1997 SUBARU LEGACY ABS

B4M0812
I: 22 FR. SS SOFT
—ABNORMAL FRONT RH ABS SENSOR
(ABNORMAL ABS SENSOR SIGNAL)—
B4M0949
J: 24 FL. SS SOFT
—ABNORMAL FRONT LH ABS SENSOR
(ABNORMAL ABS SENSOR SIGNAL)—
B4M0950
K: 26 RR. SS SOFT
—ABNORMAL REAR RH ABS SENSOR
(ABNORMAL ABS SENSOR SIGNAL)—
B4M0951
L: 28 RL. SS SOFT
—ABNORMAL REAR LH ABS SENSOR
(ABNORMAL ABS SENSOR SIGNAL)—
141
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

DIAGNOSIS:

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

Faulty harness/connector
TROUBLE SYMPTOM:

ABS does not operate.
10L1.Check output of ABS sensor using select
monitor.

10L2.Check poor contact in connector between
ABSCM and ABS sensor.
10L3.Check sources of signal noise.
10L4.Check shield circuit.
10L5.Check ABSCM.
10L6.Check ABS sensor mechanical trouble.
10L7.Check resistance of ABS sensor.
10L8.Check ground short of ABS sensor.
10L9.Check harness connector between ABSCM
and ABS sensor.
10L10.Check ground short of harness.
10L11.Check ground circuit of ABSCM.
10L12.Check poor contact in connector between
ABSCM and ABS sensor.
10L13.Check sources of signal noise.
10L14.Check shield circuit.
10L15.Check ABSCM.













142
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

WIRING DIAGRAM:
B4M1035
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4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

B4M0922
10L1CHECK OUTPUT OF ABS SENSOR
USING SELECT MONITOR.
Read the ABS sensor output corresponding to the faulty
system in the select monitor function mode.
NOTE:
The select monitor display shows that the front right wheel
is rotating at 30 km/h.
: Does the speed indicated on the display
change in response to the speedometer
reading during acceleration/deceleration
when the steering wheel is in the straight-
ahead position?
: Go to step10L2.
: Go to step10L3.
10L2CHECK POOR CONTACT IN CONNEC-
TOR BETWEEN ABSCM AND ABS SEN-
SOR.
: Is there poor contact in connectors between
ABSCM and ABS sensor?
: Repair connector.
: Go to step10L3.
10L3
CHECK SOURCES OF SIGNAL NOISE.
: Is the car telephone or the wireless trans-
mitter properly installed?
: Go to next.
: Properly install the car telephone or the wireless
transmitter.
: Are noise sources (such as an antenna)
installed near the sensor harness?
: Install the noise sources apart from the sensor
harness.
: Go to step10L4.
144
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

B4M1038A
10L4
CHECK SHIELD CIRCUIT.
1) Connect all connectors.
2) Measure resistance between shield connector and
chassis ground.
: Trouble code/Connector & terminal
22/(B100) No. 11—Chassis ground
24/(B100) No. 2—Chassis ground
26/(P1) No. 8—Chassis ground
28/(P1) No. 3—Chassis ground
Is resistance less than 0.5Ω?
: Go to step10L5.
: Repair shield harness.
10L5
CHECK ABSCM.
1) Connect all connectors.
2) Erase the memory.
3) Perform inspection mode.
4) Read out the trouble code.
: Is the same trouble code as in the current
diagnosis still being output?
: Replace ABSCM.
: Go to next.
: Are other trouble codes being output?
: Proceed with the diagnosis corresponding to the
trouble code.
: A temporary noise interference.
145
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

10L6CHECK ABS SENSOR MECHANICAL
TROUBLE.
: Tightening torque:
32±10 N⋅m (3.3±1.0 kg-m, 24±7 ft-lb)
Are the ABS sensor installation bolts tight-
ened securely?
: Go to next.
: Tighten ABS sensor installation bolts securely.
: Tightening torque:
13±3 N⋅m (1.3±0.3 kg-m, 9±2.2 ft-lb)
Are the tone wheel installation bolts tight-
ened securely?
: Go to next step.
: Tighten tone wheel installation bolts securely.
G4M0700
1) Measure tone wheel to pole piece gap over entire
perimeter of the wheel.
: Is the gap within the specifications shown
in the following table?
SpecificationsFront wheel Rear wheel
0.9—1.4 mm
(0.035—0.055 in)0.7—1.2 mm
(0.028—0.047 in)
G4M0701
: Go to next.
: Adjust the gap.
NOTE:
Adjust the gap using spacer (Part No. 26755AA000). If
spacers cannot correct the gap, replace worn sensor or
worn tone wheel.
: Is an oscilloscope available?
: Go to next step.
: Go to step 10).
2) Raise all four wheels of ground.
3) Turn ignition switch OFF.
4) Disconnect connector from ABS control module.
5) Disconnect connector cover from connector.

6) Connect connector to ABS control module.
7) Connect the oscilloscope to the ABS control module
connector in accordance with trouble code.
8) Turn ignition switch ON.
146
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

B4M0816A
9) Rotate wheels and measure voltage at specified fre-
quency.
NOTE:
When this inspection is completed, the ABS control mod-
ule sometimes stores the trouble code 29.
TROUBLE CODE / Connector & terminal:
22 / (F49) No. 14 (+)—No. 15 ()
24 / (F49) No. 49 (+)—No. 19 ()
26 / (F49) No. 18 (+)—No. 46 ()
28 / (F49) No. 16 (+)—No. 17 ()
Specified voltage: 0.12—1 V (When it is 20 Hz.)
: Is oscilloscope pattern smooth, as shown in
figure?
: Go to step10L7.
: Go to next step.
10) Remove disc rotor from hub in accordance with trouble
code.
: Is the ABS sensor pole piece or the tone
wheel contaminated by dirt or other foreign
matter?
: Thoroughly remove dirt or other foreign matter.
: Go to next.
: Are there broken or damaged teeth in the
ABS sensor pole piece or the tone wheel?
: Replace ABS sensor or tone wheel.
: Go to next step.
11) Measure hub runout.
: Is the runout less than 0.05 mm (0.0020 in)?
: Go to step10L7.
: Repair hub.
B4M0806B
B4M1036A
10L7
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/to (B6) No. 1—No. 2
24/to (B15) No. 1—No. 2
26/to (P8) No. 1—No. 2
28/to (P9) No. 1—No. 2
Is resistance 0.8—1.2 kΩ?
: Go to step10L8.
: Replace ABS sensor.
147
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

B4M0818B
B4M1042A
10L8CHECK GROUND SHORT OF ABS SEN-
SOR.
Measure resistance between ABS sensor and chassis
ground.
: Trouble code/Connector & terminal
22/to (B6) No. 1—Chassis ground
24/to (B15) No. 1—Chassis ground
26/to (P8) No. 1—Chassis ground
28/to (P9) No. 1—Chassis ground
Is resistance more than 1 MΩ?
: Go to step10L9.
: Replace ABS sensor.
B4M0809A
10L9CHECK HARNESS CONNECTOR
BETWEEN ABSCM AND ABS SENSOR.
1) Connect connector to ABS sensor.
2) Disconnect connector from ABSCM.
3) Measure resistance at ABSCM connector terminals.
: Trouble code/Connector & terminal
22/(F49) No. 14—No. 15
24/(F49) No. 49—No. 69
26/(F49) No. 18—No. 46
28/(F49) No. 16—No. 17
Is resistance 0.8—1.2 kΩ?
: Go to step10L10.
: Repair harness connector between ABSCM and
ABS sensor.
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4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor