SUBARU LEGACY 1996 Service Repair Manual

C: TROUBLE CODE 22, 24, 26 AND 28
—FAULTY ABS SENSOR (FAULTY ABS
SENSOR SIGNAL)—
DIAGNOSIS:

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

Faulty hydraulic unit

Faulty harness/connector

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

ABS does not operate.

TCS does not operate.

TCS operates when should not.
1. Check ABS sensor mechanical trouble.
OK
Not OK
Repair ABS sensor/tone wheel.
2. Check ground circuit of ABS/TCS control
module.
OK
Not OK
Repair harness/connector.
3. Check resistance of ABS sensor.
OK
Not OK
Replace ABS sensor.
4. Check harness connector between ABS/TCS
control module and ABS sensor.
OK
Not OK
Repair harness/connector.
5. Check sources of signal noise.
OK
Not OK
Repair noise sources.
6. Check hydraulic unit operations.
OK
Not OK
Replace hydraulic unit.
Replace ABS/TCS control module.






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8. Diagnostics Chart with Trouble Code

B4M0406
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8. Diagnostics Chart with Trouble Code

G4M0700
G4M0701
1. CHECK ABS SENSOR MECHANICAL TROUBLE.
1) Dismount brake as outlined in manual to gain access to
ABS sensor and tone wheel for inspection.
2) Check pole piece and tone wheel for accumulation of
foreign particles. If necessary, remove foreign particles and
clean.
3) Check tone wheel teeth for cracks for deformities. If
necessary, replace tone wheel (No. of teeth: 44) with a new
one.
4) Check tone wheel for looseness.
Tightening torque:
10—16 N⋅m(1—1.6 kg-m, 7—12 ft-lb)
5) Measure tone wheel-to-pole piece gap over entire
perimeter of the wheel.
SpecificationsFront wheel Rear wheel
0.9—1.4 mm
(0.035—0.055 in)0.7—1.2 mm
(0.028—0.047 in)
If measurements check out“Not OK”, adjust the gap using
spacers (Part No. 26755AA000). If spacers cannot correct
the gap, replace worn sensor or worn tone wheel.
6) Check hub runout.
Specifications 0.05 mm (0.0020 in)
7) The following checks can be made if an oscilloscope is
available.
(1) Raise all four wheels of ground.
(2) Turn ignition switch OFF.
(3) Connect all connectors to ABS control module.
(4) Connect the oscilloscope to the ABS control mod-
ule connector in accordance with trouble code.
(5) Turn ignition switch ON.
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8. Diagnostics Chart with Trouble Code

B4M0721A
(6) Rotate wheels and measure voltage at specified
frequency.
NOTE:
When this inspection is completed, the ABS/TCS control
module sometimes stores the trouble code.
TROUBLE CODE / Connector & terminal:
22 / (P6) No. 8—No.16 (Connect terminal to oscil-
loscope earth head.)
24 / (P7) No. 1—No.11 (Connect terminal to oscil-
loscope earth head.)
26 / (P7) No. 2—No.12 (Connect terminal to oscil-
loscope earth head.)
28 / (P6) No. 7—No.15 (Connect terminal to oscil-
loscope earth head.)
Specified voltage: 0.12—1 V (When it is 20 Hz.)
B4M0405A
2. CHECK GROUND CIRCUIT OF ABS/TCS CONTROL
MODULE.
1) Turn ignition switch OFF.
2) Disconnect connector from ABS/TCS control module.
3) Measure resistance between ABS/TCS control module
connector and body.
Connector & terminal / Specified resistance:
(P4) No. 6—body / 1Ωor less
(P5) No. 5—body / 1Ωor less
(P7) No. 15—body / 1Ωor less
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8. Diagnostics Chart with Trouble Code

B4M0407A
3. CHECK RESISTANCE OF ABS SENSOR.
1) Turn ignition switch OFF.
2) Disconnect connector from ABS sensor.
3) Measure resistance between ABS sensor connector ter-
minals.
TROUBLE CODE / Connector & terminal:
22 / (B6) No. 1—No. 2
24 / (B15) No. 1—No. 2
26 / (P8) No. 1—No. 2
28 / (P9) No. 1—No. 2
Specified resistance: 0.8—1.2 kΩ
4. CHECK HARNESS CONNECTOR BETWEEN ABS/
TCS CONTROL MODULE AND ABS SENSOR.
Check for poor contacts in plug-in connectors. Refer to
“Basic checks”in“FOREWORD”.
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8. Diagnostics Chart with Trouble Code

