SUBARU LEGACY 1997 Service Repair Manual

B4M0881A
8K23
CHECK BATTERY SHORT OF HARNESS.
1) Disconnect connector from hydraulic unit.
2) Turn ignition switch to ON.
3) Measure voltage between ABSCM connector and chas-
sis ground.
: Connector & terminal
(F49) No. 30 (+)—Chassis ground ()
(F49) No. 24 (+)—Chassis ground ()
(F49) No. 23 (+)—Chassis ground ()
(F49) No. 31 (+)—Chassis ground ()
(F49) No. 3 (+)—Chassis ground ()
(F49) No. 51 (+)—Chassis ground ()
(F49) No. 50 (+)—Chassis ground ()
(F49) No. 4 (+)—Chassis ground ()
Is voltage 0 V?
: Go to next step.
: Repair harness between hydraulic unit and
ABSCM and check all fuses.
4) Turn ignition switch to OFF.
5) Measure voltage between ABSCM connector and chas-
sis ground.
: Connector & terminal
(F49) No. 30 (+)—Chassis ground ()
(F49) No. 24 (+)—Chassis ground ()
(F49) No. 23 (+)—Chassis ground ()
(F49) No. 31 (+)—Chassis ground ()
(F49) No. 3 (+)—Chassis ground ()
(F49) No. 51 (+)—Chassis ground ()
(F49) No. 50 (+)—Chassis ground ()
(F49) No. 4 (+)—Chassis ground ()
Is voltage 0 V?
: Go to step8K24.
: Repair harness between hydraulic unit and
ABSCM and check all fuses.
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4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code

B4M0882A
8K24
CHECK GROUND SHORT OF HARNESS.
Measure resistance between ABSCM connector and chas-
sis ground.
: Connector & terminal
(F49) No. 30—Chassis ground
(F49) No. 24—Chassis ground
(F49) No. 23—Chassis ground
(F49) No. 31—Chassis ground
(F49) No. 3—Chassis ground
(F49) No. 51—Chassis ground
(F49) No. 50—Chassis ground
(F49) No. 4—Chassis ground
Is resistance more than 1 MΩ?
: Go to step8K25.
: Repair harness between hydraulic unit and
ABSCM.
B4M0883A
8K25CHECK HARNESS CONNECTOR
BETWEEN ABSCM AND HYDRAULIC
UNIT.
1) Connect connector to hydraulic unit.
2) Measure resistance between ABSCM connector termi-
nals.
: Connector & terminal
(F49) No. 30—No. 1
(F49) No. 24—No. 1
(F49) No. 23—No. 1
(F49) No. 31—No. 1
Is resistance 9.0±0.7Ω?
: Go to next.
: Repair harness connector between hydraulic unit
and ABSCM.
B4M0884A
: Connector & terminal
(F49) No. 3—No. 1
(F49) No. 51—No. 1
(F49) No. 50—No. 1
(F49) No. 4—No. 1
Is resistance 4.8±0.5Ω?
: Go to step8K26.
: Repair harness connector between hydraulic unit
and ABSCM.
87
4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code

8K26CHECK POOR CONTACT IN CONNEC-
TOR BETWEEN ABSCM AND HYDRAU-
LIC UNIT.
: Is there poor contact in connector between
ABSCM and hydraulic unit?
: Repair connector.
: Go to step8K27.
8K27
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.
88
4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code

L: TROUBLE CODE 52
—ABNORMAL MOTOR AND/OR MOTOR
RELAY—
DIAGNOSIS:

Faulty motor

Faulty motor relay

Faulty harness connector
TROUBLE SYMPTOM:

ABS does not operate.
8L1.Check resistance of motor relay.
8L2.Check contact point of motor relay.
8L3.Check short of motor relay.
8L4.Check input voltage of relay box.
8L5.Check input voltage of motor relay.
8L6.Check broken wire in contact point circuit of
relay box.
8L7.Check ground short in contact point circuit of
relay box.
8L8.Check battery short in contact point circuit of
relay box.
8L9.Check broken wire in monitor system circuit of
relay box.
8L10.Check broken wire in control circuit of relay
box.
8L11.Check ground short in control circuit of relay
box.
8L12.Check battery short in control circuit of relay
box.
8L13.Check broken wire in monitor system harness.
8L14.Check broken wire in relay control system
harness.
8L15.Check ground short between relay box and
ABSCM.
Continues to next page.















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4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code

From the former page.
8L16.
Check battery short between relay box and
ABSCM.
8L17.Check ground short at ABSCM monitor
terminal.
8L18.Check battery short at ABSCM monitor
terminal.
8L19.Check motor ground.
8L20.Check ABSCM motor drive terminal.
8L21.Check motor operation.
8L22.Check poor contact in connector between
hydraulic unit, relay box and ABSCM.
8L23.Check ABSCM.








