1995 SUBARU LEGACY engine

5. Control Module I/O Signal
1. I/O SIGNAL VOLTAGE
G4M0685
ContentsTerminal
No.Ignition
switch ON,
engine
OFFInput/output signals
Measured value Measuring conditions
A.B.S.
sensorFront left wheel 22
0 V 0.12—1V
No. 22—No. 4
(When it is 10 Hz.)
GND 4
Front right wheel 23
0 V 0.12—1V
No. 23—No. 21
(When it is 10 Hz.)
GND 21
Rear left wheel 8
0 V 0.12—1V
No. 8—No. 9
(When it is 10 Hz.)
GND 9
Rear right wheel 24
0 V 0.12—1V
No. 24—No. 26
(When it is 10 Hz.)
GND 26
G sensor (AWD MT model) 13 10—12 V 0 V When slanting about 14°—21.3°(θ)
Diagnosis connector30
—— —
31
Stop light switch 25 0 V 10—12 V When brake pedal is depressed.
Motor monitoring 14 0 V 10—12 V When motor operates.
Valve power supply monitoring 32 10—12 V 10—12 V Ignition switch ON*1
Hydraulic
control
unitSolenoidFront left
wheel210—12 V 0 V
When solenoid is energized to
produce output. Front right
wheel35 10—12 V 0 V
Rear wheel 18 10—12 V 0 V
Valve relay coil 27 0 V 0 V Ignition switch ON*2
Motor relay coil 28 10—12 V 0 VWhen motor operates to produce
output.
Warning light 29 10—12 V 10—12 V Ignition switch ON*3
Power
supplyIgnition 1 10—12 V 10—12 V Ignition switch ON
Relay coil (valve,
motor, etc.)17 10—12 V 10—12 V Ignition switch ON
Grounding line10 0V 0V—
20 0V 0V—
34 0V 0V—
*1: When ignition switch is OFF or the A.B.S. system is inactive: 0 V
*2: When ignition switch is OFF or the A.B.S. system is inactive: 10—12 V
*3: When ignition switch is OFF or the A.B.S. system is inactive, or during 1.5 seconds from ignition switch ON: 0 V
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5. Control Module I/O Signal

8. General Diagnostics Chart
A: VIBRATING PEDAL AND NOISE
Depress brake pedal
abruptly to check if
such problems occur
while A.B.S. is in
operation.
Ye s
No
Normal
When do problems
occur?When engine
starts.Check using on-board diagnosis system accord-
ing to trouble code.
Before vehicle
attains initial 10
km/h (6 MPH)
speed immediately
after engine starts.Do problems stop
within 5 seconds?
No
Ye s
Normal
Go to1.


Only when vehicle
is being driven.

Brake pedal is
released.
A.B.S. sometimes operates when variations in
wheel rotating speed occur:
a. During shifts. (AT model: Band brake locks
wheels. MT model: Abrupt engine brake opera-
tion locks wheels.)
b. During clutch operation. (Engine brake opera-
tion locks wheels.)
c. When riding over an obstacle.
d. During rough-road driving.
e. During“U”turns. (“Slip”signal often is emit-
ted.)
f. When wheels are stuck.
Except for those out-
lined above.Go to1.

Brake pedal is
depressed.
A.B.S. sometimes
operates except when
brake pedal is
depressed abruptly:
a. Low“µ”roads.
b.“U”turns during
high-speed operations.
c. During rough-road
driving.
d. When tire chains
are installed.
e. Use of improper
tires.
f. Excessive free play
of wheels and associ-
ated parts.Check tire pres-
sure.
(Premature wear
may occur if tires
other than those
specified are
used.)
a. Use specified
tires.
b. Adjust tire pres-
sure evenly.
c. Use of an
“emergency”tire.
d. Check wheels
and associated
parts if excessive
free play is noted.
1Except for those
outlined above.Go to1.

