1995 SUBARU LEGACY Control unit

15. Hydraulic Unit for ABS System
B4M0069A
1Connector

2Cap

3Motor relay

4Valve relay

5Hydraulic control unit

6Front-RH outlet

7Rear-LH outlet
8Rear-RH outlet

9Front-LH outlet

10Primary inlet

11Secondary inlet

12Bracket
Tightening torque: N⋅m (kg-m, ft-lb)
T1: 1.2±0.2
(0.125±0.025, 0.9±0.2)
T2: 18±5 (1.8±0.5, 13.0±3.6)
T3: 29±7 (3.0±0.7, 21.7±5.1)
T4: 32±10 (3.3±1.0, 24±7)
A: REMOVAL
1) Remove air intake duct.
2) Remove canister from engine compartment to facilitate
removal of hydraulic unit.
3) Disconnect brake pipes from hydraulic unit and plug
open joints to prevent entry of foreign particles.
G4M0455
4) Remove nuts and bolts which secure hydraulic unit, and
remove hydraulic unit from engine compartment.
CAUTION:

Hydraulic unit cannot be disassembled. Do not
attempt to loosen bolts and nuts.

Do not drop or bump hydraulic unit.

Do not turn the hydraulic unit upside down or place
it on its side.
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15. Hydraulic Unit for ABS System

2. CHECKING THE HYDRAULIC UNIT OPERATION BY
PRESSURE GAUGE
1) Remove the FL and FR pipes from the hydraulic unit.
G4M0460
2) Connect two pressure gauges to the hydraulic unit.
CAUTION:

Pressure gauges used exclusively for brake fluid
must be used.

Do not employ pressure gauge previously used for
transmission since the piston seal is expanded which
may lead to malfunction of the brake.
3) Bleed air from the pressure gauges.
4) Perform sequence control.
B4M0082A
(1) Connect diagnosis terminals to 3 terminals (K) and
6 terminals (L) of the diagnosis connector beside driver
seat heater unit.
(2) Turn ignition switch ON.
(3) The ABS warning light comes on.
(4) Depress the brake pedal within 0.5 seconds after
the warning light goes out so that the pressure gauge
registers a pressure equal to the initial value.
CAUTION:
Do not depress the clutch pedal.
NOTE:
The engine must not be operating.
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15. Hydraulic Unit for ABS System

G4M0462
3. CHECKING THE HYDRAULIC UNIT WITH BRAKE
TESTER
1) In the case of AWD vehicles, install a spare fuse with
the FWD connector in the engine compartment to simulate
FWD vehicles.
B4M0082A
2) Connect diagnosis terminals to 3 terminals (K) and 6
terminals (L) of the diagnosis connector beside driver seat
heater unit.
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3) Set the front wheels or rear wheels on the brake tester
and set the select lever’s position at“neutral”.
4) Operate the brake tester.
5) Perform sequence control.
(1) Turn ignition switch ON.
(2) The ABS warning light comes on.
(3) Depress the brake pedal within 0.5 seconds after
the warning light goes out so that the brake tester reg-
isters a pressure equal to the initial value.
CAUTION:
Do not depress the clutch pedal.
NOTE:
The engine must not be operating.
6) Hydraulic unit begins to work; and check the following
working sequence.
(1) The left front wheel performs decompression,
holding, and compression in sequence, and subse-
quently the right front wheel repeats the cycle.
(2) Simultaneously both right and left rear wheel per-
form decompression, holding, and compression in
sequence.
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15. Hydraulic Unit for ABS System

7) Read values indicated on the brake tester and check if
the fluctuation of values, when decompressed and
compressed, meet the standard values.
Initial value When decompressed When compressed
Front wheel 1,961 N (200 kg, 441 lb) 245 N (25 kg, 55 lb) 1,961 N (200 kg, 441 lb)
Rear wheel 686 N (70 kg, 154 lb) 245 N (25 kg, 55 lb) 686 N (70 kg, 154 lb)

In case of hydraulic unit plunger piston malfunction:
Initial value When decompressed When compressed
Rear right wheel 686 N (70 kg, 154 lb) 245 N (25 kg, 55 lb) 686 N (70 kg, 154 lb)
Rear left wheel 686 N (70 kg, 154 lb) 686 N (70 kg, 154 lb) 686 N (70 kg, 154 lb)
8) After checking, also check if any irregular brake pedal
tightness is felt.
9) In case of AWD vehicles, remove the spare fuse from
the FWD connector in the engine compartment to return to
the original AWD state.
C: SEQUENCE CONTROL
Under the sequence control, after the hydraulic unit sole-
noid valve is driven, the operation of the hydraulic unit can
be checked by means of the brake tester or pressure
gauge.
B4M0082A
1. OPERATIONAL GUIDELINES OF THE SEQUENCE
CONTROL
1) Connect diagnosis terminals to 3 terminals (K) and 6
terminals (L) of the diagnosis connector beside driver seat
heater unit.
2) Set the speed of all wheels at 4 km/h (2 MPH) or less.
3) Within 0.5 seconds after the ABS warning lamp goes
out, immediately after the ignition switch is turned to on,
depress the brake pedal and hold.
CAUTION:
Do not depress the clutch pedal.
NOTE:

When the ignition switch is set to on, the brake pedal
must not be depressed.

