1997 SUBARU LEGACY service

3. CONDITIONS FOR COMPLETION OF ABS
SEQUENCE CONTROL
When the following conditions develop, the ABS sequence
control stops and ABS and TCS warning lights come on
while the ABS and TCS function will then stop. The brake
system functions as a conventional brake system.
1) When the speed of at least one wheel reaches 10 km/h
(6 MPH).
2) When terminal No.4 is separated from ground. (When
select monitor is not used.)
3) When the brake pedal is released during sequence con-
trol and the braking lamp switch is set to off.
4) After completion of the sequence control.
5) When malfunction is detected.
NOTE:
When malfunction has been detected and the ABS
sequence control operation has stopped, the trouble codes
are stored in memory.
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4-4SERVICE PROCEDURE
20. Hydraulic Unit for ABS/TCS System

4. CONDITIONS FOR ABS SEQUENCE CONTROL
B4M0637A
NOTE:
When select monitor is used, control operation starts at
point A. It is not required to operate brake lamp switch for
starting ABS sequence control operation. The patterns
from IGN key ON to the point A show that operation is
started by diagnosis connector.
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4-4SERVICE PROCEDURE
20. Hydraulic Unit for ABS/TCS System

E: CHECKING THE HYDRAULIC UNIT TCS
OPERATION
1. CHECKING THE HYDRAULIC UNIT TCS
OPERATION BY PRESSURE GAUGE
1) Lift-up vehicle and remove wheels.
2) Disconnect the air bleeder screws from the FL and FR
caliper bodies.
B4M0633A
3) Connect two pressure gauges to the FL and FR caliper
bodies.
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.
NOTE:
Wrap sealing tape around the pressure gauge.
4) Bleed air from the pressure gauges.
5) Perform sequence control.
6) When the hydraulic unit begins to work, and first the FL
side performs compression, holding, and decompression,
and then the FR side performs compression, holding, and
decompression.
7) Read values indicated on the pressure gauge and
check if the fluctuation of the values between compression
and decompression meets the standard values. Also check
if any irregular brake pedal tightness is felt.
Initial value When compressed When decompressed
Front left wheel490 kPa (5 kg/cm
2, 71 psi)
or less1,471 kPa (15 kg/cm2, 213 psi)
or more490 kPa (5 kg/cm2, 71 psi)
or less
Front right wheel490 kPa (5 kg/cm
2, 71 psi)
or less1,471 kPa (15 kg/cm2, 213 psi)
or more490 kPa (5 kg/cm2, 71 psi)
or less
8) After checking, remove the pressure gauges from the
caliper bodies.
9) Connect the air bleeder screws to the FL and FR cali-
per bodies.
10) Bleed air from brake line.
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4-4SERVICE PROCEDURE
20. Hydraulic Unit for ABS/TCS System

2. CHECKING THE HYDRAULIC UNIT TCS
OPERATION WITH BRAKE TESTER
1) Prepare for operating TCS sequence control. 4-4 [W20F1] step 1 or 4-4 [W20F2] step 1.>
B4M0638
2) Set the front wheels on the brake tester and set the
select lever’s position at“neutral”.
3) Operate the brake tester.
4) Perform sequence control. [W20F2].>
5) Hydraulic unit begins to work; and check the following
working sequence.
The front left wheel performs compression, holding,
and decompression in sequence, and subsequently the
front right wheel repeats the cycle.
6) Read values indicated on the brake tester and check if
the fluctuation of values, when decompressed and
compressed, meet the standard values.
When compressed When decompressed
Front left wheel 981—1,471 N (100—150 kg, 221—331 lb) 245 N (25 kg, 55 lb) or less
Front right wheel 981—1,471 N (100—150 kg, 221—331 lb) 245 N (25 kg, 55 lb) or less
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4-4SERVICE PROCEDURE
20. Hydraulic Unit for ABS/TCS System

F: TCS SEQUENCE CONTROL
1) Under the TCS sequence control, after the hydraulic
unit solenoid valve is driven, the operation of the hydraulic
unit can be checked by means of the brake tester or pres-
sure gauge.
2) TCS sequence control can be started by diagnosis con-
nector or select monitor.
B4M0082C
1. OPERATIONAL GUIDELINES OF THE TCS
SEQUENCE CONTROL WITH DIAGNOSIS
CONNECTOR
1) Connect diagnosis terminals to terminal No. 4 of the
diagnosis connector beside driver seat heater unit.
2) Ignition switch is turned to ON.
3) Make sure only the start code (code 11) is shown in
normal condition.
NOTE:
When trouble codes are stored in memory, repair the faulty
parts.
4) Set the speed of all wheels at 10 km/h (6 MPH) or less.
5) Turn ignition switch OFF.
6) Start engine, and within 0.5 seconds after the ABS
warning light and TCS warning light go out, press TCS OFF
switch. Within 1.0 second thereafter, release and press the
switch again. Then, keep the switch pressed.
NOTE:

When the TCS sequence control is set to on, the brake
pedal must not be depressed.

Engine must operate.

When TCS OFF switch is not depressed within 0.5 sec-
onds after ABS and TCS warning lights turn off, the trouble
code mode comes on.
7) After completion of TCS sequence control, turn ignition
switch OFF.
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4-4SERVICE PROCEDURE
20. Hydraulic Unit for ABS/TCS System

2. OPERATIONAL GUIDELINES OF THE TCS
SEQUENCE CONTROL WITH SELECT MONITOR
1) Connect select monitor to data link connector beside
driver’s seat heater unit.
2) Engine starts.
3) Put select monitor to TCS mode.
4) Put select monitor to FBI mode. Make sure code 11 is
indicated.
NOTE:
When trouble codes are stored in memory, repair the faulty
parts.
B4M0639
5) Press FD2 ENT key.
B4M0624
6) When the message shown in the figure is displayed,
press ENT key.
7) Checked portions will be displayed on select monitor.
B4M0627
8) When TCS sequence control cannot be started (by sys-
tem malfunction, etc.), the message shown in the figure will
be displayed.
NOTE:
Read the trouble codes. Repair faulty parts.
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4-4SERVICE PROCEDURE
20. Hydraulic Unit for ABS/TCS System

3. CONDITIONS FOR COMPLETION OF TCS
SEQUENCE CONTROL
When the following conditions develop, the TCS sequence
control stops and ABS and TCS warning lights come on
while the ABS and TCS function will then stop. The brake
system functions as a conventional brake system.
1) When the speed of at least one wheel reaches 10 km/h
(6 MPH).
2) When terminal No. 4 is separated from ground. (When
select monitor is not used.)
3) When the brake pedal is depressed during sequence
control and the braking lamp switch is set to ON.
4) When TCS OFF switch is released. (When select moni-
tor is not used.)
5) After completion of the TCS sequence control.
6) When output signal to break TCS control is emitted from
ECM.
7) When malfunction is detected.
NOTE:
When malfunction has been detected and the TCS
sequence control operation has stopped, the trouble codes
are stored in memory.
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4-4SERVICE PROCEDURE
20. Hydraulic Unit for ABS/TCS System

4. CONDITIONS FOR TCS SEQUENCE CONTROL
B4M0642A
NOTE:
When select monitor is used, control operation starts at
point A. It is not required to operate TCS OFF switch for
starting control operation. The patterns from IGN key ON
to point A show operation is started by diagnosis connec-
tor.
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4-4SERVICE PROCEDURE
20. Hydraulic Unit for ABS/TCS System