Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 520

VDC-9

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

VEHICLE DYNAMICS CONTROL (VDC)

3) Connect the brake pipes to their correct VDC-

CM&H/U positions.
Tightening torque:

T1: 15 N·m (1.53 kgf-m, 11.1 ft-lb)

T2: 19 N·m (1.94 kgf-m, 14 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. <Ref. to BR-41,

PROCEDURE, Air Bleeding.>

6) Check the parameter to confirm that the applied

models and grades of the relevant vehicle are in-

cluded. <Ref. to VDC(diag)-21, PARAMETER

CHECK, OPERATION, Subaru Select Monitor.>

7) If the applied model and grade of the target ve-

hicle are not included on the {Confirm on parame-

ter} display screen, perform parameter selection

and registration. <Ref. to VDC(diag)-21, PARAME-

TER SELECTION, OPERATION, Subaru Select

Monitor.>
NOTE:

• When the VDCCM&H/U is replaced with a new

part, be sure to perform the selection · registration

operation.

• For the selection and registration of parameter,

the Subaru Select Monitor is required.

• When the registration has not been performed,

the DTC code “Parameter selection error” is detect-

ed together with the ABS/EBD/VDC warning light il-

lumination.

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 identification mark.

<Ref. to VDC-2, SPECIFICATION, General De-

scription.>

1. CHECKING THE HYDRAULIC UNIT ABS

OPERATION BY PRESSURE GAUGE

1) Lift up the vehicle, and then remove the wheel.

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 the pressure gauge used for the

measurement of transmission oil. Doing so will

cause the piston seal to expand and deform.
NOTE:

Wrap sealing tape around the pressure gauge.

VDC00451

T1

T2

(1) Identification mark

VDC00452

(1)

ABS00134

VDC-10

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

VEHICLE DYNAMICS CONTROL (VDC)

4) Bleed air from the pressure gauges and the FL

and FR caliper bodies.

5) Perform ABS sequence control. <Ref. to VDC-

14, ABS Sequence Control.>

6) When the hydraulic unit begins to work, first the

FL side performs decompression, hold and com-

pression, and then the FR side performs decom-

pression, hold and compression.

7) Read values indicated on the pressure gauge

and check if the fluctuation of the values between

decompression and compression meets the stan-

dard values. Depress the brake pedal and check

that the kick-back is normal, and tightness is nor-

mal.

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.

12) Bleed air from the brake system. <Ref. to BR-

41, PROCEDURE, Air Bleeding.>

13) Bleed air from RL and RR caliper bodies, and

pressure gauge.

14) Perform ABS sequence control. <Ref. to VDC-

14, ABS Sequence Control.>

15) When the hydraulic unit begins to work, first the

RR side performs decompression, hold and com-

pression, and then the RL side performs decom-

pression, hold and compression.

16) 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 the

kick-back is normal, and tightness is normal.

17) Disconnect the pressure gauge from the RL

and RR caliper bodies.

18) Install the air bleeder screws of RL and RR cal-

iper bodies.

19) Bleed air from the brake system. <Ref. to BR-

41, PROCEDURE, Air Bleeding.>

2. CHECKING THE HYDRAULIC UNIT ABS

OPERATION WITH THE BRAKE TESTER

1) Set wheels other than the one to measure on

free rollers.

2) Prepare for ABS sequence control. <Ref. to

VDC-14, ABS Sequence Control.>

3) Set the front wheels or rear wheels on the brake

tester and set the gear to “neutral”.

4) Operate the brake tester.

5) Perform ABS sequence control. <Ref. to VDC-

14, ABS Sequence Control.>

6) When the hydraulic unit begins to work, check

the following work sequence.

(1) The FL wheel performs decompression,

hold and compression in sequence, and subse-

quently the FR wheel repeats the cycle.

(2) The RR wheel performs decompression,

hold and compression 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.