5. CHECK SOURCES OF SIGNAL NOISE.
1) Check that the mobile phone, personal radio and other
wireless apparatus are correctly installed.
2) Check that the antenna and other possible noise
sources are distant enough from the sensor harness.
3) Check that the sealed wires of the front harness sensor
(in the engine room) are securely grounded.
4) Check that between ABS/TCS control module and the
rear sensor harness has the correct twist pitch.
Twist pitch:
25 mm (0.98 in) or less
6. CHECK HYDRAULIC UNIT OPERATIONS.
1) Operate the ABS sequence control and check that the
brake fluid pressure at the malfunctioning brake line
increases and decreases properly.
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8. Diagnostics Chart with Trouble Code

D: TROUBLE CODE 31, 33, 35, 37, 61 AND 62
—FAULTY INLET SOLENOID VALVE
CIRCUIT(S) AND TCS SOLENOID VALVE
CIRCUIT(S) IN HYDRAULIC UNIT—
DIAGNOSIS:

Faulty harness/connector

Faulty solenoid valve in hydraulic unit

Faulty ABS/TCS control module
TROUBLE SYMPTOM:

ABS does not operate.

TCS does not operate.

ABS sequence control does not operate.

TCS sequence control does not operate.

Air bleeding mode does not operate.
1. Check resistance of solenoid valve.
OK
Not OK
Replace hydraulic unit.
2. Check body short of solenoid valve.
OK
Not OK
Replace hydraulic unit.
3. Check body short of harness.
OK
Not OK
Repair harness.
4. Check harness between ABS/TCS control
module and hydraulic unit.
OK
Not OK
Repair harness/connector.
Replace ABS/TCS control module.




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8. Diagnostics Chart with Trouble Code

B4M0739
B4M0722A
1. CHECK RESISTANCE OF SOLENOID VALVE.
1) Turn ignition switch OFF.
2) Disconnect connector from hydraulic unit.
3) Measure resistance between hydraulic unit terminals.
TROUBLE CODE / Connector & terminal:
31 / (F15) No. 3—No. 9
33 / (F15) No. 4—No. 10
35 / (F15) No. 1—No. 10
37 / (F15) No. 2—No. 9
61 / (F15) No. 12—No. 9
62 / (F15) No. 11—No. 10
Specified resistance: approx. 6±1Ω
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8. Diagnostics Chart with Trouble Code

B4M0723A
2. CHECK BODY SHORT OF SOLENOID VALVE.
1) Turn ignition switch OFF.
2) Disconnect connector from hydraulic unit.
3) Measure resistance between hydraulic unit terminals.
TROUBLE CODE / Connector & terminal:
31 / (F15) No. 3—body
33 / (F15) No. 4—body
35 / (F15) No. 1—body
37 / (F15) No. 2—body
61 / (F15) No. 12—body
62 / (F15) No. 11—body
Specified resistance: 1 MΩor more
B4M0419A
3. CHECK BODY SHORT OF HARNESS.
1) Turn ignition switch OFF.
2) Disconnect connector from hydraulic unit.
3) Disconnect connector from ABS/TCS control module.
4) Measure resistance between ABS/TCS control module
connector terminals.
TROUBLE CODE / Connector & terminal:
31 / (P5) No. 2—body
33 / (P4) No. 2—body
35 / (P4) No. 4—body
37 / (P5) No. 7—body
61 / (P4) No. 5—body
62 / (P5) No. 6—body
Specified resistance: 1 MΩor more
B4M0420A
4. CHECK HARNESS BETWEEN ABS/TCS CONTROL
MODULE AND HYDRAULIC UNIT.
1) Turn ignition switch OFF.
2) Connect connector to hydraulic unit.
3) Disconnect connector from ABS/TCS control module.
4) Measure resistance between ABS/TCS control module
connector terminals.
TROUBLE CODE / Connector & terminal:
31 / (P5) No. 2—(P6) No. 6
33 / (P4) No. 2—(P6) No. 6
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8. Diagnostics Chart with Trouble Code

35 / (P4) No. 4—(P6) No. 6
37 / (P5) No. 7—(P6) No. 6
61 / (P4) No. 5—(P6) No. 6
62 / (P5) No. 6—(P6) No. 6
Specified resistance: 6.2±1.0Ω
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8. Diagnostics Chart with Trouble Code