sensor SUBARU LEGACY 1995 Service Repair Manual

B4M0527
2. B.SW SOFT (G)
—Irregular value in comparison stroke sensor and
vehicle acceleration comparison—
DIAGNOSIS:

Faulty stroke sensor

Faulty harness/connector

Faulty stop light switch

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

ABS and TCS do not operate.
NOTE:
Operate the function F09 in select monitor TCS mode, and
read the sensor output step.
If system is normal, the output reading is 1 when brake
pedal is not depressed, and it changes from 2 to 3, 4 and
5 in accordance with the brake pedal depressing. If so, skip
check steps 2 through 4.
1. Check correct installation of stroke sensor.

OK
Not OK
Repair stroke sensor.
2. Check resistance of stroke sensor.

OK
Not OK
Replace stroke sensor.
3. Check stroke sensor operation.

OK
Not OK
Replace stroke sensor.
4. Check harness between stroke sensor and
ABS/TCS control module.

OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.




120
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

B4M0528
3. B.SW SOFT (B)
—Irregular value in stroke sensor and brake light
switch comparison—
DIAGNOSIS:

Faulty stroke sensor

Faulty stop light switch

Faulty harness/connector

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

ABS and TCS do not operate.
NOTE:
Operate the function F09 in select monitor TCS mode, and
read the sensor output step.
If system is normal, the output reading is 1 when brake
pedal is not depressed, and it changes from 2 to 3, 4 and
5 in accordance with the brake pedal depressing. If so, skip
check steps 1 and 2 through 7.
Then, operate the function FA0 and check the stop and
brake switches by B1 LED ON/OFF. If system is normal,
LED comes on when depressing brake pedal, and goes off
when not depressing. If so, skip check steps 3 through 6.
1. Check resistance of stroke sensor.

OK
Not OK
Replace stroke sensor.
2. Check stroke sensor operation.

OK
Not OK
Replace stroke sensor.
3. Check contact point of stop light switch.

OK
Not OK
Replace stroke sensor.
4. Check body short of stop light switch.

OK
Not OK
Replace stroke sensor.
5. Check power supply of stop light switch.

OK
Not OK
Repair harness/connector.
6. Check input voltage of ABS/TCS control mod-
ule.

OK
Not OK
Repair harness/connector.
7. Check harness between stroke sensor and
ABS/TCS control module.

OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.







121
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

B4M0529
4. B.SW SOFT (P)
—Comparison between stroke sensor and pump
output—
DIAGNOSIS:

Faulty stroke sensor

Faulty harness/connector

Faulty pump unit in hydraulic unit

Faulty stop light switch

Faulty ABS/TCS control module
NOTE:
Operate the function F09 in select monitor TCS mode, and
read the sensor output step.
If system is normal, the output reading is 1 when brake
pedal is not depressed, and it changes from 2 to 3, 4 and
5 in accordance with the brake pedal depressing. If so, skip
check steps 2 through 4.
1. Check correct installation of stroke sensor.

OK
Not OK
Repair stroke sensor.
2. Check resistance of stroke sensor.

OK
Not OK
Replace stroke sensor.
3. Check stroke sensor operation.

OK
Not OK
Replace stroke sensor.
4. Check harness between stroke sensor and
ABS/TCS control module.

OK
Not OK
Repair harness/connector.
5. Check pump unit operation.

OK
Not OK
Replace hydraulic unit.
Replace ABS/TCS control module.





122
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

B4M0530
5. B.SW SOFT (O)
—Broken brake light switch—
DIAGNOSIS:

Faulty stop light switch

Faulty harness/connector

Faulty stroke sensor

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

TCS does not operate.
NOTE:
Operate the function FA0 in select monitor TCS mode, and
check the stop and brake switches by B1 LED ON/OFF. If
system is normal, LED comes on when depressing brake
pedal, and goes off when not depressing. If so, skip check
steps 2 through 4.
1. Check correct installation of stroke sensor.

OK
Not OK
Repair stroke sensor.
2. Check contact point of stop light switch.

OK
Not OK
Replace stroke sensor.
3. Check input voltage of ABS/TCS control mod-
ule.