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8. General Diagnostics Chart

3. Electrical Components Location
B4M0373A
1Hydraulic control unit

2Engine control module

3AT control module

4TCS warning light

5ABS warning light

6Diagnosis connector

7TCS operating indicator light

8TCS OFF indicator light
9TCS OFF switch

10Data link connector (for Subaru select monitor)

11Data link connector (for Subaru select monitor and OBD-II
general scan tool)

12Tone wheel

13ABS sensor

14Stroke sensor

15ABS/TCS control module
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3. Electrical Components Location

4. Schematic
B4M0380A
1Hydraulic control unit

2Valve relay

3Motor relay

4Motor

5Motor sensor

6Front left inlet solenoid valve

7Front left outlet solenoid valve

8Rear right inlet solenoid valve

9Rear right outlet solenoid valve

10TCS solenoid valve 2

11Front right inlet solenoid valve

12Front right outlet solenoid valve

13Rear left inlet solenoid valve
14Rear left outlet solenoid valve

15TCS solenoid valve 1

16Pressure switch

17Data link connector

18ABS/TCS control module

19ABS warning light

20TCS operating indicator light

21TCS OFF indicator light

22TCS warning light

23Stroke sensor

24TCS OFF switch

25Diagnosis connector
26Engine control module

27Rear right ABS sensor

28Front right ABS sensor

29Front left ABS sensor

30Rear left ABS sensor

31Brake warning light

32Parking brake switch

33Brake fluid level sensor

34Generator

35Stop lamp switch

36Stop lamp

37AT control module
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4. Schematic

Contents Connector No. Terminal No.Input/Output signals
Measured value and measuring conditions
TCS
control
unit ECM
commun-
icationTCS,ECM communication
(torque command)P6 14—GNDLess than 0.7 V when the vehicle stands
still.
TCS,ECM communication
(torque command)P6 5—GNDLess than 5 V when the vehicle stands
still.
TCS,ECM communication
(TCS operates)P6 12—GND4—5.4 V when TCS controls no
operations. Less than 0.7 V when it
controls operations.
ECM,TCS communication
(engine control)P6 4—GNDH/L toggle signal with the accelerator
pedal off (Cycle 20 mS, H: 10—14 V, L:
less than 0.7 V). Less than 2.0 V with the
accelerator pedal depressed. Also when
TCS OFF indicator light comes on by TCS
OFF switch.
ABS operation signal P6 13—GND10—14 V when the ABS control does not
operate still and less than 0.7 V when
ABS operates.
Fluid level sensor P7 20—GNDLess than2VwhenIGNisONand10—
14 V when idling.
Select
monitorData is received. P7 9—GND 4—4.5 V when no data is received.
Data is sent. P7 19—GND 4—4.5 V when no data is sent.
Diagnosis connector P7 8—GND 10—14 V when IGN is ON.
Power
supplyIgnition P5 1—GND 10—14 V when IGN is ON.
Battery P5 4—GND 10—14 V
Grounding
linePower P5 5—body 1Ωor less
Digital P7 15—body 1Ωor less
Power P4 6—body 1Ωor less
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5. Control Module I/O Signal

B: CHECK LIST FOR INTERVIEW
Check the following items about the vehicle’s state.
1. THE STATE OF THE WARNING LIGHTS
a. ABS warning light

1Is always on.2Sometimes comes on.3Comes on only once.4Does not come on.
When/how long does it come on?
Ignition key
position
1Lock2Acc3On (before starting engine)4Start5On after starting (Engine: run)
6On after starting (Engine: stop)
Timing
1Immediately after ignition is on.2Immediately after ignition starts.
3When advancing (Speedmiles/h,miles/h)4While traveling at a constant speed (Speedmiles/h)
5When decelerating (Speedmiles/h,miles/h)
6When turning (To right, to left, steering angledeg., steering timesec)
7When other electrical parts move (Part name:, Operating condition)
8When moving other electrical parts (Part name:, Operating condition)
b. TCS warning light

1Is always on.2Sometimes comes on.3Comes on only once.4Does not come on.
When does it come on?
Ignition key
position
1Lock2Acc3On (before starting engine)4Start5On after starting (Engine: run)
6On after starting (Engine: stop)
Timing
1Immediately after ignition is on.2Immediately after ignition starts.
3When advancing (Speedmiles/h,miles/h)4While traveling at a constant speed (Speedmiles/h)
5When decelerating (Speedmiles/h,miles/h)
6When turning (To right, to left, steering angledeg., steering timesec)
7When other electrical parts move (Part name:, Operating condition)
8When moving other electrical parts (Part name:, Operating condition)
c. TCS OFF indicator light

1Is always on.2Sometimes comes on.3Comes on only once.4Does not come on.
When/how long does it come on?
Ignition key
position
1Lock2Acc3On (before starting engine)4Start5On after starting (Engine: run)
6On after starting (Engine: stop)
Timing
1Immediately after ignition is on.2Immediately after ignition starts.
3When advancing (Speedmiles/h,miles/h)4While traveling at a constant speed (Speedmiles/h)
5When decelerating (Speedmiles/h,miles/h)
6When turning (To right, to left, steering angledeg., steering timesec)
7When other electrical parts move (Part name:, Operating condition)
8When moving other electrical parts (Part name:, Operating condition)
d. TCS operation indicator light

