1997 SUBARU LEGACY ABS

4. Schematic
B4M1227A
1ABS control module and hydraulic control unit
(ABSCM&H/U)

2ABS control module area

3Valve relay

4Motor relay

5Motor

6Front left inlet solenoid valve

7Front left outlet solenoid valve

8Front right inlet solenoid valve

9Front right outlet solenoid valve

10Rear left inlet solenoid valve

11Rear left outlet solenoid valve

12Rear right inlet solenoid valve
13Rear right outlet solenoid valve

14Transmission control module (only AT model)

15Diagnosis connector

16Data link connector

17ABS warning light

18Stop light switch

19Stop light

20G sensor (only AWD model)

21Front left ABS sensor

22Front right ABS sensor

23Rear left ABS sensor

24Rear right ABS sensor
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4-4dBRAKES [ABS 5.3i TYPE]
4. Schematic

5. Control Module I/O Signal
1. I/O SIGNAL VOLTAGE
B4M1228A
NOTE:

The terminal numbers in the ABS control module and
hydraulic control unit connector are as shown in the figure.

When the connector is removed from the ABSCM&H/U,
the connector switch closes the circuit between terminal
No. 21 and No. 23. The ABS warning light illuminates.
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4-4dBRAKES [ABS 5.3i TYPE]
5. Control Module I/O Signal

ContentsTerminal No.
(+)—()Input/Output signal
Measured value and measuring conditions
ABS
sensor*2
(Wheel
speed
sensor)Front left wheel 9—10
0.12 — 1 V
(When it is 20 Hz.) Front right wheel 11—12
Rear left wheel 7—8
Rear right wheel 14—15
Valve relay power supply 24—23 10 — 15 V when ignition switch is ON.
Motor relay power supply 25—23 10 — 15 V when ignition switch is ON.
G sensor*2
(AWD
model only)power supply 30—28 4.75 — 5.25 V
ground 28 —
output 6—28 2.3±0.2 V when vehicle is in horizontal position.
Stop light switch*1 2—23Less than 1.5 V when the stop light is OFF and, 10 — 15 V
when the stop light is ON.
ABS warning light*2 21—23Less than 1.5 V during 1.5 seconds when ignition switch is
ON, and 10 — 15 V after 1.5 seconds.
AT ABS signal*2
(AT model only)31—23Less than 1.5 V when the ABS control does not operate still
and more than 5.5 V when ABS operates.
ABS operation signal monitor*2 3—23Less than 1.5 V when the ABS control does not operate still
and more than 5.5 V when ABS operates.
Select
monitor*2Data is received. 20—23 Less than 1.5 V when no data is received.
Data is sent. 5—23 4.75 — 5.25 V when no data is sent.
ABS
diagnosis
connector*2Terminal No. 3 29—23 10 — 15 V when ignition switch is ON.
Terminal No. 6 4—23 10 — 15 V when ignition switch is ON.
Power supply*1 1—23 10 — 15 V when ignition switch is ON.
Grounding line 23 —
Grounding line 26 —
*1: Measure the I/O signal voltage after removing the connector from the ABSCM&H/U terminal.
*2: Measure the I/O signal voltage at connector (F2) or (F1).
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4-4dBRAKES [ABS 5.3i TYPE]
5. Control Module I/O Signal

2. I/O SIGNAL DIAGRAM
B4M1229A
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4-4dBRAKES [ABS 5.3i TYPE]
5. Control Module I/O Signal

6. Diagnostics Chart for On-board
Diagnosis System
A: BASIC DIAGNOSTICS PROCEDURE
B4M1051A
CAUTION:
Remove foreign matter (dust, water, etc.) from the
ABSCM&H/U connector during removal and installa-
tion.
NOTE:

To check harness for broken wires or short circuits,
shake it while holding it or the connector.
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4-4dBRAKES [ABS 5.3i TYPE]
6. Diagnostics Chart for On-board Diagnosis System

When ABS warning light illuminates, read and record
trouble code indicated by ABS warning light.
B: CHECK LIST FOR INTERVIEW
Check the following items about the vehicle’s state.
1. THE STATE OF THE ABS WARNING LIGHT
ABS warning light
comes on.Always
Sometimes
Only once
Does not come on

When /how long does it come on?:
Ignition key positionLOCK
ACC
ON (before starting engine)
START
On after starting (Engine is running)
On after starting (Engine is stop)
TimingImmediately after ignition is ON.
Immediately after ignition starts.
When advancing km/h to km/h
MPH to MPH
While traveling at a constant speed km/h MPH
When decelerating km/h to km/h
MPH to MPH
When turning to right Steering angle : deg
Steering time : sec
When turning to left Steering angle : deg
Steering time : sec
When moving other electrical parts

Parts name :

Operating condition :
2. SYMPTOMS
ABS operating
conditionPerforms no work.
Operates only when abruptly applying brakes. Vehicle speed : km/h
MPH

How to step on brake pedal :
a) Operating time :sec
b) Operating noise :Produce /Does not produce

What kind of noise?Knock
Gong gong
Bong
Buzz
Gong gong buzz
Others :
c) Reaction force of brake pedal
Stick
Press down once with a clunk
Press and released
Others :
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4-4dBRAKES [ABS 5.3i TYPE]
6. Diagnostics Chart for On-board Diagnosis System

Behavior of vehicle a) Directional stability cannot be obtained or steering arm refuses to work when applying brakes :
Ye s /No

When :Vehicle turns to right
Vehicle turns to left
Spins
Others :
b) Directional stability cannot be obtained or steering arm refuses to work when accelerating :
Ye s /No

When :Vehicle turns to right
Vehicle turns to left
Spins
Others :
c) Brakes are out of order :Ye s /No

What :Braking distance is long
Brakes lock or drag
Pedal stroke is long
Pedal sticks
Others :
d) Poor acceleration :Ye s /No

What :Fails to accelerate
Engine stalls
Others :
e) Occurrence of vibration :Ye s /No

Where

What kind :
f) Occurrence of abnormal noise :Ye s /No

Where

What kind :
g) Occurrence of other phenomena :Ye s /No

What kind :
3. CONDITIONS UNDER WHICH TROUBLE OCCURS
Environment a) WeatherFine
Cloudy
Rainy
Snowy
Various/Others :
b) Ambient temperatureF(°C)
c) RoadUrban area
Suburbs
Highway
General road
Ascending slope
Descending slope
Paved road
Gravel road
Muddy road
Sandy place
Others :
d) Road surfaceDry
Wet
New-fallen snow
Compressed snow
Frozen slope
Others :
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4-4dBRAKES [ABS 5.3i TYPE]
6. Diagnostics Chart for On-board Diagnosis System

Condition a) Brakes Deceleration : g
Continuous /Intermittent
b) Accelerator Acceleration : g
Continuous /Intermittent
c) Vehicle speed km/h MPH
Advancing
Accelerating
Reducing speed
Low speed
Turning
Others :
d) Tire inflation pressure Front RH tire : kPa
Front LH tire : kPa
Rear RH tire : kPa
Rear LH tire : kPa
e) Degree of wear Front RH tire :
Front LH tire :
Rear RH tire :
Rear LH tire :
f) Genuine parts are used. :Ye s /No
g) Chain is passed around tires. :Ye s /No
h) T tire is used. :Ye s /No
i) Condition of suspension alignment :
j) Loading state :
k) Repair parts are used. :Ye s /No

What :
l) Others :
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4-4dBRAKES [ABS 5.3i TYPE]
6. Diagnostics Chart for On-board Diagnosis System