Engine must not operate.
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15. Hydraulic Unit for ABS System

2. CONDITIONS FOR COMPLETION OF SEQUENCE
CONTROL
1) When the speed of at least one wheel reaches 10 km/h
(6 MPH), the operation is returned to the normal control
mode.
2) When L terminal is separated from ground, the opera-
tion is returned to the normal control mode.
3) When K terminal is separated from ground, the opera-
tion goes to the trouble code display mode.
4) When the brake pedal is released during sequence con-
trol and the braking lamp switch is set to off, the operation
is returned to the normal control mode.
5) After completion of the sequence control, the operation
is returned to the normal control mode.
B4M0116A
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15. Hydraulic Unit for ABS System

G4M0455
D: INSTALLATION
1) Install relay box cover on hydraulic unit.
2) Install hydraulic unit to bracket.
Tightening torque:
18±5 N⋅m (1.8±0.5 kg-m, 13.0±3.6 ft-lb)
3) Tighten bracket and motor ground lead as a unit.
Tightening torque:
32±10 N⋅m (3.3±1.0 kg-m, 24±7 ft-lb)
4) Connect brake pipes to their correct hydraulic unit con-
nections.
Tightening torque:
15
+3
2N⋅m (1.5+0.3
0.2kg-m, 10.8+2.2
1.4ft-lb)
16. ABS Control Module
A: REMOVAL
1) Remove floor mat located under lower right side of front
seat.
G4M0468
2) Remove screw which secure ABS control module from
the body.
G4M0469
3) Disconnect connector from ABS control module.
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15. Hydraulic Unit for ABS System - 16. ABS Control Module

G4M0455
D: INSTALLATION
1) Install relay box cover on hydraulic unit.
2) Install hydraulic unit to bracket.
Tightening torque:
18±5 N⋅m (1.8±0.5 kg-m, 13.0±3.6 ft-lb)
3) Tighten bracket and motor ground lead as a unit.
Tightening torque:
32±10 N⋅m (3.3±1.0 kg-m, 24±7 ft-lb)
4) Connect brake pipes to their correct hydraulic unit con-
nections.
Tightening torque:
15
+3
2N⋅m (1.5+0.3
0.2kg-m, 10.8+2.2
1.4ft-lb)
16. ABS Control Module
A: REMOVAL
1) Remove floor mat located under lower right side of front
seat.
G4M0468
2) Remove screw which secure ABS control module from
the body.
G4M0469
3) Disconnect connector from ABS control module.
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15. Hydraulic Unit for ABS System - 16. ABS Control Module

19. Air Bleeding (With TCS model)
A: RULES FOR EFFECTIVE BLEEDING
1) Pressure is not applied to suction pipe by depressing
brake pedal. When any of the following are performed,
bleed air from suction pipe by air bleeding control opera-
tion.
NOTE:
For TCS vehicle, suction pipe is installed between master
cylinder and hydraulic unit to allow flow of brake fluid
between them during ABS and TCS operation.
(1) When brake pipe is disconnected from master cyl-
inder.
(2) When brake pipe between hydraulic unit and mas-
ter cylinder is disconnected.
(3) When fluid is emptied from reservoir tank.
2) The time interval between two brake pedal operations
(from the time when the pedal is released to the time when
it is depressed another time) shall be approximately 3 sec-
onds.
3) The air bleeder on each brake shall be released for 1
to 2 seconds.
B: BLEEDING PROCEDURE WITH AIR
BLEEDING CONTROL
1. BLEEDING PROCEDURE
CAUTION:

The FMVSS No. 116, fresh DOT3 or 4 brake fluid
must be used.

Cover bleeder with waste cloth, when loosening it,
to prevent brake fluid from being splashed over sur-
rounding parts.

Avoid mixing different brands of brake fluid to pre-
vent degrading the quality of the fluid.

Be careful not to allow dirt or dust to get into the
reservoir tank.

During bleeding operation, keep the brake reserve
tank filled with brake fluid to eliminate entry of air.
NOTE:

Brake pedal operating must be very slow.

For convenience and safety, it is advisable to have two
man working.
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1) Start air bleeding control operation. [W19D0].>
2) Make sure that there is no leak from joints and connec-
tions of the brake system.
3) Bleed air through front RH caliper by operating brake
pedal.
(1) Fit one end of vinyl tube into the air bleeder and put
the other end into a brake fluid container.
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19. Air Bleeding (With TCS model)