Front wheel

Rear wheel

Initial value

3,500 kPa

(36 kgf/cm

2

, 511

psi)

3,500 kPa

(36 kgf/cm

2

, 511

psi)

When depres-

surized

500 kPa

(5 kgf/cm

2

, 73 psi)

or less

500 kPa

(5 kgf/cm

2

, 73 psi)

or less

When pressur-

ized

3,500 kPa

(36 kgf/cm

2

, 511

psi)

or more

3,500 kPa

(36 kgf/cm

2

, 511

psi)

or more

(1) Brake tester

Front wheel

Rear wheel

Initial value

1,000 N

(102 kgf, 225 lbf)

1,000 N

(102 kgf, 225 lbf)

When depressurized

500 N

(51 kgf, 112 lbf)

or less

500 N

(51 kgf, 112 lbf)

or less

When pressurized

1,000 N

(102 kgf, 225 lbf)

or more

1,000 N

(102 kgf, 225 lbf)

or more

ABS00136

(1)

ABS00137

(1)

VDC-11

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

VEHICLE DYNAMICS CONTROL (VDC)

8) After the inspection, depress the brake pedal

and check that it is not abnormally hard, and tight-

ness is normal.

3. CHECKING THE HYDRAULIC UNIT VDC

OPERATION USING A PRESSURE GAUGE

1) Lift up the vehicle, and then remove the wheel.

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-

17, 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.

12) Bleed air from RL and RR caliper bodies, and

pressure gauge.

13) Perform VDC sequence control. <Ref. to VDC-

17, 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 system. <Ref. to BR-

41, PROCEDURE, Air Bleeding.>

4. CHECK HYDRAULIC UNIT VDC OPERA-

TION 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-17, VDC Sequence Control.>

3) Set the front wheels or rear wheels on the brake

tester and set the gear to neutral.

Front wheel

Rear wheel

When pres-

surized

3,000 kPa

(31 kgf/cm

2

, 441

psi)

or more

3,000 kPa

(31 kgf/cm

2

, 441

psi)

or more

When depres-

surized

500 kPa

(5 kgf/cm

2

, 73 psi)

or less

500 kPa

(5 kgf/cm

2

, 73 psi)

or less

ABS00134

(1) Brake tester

ABS00136

(1)

ABS00137

(1)

VDC-12

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

VEHICLE DYNAMICS CONTROL (VDC)

4) Operate the brake tester.

5) Perform VDC sequence control. <Ref. to VDC-

17, 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.

D: REPLACEMENT

CAUTION:

• Because the pressure sensor built into the H/

U is easily damaged by static electricity, start

the operation after performing static electricity

measures.

• Be careful not to touch the sensors in the H/U

to prevent damage.

• Because the seal of the VDCCM cannot be re-

placed, do not pull or peel it by lifting it up.

• Because the screw of the H/U will become

slightly worn in every replacement procedure, 5

times is the maximum number of times for re-

placement. If a problem is found such as not

being able to torque the screw to specifications

even before 5 replacement operations are per-

formed, replace the H/U body.

• When installing the VDCCM, always use new

screws.

• When the sealing surface of the VDCCM or H/

U is dirty or damaged and it cannot be cleaned

or repaired, replace with a new part.

1) Remove the VDCCM&H/U. <Ref. to VDC-8, RE-

MOVAL, VDC Control Module and Hydraulic Con-

trol Unit (VDCCM&H/U).>

2) To prevent entry of foreign objects and brake flu-

id leakage, plug the oil pressure port of the VDC-

CM&H/U using a screw plug, etc.

3) Set the pump motor section of the removed VD-

CCM&H/U face down on a vise.
NOTE:

Before securing a part on a vise, place cushioning

material such as wood blocks, aluminum plate, or

cloth between the part and the vise.

4) Using TORX

®

bit E5, remove the four screws of

VDCCM.
NOTE:

Do not re-use the screws.

5) Slowly pull out the VDCCM upward from the H/

U.
NOTE:

To prevent damaging of coil section, remove the

VDCCM straight up from H/U without twisting.

6) Make sure there is no dirt or damage on the seal-

ing surface of the H/U.
CAUTION:

• Do not clean the VDCCM&H/U by applying

compressed air.

• Even if damage is found on the H/U seal, do

not attempt repair by filing or with a metal

scraper. To remove the seal residue, always

use a plastic scraper. Do not use chemical such

as paint thinner, etc., to clean.

7) Position the coil of the new VDCCM to align with

the H/U valve.

8) To prevent deformation of the VDCCM housing

cover, hold the corner of VDCCM and install it to

the H/U without tilting.

Front wheel

Rear wheel

When pressurized

2,000 N

(204 kgf, 450 lbf)

or more

2,000 N

(204 kgf, 450 lbf)

or more

When depressur-

ized

500 N

(51 kgf, 112 lbf)

or less

500 N

(51 kgf, 112 lbf)

or less

(1) Aluminum plate, etc.
(2) Vise

ABS00430

(1)

(2)

ABS00431