H/U bracket.

Tightening torque:

33 N·m (3.4 kgf-m, 24 ft-lb)

2) Install the VDCCM&H/U with a new nut (Part No.
023506000) by aligning the damper groove of the
VDCCM&H/U to the bracket side claw.

Tightening torque:

7.5 N·m (0.76 kgf-m, 5.5 ft-lb)

3) Connect the brake pipes to their correct VDC-
CM&H/U positions.

Tightening torque:

T1: 15 N·m (1.5 kgf-m, 11.1 ft-lb)
T2: 19 N·m (1.9 kgf-m, 14.0 ft-lb)

4) Connect the VDCCM&H/U connector.

NOTE:
• Be sure to remove all foreign matter from inside
the connector before connecting.
• Make sure the VDCCM&H/U connector is se-
curely locked.
5) Bleed air from the brake system.
6) Check the parameter to confirm that the applied
models and grades of the relevant vehicle are in-
cluded. <Ref. to VDC(diag)-17, PARAMETER
CHECK, OPERATION, Subaru Select Monitor.>

VDC00449

VDC00450

VDC00450

VDC00451

T1

T2

VDC-8

VDC Control Module and Hydraulic Control Unit (VDCCM&H/U)

VEHICLE DYNAMICS CONTROL (VDC)

7) If the applied model and grade of the target ve-
hicle are not included on the {Parameter Check}
display screen, perform parameter selection and
registration. <Ref. to VDC(diag)-16, PARAMETER
SELECTION, OPERATION, Subaru Select Moni-
tor.>

NOTE:
• When the VDCCM&H/U is replaced with a new
part, be sure to perform the selection and registra-
tion operation.
• For the selection and registration of parameter,
the Subaru Select Monitor is required.
• When no data is registered, ABS/EBD/VDC
warning light illuminates and the DTC “Parameter
selection failure” is detected.

C: INSPECTION

1) Check the condition of connection and settle-
ment of connector.
2) Check the mark used for VDCCM&H/U identifi-
cation.
Refer to “SPECIFICATION” for the identification
mark. <Ref. to VDC-2, SPECIFICATION, General
Description.>

1. CHECKING THE HYDRAULIC UNIT ABS 
OPERATION BY PRESSURE GAUGE

<Ref. to ABS-7, CHECKING THE HYDRAULIC
UNIT ABS OPERATION BY PRESSURE GAUGE,
INSPECTION, ABS Control Module and Hydraulic
Control Unit (ABSCM&H/U).>

2. CHECKING THE HYDRAULIC UNIT ABS 
OPERATION WITH THE BRAKE TESTER

<Ref. to ABS-8, CHECKING THE HYDRAULIC
UNIT ABS OPERATION WITH THE BRAKE
TESTER, INSPECTION, ABS Control Module and
Hydraulic Control Unit (ABSCM&H/U).>

3. CHECKING THE HYDRAULIC UNIT VDC 
OPERATION USING A PRESSURE GAUGE

1) Lift up the vehicle, and remove the wheels.
2) Remove the air bleeder screws from FL and FR
caliper bodies.
3) Connect two pressure gauges to FL and FR cal-
iper bodies.

CAUTION:
• Use a pressure gauge used exclusively for
brake fluid measurement.
• Do not use a pressure gauge used for the
measuring transmission oil pressure, as the
piston seal may expand and deform.

NOTE:
Wrap sealing tape around the pressure gauge.

4) Bleed air from the pressure gauge.
5) Perform VDC sequence control.
<Ref. to VDC-13, VDC Sequence Control.>
6) When the hydraulic unit begins to work, first the
FL side performs compression, hold, and decom-
pression, and then the FR side performs compres-
sion, hold, and decompression.
7) Read values indicated on the pressure gauge
and check if the fluctuation of the values between
decompression and compression meets specifica-
tion. Depress the brake pedal and check that it is
not abnormally hard, and tightness is normal.

8) Disconnect the pressure gauges from FL and FR
caliper bodies.
9) Install the air bleeder screws of FL and FR cali-
per bodies.
10) Remove the air bleeder screws from RL and
RR caliper bodies.
11) Connect two pressure gauges to RL and RR
caliper bodies.

(1) Identification mark

VDC00452

(1)

 

Front wheel

Rear wheel

When 
pressurized

3,000 kPa

(31 kgf/cm

2

, 441 psi)

or more

3,000 kPa

(31 kgf/cm

2

, 441 psi)

or more

When 
depressurized

500 kPa

(5 kgf/cm

2

, 73 psi)

or less

500 kPa

(5 kgf/cm

2

, 73 psi)

or less

ABS00134

VDC-9

VDC Control Module and Hydraulic Control Unit (VDCCM&H/U)

VEHICLE DYNAMICS CONTROL (VDC)

12) Bleed air from RL and RR caliper bodies, and
pressure gauge.
13) Perform VDC sequence control.
<Ref. to VDC-13, VDC Sequence Control.>
14) When the hydraulic unit begins to work, first the
RR side performs compression, hold, and decom-
pression, and then the RL side performs compres-
sion, hold, and decompression.
15) Read the values indicated on the pressure
gauges and check if it is within specification. De-
press the brake pedal and check that it is not abnor-
mally hard, and tightness is normal.
16) Disconnect the pressure gauge from the RL
and RR caliper bodies.
17) Install the air bleeder screws of RL and RR cal-
iper bodies.
18) Bleed air from the brake line.

4. CHECK HYDRAULIC UNIT VDC 
OPERATION WITH BRAKE TESTER

1) Set wheels other than the one to measure on
free rollers.
2) Prepare to operate the VDC sequence control.
<Ref. to VDC-13, VDC Sequence Control.>
3) Set the front wheels or rear wheels on the brake
tester and set the select lever position to the “N”
range.

4) Operate the brake tester.
5) Perform VDC sequence control.
<Ref. to VDC-13, VDC Sequence Control.>

6) When the hydraulic unit begins to work, check
the following work sequence.

(1) The FL wheel performs compression, hold
and decompression in sequence, and subse-
quently the FR wheel repeats the cycle.
(2) The RR wheel performs compression, hold
and decompression in sequence, and subse-
quently the RL wheel repeats the cycle.

7) Read values indicated on the brake tester and
check if the fluctuation of the values between de-
compression and compression meets specifica-
tion.

8) After the inspection, depress the brake pedal
and check that it is not abnormally hard, and tight-
ness is normal.

(1) Brake tester

ABS00136

(1)

ABS00137

(1)

 Front 

wheel

Rear 

wheel

When pressurized

2,000 N

(203 kgf, 447 lb)

or more

2,000 N

(203 kgf, 447 lb)

or more

When depressurized

500 N

(51 kgf, 112 lb)

or less

500 N

(51 kgf, 112 lb)

or less