OK
Not OK
Repair harness/connector.
4. Check stop light circuit.

OK
Not OK
Repair harness/connector.
Replace stop light bulb and/or fuse.
Replace ABS/TCS control module.




123
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

B4M0531
Z: TROUBLE CODE 57
FLUID LEVEL SS
—Irregular signal from fluid level sensor—
DIAGNOSIS:

Faulty fluid level sensor circuit

Faulty harness/connector

Faulty ABS/TCS control module

Faulty generator
TROUBLE SYMPTOM:

ABS and TCS do not operate.
1. Check generator function.

OK
Not OK
Repair generator.
2. Check input voltage of ABS/TCS control mod-
ule.

OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.


124
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

B4M0532
AA: TROUBLE CODE 58
PRESSURE SW
—Faulty pressure switch—
DIAGNOSIS:

Faulty pressure

Faulty stop light switch

Faulty ABS/TCS control module

Faulty harness/connector
TROUBLE SYMPTOM:

TCS does not operate.
NOTE:
Check using the select monitor.
Operate the function FA0 in select monitor TCS mode. The
stop and brake switches can be checked by B1 LED
ON/OFF. If system is normal, LED comes on when
depressing brake pedal, and goes off when not depressing.
If so, skip check steps 5 through 8.
1. Check contact point of pressure switch.

OK
Not OK
Replace hydraulic unit.
2. Check body short of pressure switch.

OK
Not OK
Replace hydraulic unit.
3. Check harness between pressure switch and
ABS/TCS control module.

OK
Not OK
Repair harness/connector.
4. Check body short of pressure switch harness.

OK
Not OK
Repair harness.
5. Check contact point of stop light switch.

OK
Not OK
Replace stroke sensor.
6. Check body short of stop light switch.

OK
Not OK
Replace stroke sensor.
7. Check power supply of stop light switch.

OK
Not OK
Repair harness.
8. Check input voltage of ABS/TCS control mod-
ule.

OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.








125
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

11. General Diagnostics Table
: Primary expected causes: Secondary expected causes
Trouble conditions
SymptomsHydraulic
unit
Speed sensor
P valve
Master cylinder
Calipers and piston
Pad
Rotor
Hand brake
Piping
Mixture of air
Brake booster and check valve
Axle and wheel
Alignment
Play of pedal
Rough road surface
Semicylindrical road surface
Loose or worn suspension
Tire
Wrong connection and wiring
Stroke sensor Solenoid valve
Motor
Mount bush ABS function
Directional stability cannot be
obtained when braking.Vehicle turns to right or left. 
Vehicle spins.
Out-of-order brakesLong braking distance
 
Brakes lock.  
Brakes drag.
Long pedal stroke  
Abnormal vehicle pitching 
Unstable braking force. One-
side brake refuses to work. 
TCS function
When accelerating abruptly,
directional stability cannot be
obtained when traveling on a
slippery road surface.Vehicle moves unsteadily.
Handle refuses to work.
Handle loses control. 
Bad acceleration, engine stall-
ing (In addition to the causes
listed here, check the ECM
specifications.)Engine stalls. Engine speed
fails to increase.
Engine speed increases sud-
denly.
Vibration occurs and abnormal
noise is produced.

When applying brakes abruptly.

When accelerating abruptly.

When driving on a slippery
road surface.Brake pedal heavily vibrates
when applying brakes.
   
Loud hydraulic unit operating
noise
Noise is produced from front
of vehicle.
Noise is produced from rear of
vehicle.
NOTE:
This list includes no engine failure and transmission failure.
127
4-4bBRAKES
11. General Diagnostics Table

