1997 SUBARU LEGACY ABS

DIAGNOSIS:

Faulty ABS sensor (Broken wire, input voltage too high)

Faulty harness connector
TROUBLE SYMPTOM:

ABS does not operate.
10H1.Check output of ABS sensor using select
monitor.

10H2.Check ABS sensor mechanical trouble.
10H3.Check poor contact in connector between
ABSCM and ABS sensor.
10H4.Check ABSCM.
10H5.Check resistance of ABS sensor.
10H6.Check battery short of ABS sensor.
10H7.Check harness connector between ABSCM
and ABS sensor.
10H8.Check battery short of harness.
10H9.Check ABS sensor mechanical trouble.
10H10.Check poor contact in connector between
ABSCM and ABS sensor.
10H11.Check ABSCM.









133
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

WIRING DIAGRAM:
B4M1035
134
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

B4M0922
10H1CHECK 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 step10H2.
: Go to step10H5.
10H2CHECK 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)
135
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

G4M0701
: Go to next step.
: Adjust the gap.
NOTE:
Adjust the gap using spacers (Part No. 26755AA000). If
spacers cannot correct the gap, replace worn sensor or
worn tone wheel.
2) Measure hub runout.
: Is the runout less than 0.05 mm (0.0020 in)?
: Go to step10H3.
: Repair hub.
10H3CHECK 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 step10H4.
10H4
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 poor contact.
NOTE:
Check harness and connectors between ABSCM and ABS
sensor.
136
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

B4M0806B
B4M1036A
10H5
CHECK RESISTANCE OF ABS SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ABS sensor.
3) Measure resistance of ABS sensor connector terminals.
: Trouble code/Connector & terminal
21/to (B6) No. 1—No. 2
23/to (B15) No. 1—No. 2
25/to (P8) No. 1—No. 2
27/to (P9) No. 1—No. 2
Is resistance 0.8—1.2 kΩ?
: Go to step10H6.
: Replace ABS sensor.
B4M0807B
B4M1037A
10H6CHECK BATTERY SHORT OF ABS SEN-
SOR.
1) Disconnect connector from ABSCM.
2) Turn ignition switch to ON.
3) Measure voltage between ABS sensor and chassis
ground.
: Trouble code/Connector & terminal
21/to (B6) No. 1 (+)—Chassis ground ()
23/to (B15) No. 1 (+)—Chassis ground ()
25/to (P8) No. 1 (+)—Chassis ground ()
27/to (P9) No. 1 (+)—Chassis ground ()
Is voltage 0 V?
: Go to next step.
: Replace ABS sensor.
4) Turn ignition switch to OFF.
5) Measure voltage between ABS sensor and chassis
ground.
: Trouble code/Connector & terminal
21/to (B6) No. 1 (+)—Chassis ground ()
23/to (B15) No. 1 (+)—Chassis ground ()
25/to (P8) No. 1 (+)—Chassis ground ()
27/to (P9) No. 1 (+)—Chassis ground ()
Is voltage 0 V?
: Go to step10H7.
: Replace ABS sensor.
137
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

B4M0809A
10H7CHECK HARNESS CONNECTOR
BETWEEN ABSCM AND ABS SENSOR.
1) Connect connector to ABS sensor.
2) Measure resistance between ABSCM connector termi-
nals.
: Trouble code/Connector & terminal
21/(F49) No. 14—No. 15
23/(F49) No. 49—No. 19
25/(F49) No. 18—No. 46
27/(F49) No. 16—No. 17
Is resistance 0.8—1.2 kΩ?
: Go to step10H8.
: Repair harness connector between ABSCM and
ABS sensor.
B4M0810A
10H8
CHECK BATTERY SHORT OF HARNESS.
1) Turn ignition switch to ON.
2) Measure voltage between ABSCM connector and chas-
sis ground.
: Trouble code/Connector & terminal
21/(F49) No. 14—Chassis ground
23/(F49) No. 49—Chassis ground
25/(F49) No. 18—Chassis ground
27/(F49) No. 16—Chassis ground
Is voltage 0 V?
: Go to next step.
: Repair harness between ABSCM and ABS sen-
sor.
3) Turn ignition switch to OFF.
4) Measure voltage between ABSCM connector and chas-
sis ground.
: Trouble code/Connector & terminal
21/(F49) No. 14—Chassis ground
23/(F49) No. 49—Chassis ground
25/(F49) No. 18—Chassis ground
27/(F49) No. 16—Chassis ground
Is voltage 0 V?
: Go to step10H9.
: Repair harness between ABSCM and ABS sen-
sor.
138
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

10H9CHECK 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 step.
: Adjust the gap.
NOTE:
Adjust the gap using spacers (Part No. 26755AA000). If
spacers cannot correct the gap, replace worn sensor or
worn tone wheel.
2) Measure hub runout.
: Is the runout less than 0.05 mm (0.0020 in)?
: Go to step10H10.
: Repair hub.
139
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor

10H10CHECK 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 step10H11.
10H11
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 poor contact.
NOTE:
Check harness and connectors between ABSCM and ABS
sensor.
140
4-4cBRAKES [ABS 5.3 TYPE]
10. Diagnostics Chart with Select Monitor