SUBARU LEGACY 1997 Service Repair Manual

B4M0374AB4M0376AB4M0646A
B4M0377AB4M0379AB4M0378A
B4M0375AB4M0645A
5
4-4bBRAKES
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
6
4-4bBRAKES
4. Schematic

5. Control Module I/O Signal
1. I/O SIGNAL VOLTAGE
Contents Connector No. Terminal No.Input/Output signals
Measured value and measuring conditions
ABS
sensor
(Wheel
speed
sensor)Front left wheel P7 1—11 0.12—1 V (When it is 10 Hz.)
Front right wheel P6 8—16 0.12—1 V (When it is 10 Hz.)
Rear left wheel P6 7—15 0.12—1 V (When it is 10 Hz.)
Rear right wheel P7 2—12 0.12—1 V (When it is 10 Hz.)
Hydraulic
unitSolenoid
valveFront left outlet P4 1—GND
10—14 V when the valve is OFF.
Less than 1.5 V when the valve is ON. Front right outlet P5 3—GND
Rear left outlet P5 8—GND
Rear right outlet P4 3—GND
Front left inlet P4 2—GND
10—14 V when the valve is OFF.
Less than 1.0 V when the valve is ON. Front right inlet P5 2—GND
Rear left inlet P5 7—GND
Rear right inlet P4 4—GND
TCS 1 P4 5—GND
10—14 V when the valve is OFF.
Less than 1.0 V when the valve is ON.
TCS 2 P5 6—GND
Valve power supply P6 6—GND Ignition switch ON, 10—14 V
Valve relay power supply P6 1—GNDLess than 1.2 V when IGN is ON.
10—14 V when the system is down.
Motor relay power supply P6 9—GNDLess than 1.0 V when the motor is ON.
10—14 V when the motor is OFF.
Motor sensor signalsP7 3—GNDCyclic waveform of more than 180 Hz
when the motor across terminals is ON.
Less than 70 Hz when the motor is OFF. P7 13—GND
Pressure switch P7 6—GNDH/L toggle signal with the brake pedal off
(Cycle 14 mS, H: 10—14 V, L: less than
0.7 V). 10—14 V with the brake pedal
depressed.
Pedal
stroke
sensorOutput signals P7 5—GND 0.7—0.9 V with the brake pedal off.
Power supply P7 4—14 5±0.4 V
Stop light
switchSwitch P7 7—GNDLess than 2 V when the stop light is off.
10—12 V when the stop light is on.
Switch test signal P7 18—GNDH/L toggle signal with the brake pedal off
(Cycle 14 mS, H: 10—12 V, L: less than
0.7 V). Less than 2 V with the brake pedal
depressed.
TCS OFF switch P7 16—GNDLess than 2.0 V with the switch pressed
and 10—12 V with it released.
Indicator
lightTCS OFF P6 10—GND
Less than2Vwhenthelight is on and
10—12 V when it is off. TCS operation P6 11—GND
TCS warning P6 3—GND
ABS warning P6 2—GND
7
4-4bBRAKES
5. Control Module I/O Signal

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
8
4-4bBRAKES
5. Control Module I/O Signal

2. I/O SIGNAL DIAGRAM
B4H0336
9
4-4bBRAKES
5. Control Module I/O Signal

3. LIST OF ABS/TCS ON-BOARD DIAGNOSTICS
FUNCTIONS
Trouble codeDiagnostic items
<detailed diagnostic items>Detection timingIndicator
light ON
Parts concerned
At initial checking
Under no control
Under ABS control
Under TCS control
In diagnostic mode
ABS warning light
TCS warning light
TCS OFF indicator light
21 FR
23 FL
25 RR
27 RLDetection of fault in ABS sensor hardware
<open/short circuits of sensor>
 —ABS sensor (ABS/TCS C/M)
22 FR
24 FL
26 RR
28 RLDetection of fault in ABS sensor software
<variations in wheel speed> —ABS sensor (ABS/TCS C/M)
 —ABS sensor harness circuit (ABS/TCS C/M)
Detection of fault in ABS sensor software
<decompression mode>—ABS sensor and solenoid valve (ABS/TCS C/M)
—ABS sensor (ABS/TCS C/M)
Detection of fault in sensor software
<speed higher than prescribed> —ABS sensor (ABS/TCS C/M)
31 FRI
32 FRO
33 FLI
34 FLO
35 RRI
36 RRO
37 RLI
38 RLO
61 TCS1
62 TCS2Abnormal valve
<Abnormal valve>
*
—Solenoid valve (ABS/TCS C/M)
41 Abnormal ABS/TCS C/M
<Abnormal ABS/TCS C/M> —ABS/TCS C/M
42 Abnormal line voltage
<Abnormal line voltage>—Power source operating environment (ABS/TCS C/M)
—Power source voltage drop
<Power source voltage drop> —
—
*: Except when trouble code is being displayed.
10
4-4bBRAKES
5. Control Module I/O Signal

