1997 SUBARU LEGACY battery

1. Supplemental Restraint System
“Airbag”
Airbag system wiring harness is routed near the ABS
sensor, ABS control module and hydraulic control unit.
CAUTION:

All Airbag system wiring harness and connectors
are colored yellow. Do not use electrical test equip-
ment on these circuit.

Be careful not to damage Airbag system wiring har-
ness when servicing the ABS sensor, ABS control
module and hydraulic control unit.
2. Pre-inspection
Before performing diagnostics, check the following items
which might affect ABS problems:
A: MECHANICAL INSPECTION
1. POWER SUPPLY
1) Measure battery voltage and specific gravity of electro-
lyte.
Standard voltage: 12 V, or more
Specific gravity: Above 1.260
2) Check the condition of the main and other fuses, and
harnesses and connectors. Also check for proper ground-
ing.
2. BRAKE FLUID
1) Check brake fluid level.
2) Check brake fluid leakage.
3. BRAKE DRAG
Check brake drag.
4. BRAKE PAD AND ROTOR
Check brake pad and rotor.
5. TIRE SPECIFICATIONS, TIRE WEAR AND AIR
PRESSURE
Check tire specifications, tire wear and air pressure. to 4-2 [S1A1], 4-2 [S1A2].>
2
4-4dBRAKES [ABS 5.3i TYPE]
1. Supplemental Restraint System“Airbag”- 2. Pre-inspection

1. Supplemental Restraint System
“Airbag”
Airbag system wiring harness is routed near the ABS
sensor, ABS control module and hydraulic control unit.
CAUTION:

All Airbag system wiring harness and connectors
are colored yellow. Do not use electrical test equip-
ment on these circuit.

Be careful not to damage Airbag system wiring har-
ness when servicing the ABS sensor, ABS control
module and hydraulic control unit.
2. Pre-inspection
Before performing diagnostics, check the following items
which might affect ABS problems:
A: MECHANICAL INSPECTION
1. POWER SUPPLY
1) Measure battery voltage and specific gravity of electro-
lyte.
Standard voltage: 12 V, or more
Specific gravity: Above 1.260
2) Check the condition of the main and other fuses, and
harnesses and connectors. Also check for proper ground-
ing.
2. BRAKE FLUID
1) Check brake fluid level.
2) Check brake fluid leakage.
3. BRAKE DRAG
Check brake drag.
4. BRAKE PAD AND ROTOR
Check brake pad and rotor.
5. TIRE SPECIFICATIONS, TIRE WEAR AND AIR
PRESSURE
Check tire specifications, tire wear and air pressure. to 4-2 [S1A1], 4-2 [S1A2].>
2
4-4dBRAKES [ABS 5.3i TYPE]
1. Supplemental Restraint System“Airbag”- 2. Pre-inspection

7A1CHECK IF OTHER WARNING LIGHTS
TURN ON.
Turn ignition switch to ON (engine OFF).
: Do other warning lights turn on?
: Go to step7A2.
: Repair combination meter.
7A2
CHECK ABS WARNING LIGHT BULB.
1) Turn ignition switch to OFF.
2) Remove combination meter.
3) Remove ABS warning light bulb from combination
meter.
: Is ABS warning light bulb OK?
: Go to step7A3.
: Replace ABS warning light bulb.
B4M1273A
7A3CHECK BATTERY SHORT OF ABS
WARNING LIGHT HARNESS.
1) Disconnect connector (B100) from connector (F2).
2) Measure voltage between connector (B100) and chas-
sis ground.
Connector & terminal
(B100) No. 9 (+) — Chassis ground ():
: Is the voltage less than 3 V?
: Go to step7A4.
: Repair warning light harness.
17
4-4dBRAKES [ABS 5.3i TYPE]
7. Diagnostics Chart for ABS Warning Light Circuit and Diagnosis Circuit Failure

B4M1273A
7A4CHECK BATTERY SHORT OF ABS
WARNING LIGHT HARNESS.
1) Turn ignition switch to ON.
2) Measure voltage between connector (B100) and chas-
sis ground.
Connector & terminal
(B100) No. 9 (+)—Chassis ground ():
: Is voltage less than 3 V?
: Go to step7A5.
: Repair warning light harness.
B4M1273A
7A5
CHECK WIRING HARNESS.
1) Turn ignition switch to OFF.
2) Install ABS warning light bulb from combination meter.
3) Install combination meter.
4) Turn ignition switch to ON.
5) Measure voltage between connector (B100) and chas-
sis ground.
Connector & terminal
(B100) No. 9 (+)—Chassis ground ():
: Is voltage between 10 V and 15 V?
: Go to step7A6.
: Repair wiring harness.
18
4-4dBRAKES [ABS 5.3i TYPE]
7. Diagnostics Chart for ABS Warning Light Circuit and Diagnosis Circuit Failure