6. INSPECTOR
Before advancing the vehicle after the engine starts, drive
the pump motor and valve for a very short time to function-
ally check the ABS/TCS brakes. It is not abnormal if, at this
time, operating noises of the valve and motor are produced
or kickback of the brake pedal is felt when stepping on the
pedal.
7. WHEN ATTACHING CHAINS
It is sometimes a good idea to turn off the TCS for better
advancing and accelerating the vehicle.
8. WHEN A DRUM TESTER IS USED (SPEEDOMETER
TEST, EXHAUST GAS TEST, BRAKE TEST, ETC.)
Before performing tests, turn the TCS off by operating the
TCS OFF switch or disconnect the fuse of ECM input
power source to put the machine out of operation. If oper-
ating other parts to put the TCS in the fail state
intentionally, trouble code will be recorded. Make sure to
clear the memory. Also, in a 2-wheel tester, wheel speed
sensor failure can be detected, making the TCS fail. This
case is also not abnormal and clearing the memory is
required.
129
4-4bBRAKES
12. Phenomena Peculiar to the System

D: LIST OF TROUBLE CODES
1. TROUBLE CODES
Trouble code/Contents of troubles Memory function Contents of diagnosis Page
02 Provided.1) Front sensor harness is shorted.
2) Airbag main harness is shorted.
3) Airbag module harness (Dr/Ps) is shorted.
4) Roll connector is shorted.
5) Airbag control module is faulty.16
03 Provided.1) Front sensor harness circuit is open.
2) Front sensor unit circuit is open.18
04 Provided.1) Airbag main harness circuit is shorted.
2) Airbag module harness (Ps) circuit is shorted.
3) Airbag control module is faulty.19
11 Provided.1) Airbag control module is faulty.
2) Airbag main harness circuit is open.
3) Fuse No. 8 is blown.
4) Body harness circuit is open.20
12 Provided.1) Airbag main harness circuit is open.
2) Airbag module harness (Dr) circuit is open.
3) Roll connector circuit is open.
4) Airbag control module is faulty.22
13 Provided.1) Airbag main harness circuit is shorted.
2) Airbag module harness (Dr) is shorted.
3) Roll connector circuit is shorted.
4) Airbag control module is faulty.23
14 Not provided.1) (AB9) and (AB10) are not connected properly.
2) (AB2) and (AB7) are not connected properly.
3) (AB3) and (AB8) are not connected properly.
4) (AB4), (AB5) and (AB6) are not connected
properly to airbag control module.24
21 Provided. Airbag control module is faulty. 26
22 Provided.1) Airbag main harness circuit is open.
2) Airbag module harness (Ps) circuit is open.
3) Airbag control module is faulty.27
23 Provided.1) Airbag main harness is shorted to power supply.
2) Front sensor harness is shorted to power supply.
3) Airbag module harness (Dr/Ps) is damaged.
4) Roll connector is shorted to power supply.
5) Airbag control module is faulty.28
24 Provided.1) Airbag main harness circuit is open.
2) Airbag module harness (Dr) circuit is open.
3) Roll connector circuit is open.
4) Airbag control module is faulty.
5) Above diagnosis plus other faulty of airbag
modular parts.30
31 Not provided.1) Airbag control module is faulty.
2) Airbag main harness circuit is open.
3) Fuse No. 16 is blown.
4) Body harness circuit is open.32
32 Provided.1) Airbag main harness circuit is open.
2) Airbag module harness (Ps) circuit is open.
3) Airbag control module is faulty.
4) Above diagnosis plus other faulty of airbag
modular parts.34
NOTE: Dr: Driver side Ps: Passenger side
10
5-5SUPPLEMENTAL RESTRAINT SYSTEM
4. Diagnostics Chart for On-board Diagnostic System

5. Diagnostics Chart with Trouble Code

A: TROUBLE CODE 02
DIAGNOSIS:
Front sensor harness is shorted.
Airbag main harness is shorted.
Airbag module harness (Driver or passenger) is
shorted.
Roll connector is shorted.
Airbag control module is faulty.
1. Front sensor and harness inspection
O.K.
Not O.K.
Replace front sensor.
2. Airbag main harness inspection
O.K.
Not O.K.
Replace airbag main harness.
Replace airbag control module.
CAUTION:
Before performing diagnostics on airbag system, turn
ignition switch“OFF”, disconnect battery ground ter-
minal and then wait at least 20 seconds.
After 20 seconds elapse, remove instrument panel
lower cover, and disconnect (AB3) and (AB8), (AB9)
and (AB10).


15
5-5SUPPLEMENTAL RESTRAINT SYSTEM
5. Diagnostics Chart with Trouble Code