Trouble codeDiagnostic items
<detailed diagnostic items>Detection timingIndicator
light ON
Parts concerned
At initial checking
Under no control
Under ABS control
Under TCS control
In diagnostic mode
ABS warning light
TCS warning light
TCS OFF indicator light
43 Abnormal EGI communication line
<Abnormal EGI communication line>——AET communication line (ABS/TCS C/M)
——
——
——AEB communication line (ABS/TCS C/M)
——
——
——AEC communication line (ABS/TCS C/M)
——
——
—Abnormal EGI communication line
<Abnormal EGI communication line>——EAM communication line (ABS/TCS C/M)
51 Abnormal valve relay
<failure of valve relay ON>
<failure of valve relay OFF>—Valve relay (ABS/TCS C/M)
Abnormal valve relay
<failure of valve relay OFF> —Valve relay (ABS/TCS C/M)
 —
52 Abnormal motor system
<failure of motor relay OFF> —Motor (ABS/TCS C/M)
Abnormal motor system
<failure of motor relay ON> —Motor (ABS/TCS C/M)
Abnormal motor system
<failure of motor relay OFF>—
11
4-4bBRAKES
5. Control Module I/O Signal

Trouble codeDiagnostic items
<detailed diagnostic items>Detection timingIndicator
light ON
Parts concerned
At initial checking
Under no control
Under ABS control
Under TCS control
In diagnostic mode
ABS warning light
TCS warning light
TCS OFF indicator light
54 Abnormal pedal stroke sensor and stop light switch
<open/short circuits of stroke sensor> —Pedal stroke sensor (ABS/TCS C/M)
Abnormal pedal stroke sensor and stop light switch
<comparison of acceleration and stroke sensor>—Pedal stroke sensor (ABS/TCS C/M)
Abnormal pedal stroke sensor and stop light switch
<comparison of stroke sensor and brake lamp switch>—Stop light switch, pedal stroke sensor (ABS/TCS C/M)
Abnormal pedal stroke sensor and stop light switch
<comparison of stroke sensor and pump exitation>—Pump, pedal stroke sensor (ABS/TCS C/M)
Abnormal stroke sensor and stop light switch
<open circuit of stop light switch>——Stop light switch circuit (ABS/TCS C/M)
57 Abnormal fluid level sensor
<Abnormal fluid level sensor>—Fluid level sensor circuit
—Abnormal fluid level sensor
<Abnormal fluid level sensor>
<Insufficient brake fluid> —Fluid level sensor circuit, reservoir
58 Abnormal pressure switch
<Abnormal pressure switch>——Pressure switch (ABS/TCS C/M)
——Pressure switch, stop light switch (ABS/TCS C/M)
——Pressure switch (ABS/TCS C/M)
12
4-4bBRAKES
5. Control Module I/O Signal

6. Diagnostics Chart for On-board
Diagnosis System
A: BASIC DIAGNOSTICS PROCEDURE
TROUBLE OCCURS.
Ask the customer when and how the
trouble occurred using interview
check list. <Ref. to 4-4b [T6B0].>
PRE-INSPECTION
<Ref. to 4-4b [T200].>
INSPECTION MODE
<Ref. to 4-4b [T6C0].>
CALLING UP A TROUBLE CODE.
<Ref. to 4-4b [T6D1].>No trouble code is readable.

Inspection using Diagnostic Chart for
Warning Light Failure.
<Ref. to 4-4b [T700].>
Record all trouble codes.
Trouble codes
are issued.
Only the start code is issued.
Inspection using General Diagnostics
Chart
<Ref. to 4-4b [T1100].>
Perform diagnostics in accordance with trouble code.
<Ref. to 4-4b [T8A0].>
Trouble code
designated.

Repair.
Clear memory.
<Ref. to 4-4b [T6D2].>
INSPECTION MODE
<Ref. to 4-4b [T6C0].>
CALLING UP A TROUBLE CODE.
<Ref. to 4-4b [T6D1].>
Only the start code is issued.
CONFIRMATION TEST
END
NOTE:

To check harness for broken wires or short circuits,
shake it while holding it or the connector.

When TCS warning light illuminates, read and record
trouble code indicated by TCS warning light.












13
4-4bBRAKES
6. Diagnostics Chart for On-board Diagnosis System

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)
14
4-4bBRAKES
6. Diagnostics Chart for On-board Diagnosis System