B4M1274A
7A6CHECK BATTERY SHORT OF ABS
WARNING LIGHT HARNESS.
1) Turn ignition switch to OFF.
2) Measure voltage between connector (F2) and chassis
ground.
Connector & terminal
(F2) No. 9 (+)—Chassis ground ():
: Is the voltage less than 3 V?
: Go to step7A7.
: Repair wiring harness.
B4M1274A
7A7CHECK BATTERY SHORT OF ABS
WARNING LIGHT HARNESS.
1) Turn ignition switch to ON.
2) Measure voltage between connector (F2) and chassis
ground.
Connector & terminal
(F2) No. 9 (+)—Chassis ground ():
: Is voltage less than 3 V?
: Go to step7A8.
: Repair wiring harness.
B4M1243A
7A8CHECK GROUND CIRCUIT OF
ABSCM&H/U.
Measure resistance between ABSCM&H/U and chassis
ground.
Connector & terminal
(F49) No. 23—GND:
: Is the resistance less than 0.5Ω?
: Go to step7A9.
: Repair ABSCM&H/U ground harness.
19
4-4dBRAKES [ABS 5.3i TYPE]
7. Diagnostics Chart for ABS Warning Light Circuit and Diagnosis Circuit Failure

B4M0430
7B4
CHECK GENERATOR.
1) Start the engine.
2) Idle the engine.
3) Measure voltage between generator and chassis
ground.
Terminal
Generator B terminal (+)—Chassis ground ():
: Is the voltage between 10 and 15 V?
: Go to step7B5.
: Repair generator.
7B5
CHECK BATTERY TERMINAL.
Turn ignition switch to OFF.
: Is there poor contact at battery terminal?
: Repair battery terminal.
: Go to step7B6.
B4M1234A
7B6
CHECK POWER SUPPLY OF ABSCM.
1) Disconnect connector from ABSCM&H/U.
2) Start engine.
3) Idle the engine.
4) Measure voltage between ABSCM&H/U connector and
chassis ground.
Connector & terminal
(F49) No. 1 (+)—Chassis ground ():
: Is the voltage between 10 and 15 V?
: Go to step7B7.
: Repair ABSCM&H/U power supply circuit.
7B7
CHECK WIRING HARNESS.
1) Disconnect connector (F2) from connector (B100).
2) Turn ignition switch to ON.
: Does the ABS warning light remain off?
: Go to step7B8.
: Repair front wiring harness.
B4M1235A
7B8
CHECK PROJECTION AT ABSCM&H/U.
1) Turn ignition switch to OFF.
2) Check for broken projection at the ABSCM&H/U termi-
nal.
: Are the projection broken?
: Go to step7B9.
: Replace ABSCM&H/U.
23
4-4dBRAKES [ABS 5.3i TYPE]
7. Diagnostics Chart for ABS Warning Light Circuit and Diagnosis Circuit Failure

B4M0806E
B4M1036C
8E1
CHECK ABS SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ABS sensor.
3) Measure resistance of ABS sensor connector terminals.
Terminal
Front RH No. 1—No. 2:
Front LH No. 1—No. 2:
Rear RH No. 1—No. 2:
Rear LH No. 1—No. 2:
: Is the resistance between 0.8 and 1.2 kΩ?
: Go to step8E2.
: Replace ABS sensor.
B4M0807E
B4M1037C
8E2CHECK BATTERY SHORT OF ABS SEN-
SOR.
1) Disconnect connector from ABSCM&H/U.
2) Measure voltage between ABS sensor and chassis
ground.
Terminal
Front RH No. 1 (+)—Chassis ground ():
Front LH No. 1 (+)—Chassis ground ():
Rear RH No. 1 (+)—Chassis ground ():
Rear LH No. 1 (+)—Chassis ground ():
: Is the voltage less than 1 V?
: Go to step8E3.
: Replace ABS sensor.
29
4-4dBRAKES [ABS 5.3i TYPE]
8. Diagnostics Chart with Trouble Code by ABS Warning Light

B4M0807E
B4M1037C
8E3CHECK BATTERY SHORT OF ABS SEN-
SOR.
1) Turn ignition switch to ON.
2) Measure voltage between ABS sensor and chassis
ground.
Terminal
Front RH No. 1 (+)—Chassis ground ():
Front LH No. 1 (+)—Chassis ground ():
Rear RH No. 1 (+)—Chassis ground ():
Rear LH No. 1 (+)—Chassis ground ():
: Is the voltage less than 1 V?
: Go to step8E4.
: Replace ABS sensor.
B4M1239A
8E4CHECK HARNESS/CONNECTOR
BETWEEN ABSCM&H/U AND ABS SEN-
SOR.
1) Turn ignition switch to OFF.
2) Connect connector to ABS sensor.
3) Measure resistance between ABSCM&H/U connector
terminals.
Connector & terminal
Trouble code 21 / (F49) No. 11—No. 12:
Trouble code 23 / (F49) No. 9—No. 10:
Trouble code 25 / (F49) No. 14—No. 15:
Trouble code 27 / (F49) No. 7—No. 8:
: Is the resistance between 0.8 and 1.2 kΩ?
: Go to step8E5.
: Repair harness/connector between ABSCM&H/U
and ABS sensor.
30
4-4dBRAKES [ABS 5.3i TYPE]
8. Diagnostics Chart with Trouble Code by ABS Warning Light