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4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:
B4M1049
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4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code

B4M0886A
8L1
CHECK RESISTANCE OF MOTOR RELAY.
1) Turn ignition switch to OFF.
2) Remove motor relay from relay box.
3) Measure resistance between motor relay terminals.
: Terminals
No. 85—No. 86
Is resistance 80±10Ω?
: Go to step8L2.
: Replace motor relay.
B4M0887A
8L2CHECK CONTACT POINT OF MOTOR
RELAY.
1) Connect battery to motor relay terminals No. 85 and No.
86.
2) Measure resistance between motor relay terminals.
: Terminals
No. 30—No. 87
Is resistance less than 0.5Ω?
: Go to next step.
: Replace motor relay.
B4M0888A
3) Disconnect battery from motor relay terminals.
4) Measure resistance between motor relay terminals.
: Terminals
No. 30—No. 87
Is resistance more than 1 MΩ?
: Go to step8L3.
: Replace motor relay.
92
4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code

B4M0889A
8L3
CHECK SHORT OF MOTOR RELAY.
Measure resistance between motor relay terminals.
: Terminals
No. 85—No. 30
No. 85—No. 87
Is resistance more than 1 MΩ?
: Go to step8L4.
: Replace motor relay.
B4M0890B
8L4CHECK INPUT VOLTAGE OF RELAY
BOX.
1) Disconnect connector (F8) from relay box.
2) Measure voltage between relay box connector and
chassis ground.
: Connector & terminal
(F8) No. 2 (+)—Chassis ground ()
Is voltage 10—13 V?
: Go to step8L5.
: Repair harness connector between battery and
relay box. Check fuse SBF6.
B4M0891
8L5CHECK INPUT VOLTAGE OF MOTOR
RELAY.
1) Connect connector (F8) to relay box.
2) Measure voltage between relay box and chassis
ground.
: Connector & terminal
Relay installing point No. 87 (+)—Chassis
ground ()
Is voltage more than 10 V?
: Go to step8L6.
: Replace relay box. Check fuse SBF6.
93
4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code

B4M0892A
8L6CHECK BROKEN WIRE IN CONTACT
POINT CIRCUIT OF RELAY BOX.
1) Disconnect connector (ABS1) from hydraulic unit.
2) Measure resistance between hydraulic unit and motor
relay installing portion.
: Connector & terminal
(ABS1) No. 1—Motor relay installing por-
tion No. 30
Is resistance less than 0.5Ω?
: Go to step8L7.
: Replace relay box.
B4M0893A
8L7CHECK GROUND SHORT IN CONTACT
POINT CIRCUIT OF RELAY BOX.
Measure resistance between hydraulic unit and chassis
ground.
: Connector & terminal
(ABS1) No. 1—Chassis ground
Is resistance more than 1 MΩ?
: Go to step8L8.
: Replace relay box. Check fuse No. 19.
B4M0793A
8L8CHECK BATTERY SHORT IN CONTACT
POINT CIRCUIT OF RELAY BOX.
1) Disconnect connector from ABSCM.
2) Turn ignition switch to ON.
3) Measure voltage between ABSCM connector and chas-
sis ground.
: Connector & terminal
(ABS1) No. 1 (+)—Chassis ground ()
Is voltage 0 V?
: Go to next step.
: Replace relay box.
4) Turn ignition switch to OFF.
5) Measure voltage between ABSCM connector and chas-
sis ground.
: Connector & terminal
(ABS1) No. 1 (+)—Chassis ground ()
Is voltage 0 V?
: Go to step8L9.
: Replace relay box.
94
4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code

B4M0795B
8L9CHECK BROKEN WIRE IN MONITOR
SYSTEM CIRCUIT OF RELAY BOX.
1) Disconnect connector (F50) from relay box.
2) Measure resistance between relay box connector and
motor relay installing point.
: Connector & terminal
To (F50) No. 6—Motor relay installing point
No. 30
Is resistance less than 0.5Ω?
: Go to step8L10.
: Replace relay box.
B4M0894
8L10CHECK BROKEN WIRE IN CONTROL
CIRCUIT OF RELAY BOX.
1) Remove valve relay from relay box.
2) Measure resistance between motor relay installing point
and valve relay installing point.
: Connector & terminal
Motor relay installing point No. 86—Valve
relay installing point No. 30
Is resistance less than 0.5Ω?
: Go to next step.
: Replace relay box.
95
4-4cBRAKES [ABS 5.3 TYPE]
8. Diagnostics Chart with Trouble Code