1997 SUBARU LEGACY brake sensor

B4M0508
K: TROUBLE CODE 28
1. RL.SS W.SPEED
—Irregular signals from rear left ABS sensor—
DIAGNOSIS:

Faulty ABS sensor signal (noise, irregular signal, etc.)

Faulty harness/connector

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

ABS and TCS do not operate.
NOTE:
The procedures used are the same as those for FR.SS
W.SPEED.

B4M0509
2. RL.SS OR MV
—Irregular signals from rear left ABS sensor in
decompressing mode—
DIAGNOSIS:

Faulty ABS sensor signal (noise, irregular signal, etc.)

Faulty hydraulic unit

Faulty harness/connector

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

ABS and TCS do not operate.
NOTE:
The procedures used are the same as those for FR.SS OR
MV.

B4M0510
3. RL.SS OVER
—Excessive speed of rear left ABS sensor signal—
DIAGNOSIS:

Faulty ABS sensor signal (noise, irregular signal, etc.)

Faulty harness/connector

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

ABS and TCS do not operate.
NOTE:
The procedures used are the same as those for FR.SS
OVER.

106
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

B4M0524
X: TROUBLE CODE 52
1. MOTOR ON
—Motor relay ON malfunction—
DIAGNOSIS:

Faulty motor relay

Faulty motor

Faulty motor sensor

Faulty harness

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

ABS does not operate.

TCS does not operate.
1. Check body short of harness.

OK
Not OK
Repair harness.
2. Check motor operation.

OK
Not OK
Replace motor relay.
3. Check body short of motor sensor.

OK
Not OK
Replace hydraulic unit.
4. Check body short of motor sensor harness.

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




11 6
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

B4M0525
2. MOTOR OFF
—Motor relay OFF malfunction—
DIAGNOSIS:

Faulty motor relay

Faulty motor

Faulty motor sensor

Faulty harness/connector

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

ABS and TCS do not operate.
1. Check resistance of motor relay.

OK
Not OK
Replace motor relay.
2. Check input voltage of motor relay.

OK
Not OK
Repair harness/connector.
3. Check harness between ABS/TCS control
module and motor relay.

OK
Not OK
Repair harness/connector.
4. Check motor operation.

OK
Not OK
Go to step 9.
5. Check resistance of motor sensor.

OK
Not OK
Replace hydraulic unit.
6. Check body short of motor sensor.

OK
Not OK
Replace hydraulic unit.
7. Check harness between ABS/TCS control
module and motor sensor.

OK
Not OK
Repair harness/connector.
8. Check body short of motor sensor harness.

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








11 7
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

9. Check contact point of motor relay.

OK
Not OK
Replace motor relay.
10. Check harness between motor and motor
relay.

OK
Not OK
Repair harness/connector.
11. Check body short of motor harness.

OK
Not OK
Repair harness.
12. Check ground circuit of motor.

OK
Not OK
Repair harness/connector.
Replace hydraulic unit.
NOTE:
The check can also be made by analyzing the sensor out-
put signal with oscilloscope during the TCS sequence con-
trol operation. If the ECM female connector end gives cor-
rect value, skip steps 5 through 8.
If not, operate the TCS sequence control again and mea-
sure the value at motor sensor male connector end, with
the motor sensor connector disconnected. If the value is
OK, proceed with steps 7 through 8 above.




11 8
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

B4M0526
Y: TROUBLE CODE 54
1. B.SW HARD
—Break and short circuit at stroke sensor or its
wiring—
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 1 through 5.
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 body short of stroke sensor.

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 body short of stroke sensor harness.

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





11 9
4-4bBRAKES
10. Diagnostic Chart with Select Monitor

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