1Is always on.2Sometimes comes on.3Comes on only once.4Does not come on.
When does it come on?
Ignition key
position
1Lock2Acc3On (before starting engine)4Start5On after starting (Engine: run)
6On after starting (Engine: stop)
Timing
1Immediately after ignition is on.2Immediately after ignition starts.
3When advancing (Speedmiles/h,miles/h)4While traveling at a constant speed (Speedmiles/h)
5When decelerating (Speedmiles/h,miles/h)
6When turning (To right, to left, steering angledeg., steering timesec)
7When other electrical parts move (Part name:, Operating condition)
8When moving other electrical parts (Part name:, Operating condition)
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6. Diagnostics Chart for On-board Diagnosis System

e. Malfunction indicator light

1Is always on.2Sometimes comes on.3Comes on only once.4Does not come on.
When does it come on?
Ignition key
position
1Lock2Acc3On (before starting engine)4Start5On after starting (Engine: run)
6On after starting (Engine: stop)
Timing
1Immediately after ignition is on.2Immediately after ignition starts.
3When advancing (Speedmiles/h,miles/h)4While traveling at a constant speed (Speedmiles/h)
5When decelerating (Speedmiles/h,miles/h)
6When turning (To right, to left, steering angledeg., steering timesec)
7When other electrical parts move (Part name:, Operating condition)
8When moving other electrical parts (Part name:, Operating condition)
2. SYMPTOMS
ABS operating
condition1Performs no work.2Operates only when abruptly applying brakes. (Conditions: vehicle speedmiles/h, how to step
on brake pedal)
3Operating time (sec., etc.)4Operating noise (Produced/Not produced)
5What kind of noise? (Knock, gong gong, bong, buzz, gong gong buzz, etc.)
6Reaction force of brake pedal (Stick, pressed down once with a clunk, pressed and released, etc.)
TCS operating
condition
1Performs no work.2Operates only when abruptly accelerating. (Conditions: vehicle speedmiles/h, how to step on
accelerator pedal)
3Operating time (sec., etc.)4Operating noise (Produced/Not produced)
5What kind of noise? (Knock, gong gong, bong, buzz, gong gong buzz, etc.)
6Whether or not operation indicator light comes on. (Come on/Does not come on, Others)
Behavior of
vehicle
1Directional stability cannot be obtained or steering arm refuses to work when applying brakes (vehicle turns to right, turns
to left, spins, etc.).
2Directional stability cannot be obtained or steering arm refuses to work when accelerating (vehicle turns to right, turns to
left, spins, etc.).
3Brakes are out of order (braking distance is long, brakes lock or drag, pedal stroke is long, pedal sticks, etc.).
4Poor acceleration (fails to accelerate, engine stalls, etc.).
5Vibration, abnormal noise (operating noise is loud, noise is produced during operation from the front of vehicle (right, left)
(tones:), noise is produced during operation from the rear of vehicle (tones:, others)
6Other phenomena (concrete symptoms)
3. CONDITIONS UNDER WHICH TROUBLE OCCURS
Environment1Weather (fine, cloudy, rain, snow, etc.)
2Ambient temperature (°C/°F)
3Road (urban area, suburbs, highway, general road, ascending slope, descending slope, paved road, gravel road, muddy
road, sandy place, etc.)
4Road surface (dry, wet, new-fallen snow, compressed snow, frozen slope, etc.)
Conditions
1Brakes (decelerationg, continuous/intermittent)2Accelerator (accelerationg, continuous/intermittent)
3Travel speed (miles, advancing, accelerating, reducing speed, low speed, turning, etc.)
4Condition of tire of each wheel (air pressure, degree of wear, whether or not genuine parts are used, whether
or not chain is passed around tires, whether or not T tire is used.) others ()
5Condition of suspension alignment ()
6Loading state ()
4. REPAIRED PARTS ARE USED OR NOT
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6. Diagnostics Chart for On-board Diagnosis System

7. Diagnostics Chart for Warning Light
Circuit Failure
A: TROUBLE CODE DOES NOT APPEAR.
—TCS WARNING LIGHT COMES ON WHEN
STARTING THE ENGINE.—
1. Check TCS warning light.
OK
Not OK
Repair harness.
2. Check diagnosis terminal.
OK
Not OK
Repair harness.
3. Check diagnosis connector.
OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.
B4M0385



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7. Diagnostics Chart for Warning Light Circuit Failure