power supply circuit SUBARU LEGACY 1995 Service Repair Manual

A: OPERATION (WITHOUT A/C MODEL)
CONDITION:
Engine coolant temperature is above 95°C (203°F).
TROUBLE SYMPTOM:
Radiator main fan does not operate under the above
condition.
1. Check fuse and power supply.
OK
Not OK
Melted fuse,repair the shorted part of the circuit
,replace fuse.
2. Check harness connector between fuse and
relay box, and A/C relay holder.
OK
Not OK
Repair or replace wiring harness.
3. Check A/C relay holder.
OK
Not OK
Repair or replace A/C relay holder.
4. Check harness connector between A/C relay
holder and main fan motor.
OK
Not OK
Repair or replace wiring harness.
5. Check ground circuit of main fan motor.
OK
Not OK
Repair or replace wiring harness.
6. Check main fan motor.
OK
Not OK
Replace main fan motor.
Refer to 2-7 On-Board Diagnostics II System.
B2M0427A
1. CHECK FUSE AND POWER SUPPLY.
1) Check fuse No. 13.
2) Turn ignition switch to ACC.
3) Measure voltage between fuse and relay box, and body.
Connector & terminal / Specified voltage:
(F40) No. 3—Body / 10 V, or more






21
2-5DIAGNOSTICS
2. Radiator Main Fan

B: LO MODE OPERATION (WITH A/C MODEL)
CONDITION:
Condition (1) :
Engine coolant temperature is below 89°C (192°F).
A/C switch is turned ON.
Vehicle speed is below 10 km/h (6 MPH).
Condition (2) :
Engine coolant temperature is above 95°C (203°F).
A/C switch is turned OFF.
Vehicle speed is below 10 km/h (6 MPH).
TROUBLE SYMPTOM:
Radiator main fan does not rotate at LO speed under
conditions (1) and (2) above.
1. Check power supply to main fan relay-1.
OK
Not OK
Melted fuse (in A/C relay holder),repair the
shorted part of the circuit,replace fuse.
2. Check main fan relay-1.
OK
Not OK
Replace main fan relay-1.
3. Check harness connector between main fan
relay-1 and main fan motor.
OK
Not OK
Repair or replace wiring harness.
4. Check ground circuit of main fan motor.
OK
Not OK
Repair or replace wiring harness.
5. Check main fan motor.
OK
Not OK
Replace main fan motor.
Refer to 2-7 On-Board Diagnostics II System.





23
2-5DIAGNOSTICS
2. Radiator Main Fan

C: HI MODE OPERATION (WITH A/C MODEL)
CONDITION:
Condition (1) :
Engine coolant temperature is below 89°C (192°F).
A/C switch is turned ON.
Vehicle speed is over 20 km/h (12 MPH).
Condition (2) :
Engine coolant temperature is above 95°C (203°F).
A/C switch is turned OFF.
Vehicle speed is over 20 km/h (12 MPH).
Condition (3) :
Engine coolant temperature is above 95°C (203°F).
A/C switch is turned ON.
TROUBLE SYMPTOM:
Radiator main fan does not rotate at HI speed under
conditions (1), (2) and (3) above.
1. Check operation of main fan motor LO mode.
OK
Not OK
Check LO mode operation.
2. Check power supply to main fan relay-2.
OK
Not OK
Melted fuse (in A/C relay holder),repair the
shorted part of the circuit,replace fuse.
3. Check main fan relay-2.
OK
Not OK
Replace main fan relay-2.
4. Check harness connector between main fan
relay-2 and main fan motor.
OK
Not OK
Repair or replace wiring harness.
5. Check ground circuit of main fan motor.
OK
Not OK
Repair or replace wiring harness.
6. Check main fan motor.
OK
Not OK
Replace main fan motor.
Refer to 2-7 On-Board Diagnostics II System.






26
2-5DIAGNOSTICS
2. Radiator Main Fan

A: LO MODE OPERATION
CONDITION:
Condition (1) :
Engine coolant temperature is below 89°C (192°F).
A/C switch is turned ON.
Vehicle speed is below 10 km/h (6 MPH).
Condition (2) :
Engine coolant temperature is above 95°C (203°F).
A/C switch is turned OFF.
Vehicle speed is below 10 km/h (6 MPH).
TROUBLE SYMPTOM:
Radiator sub fan does not rotate at LO speed under
conditions (1) and (2) above.
1. Check fuse and power supply.
OK
Not OK
Melted fuse,repair the shorted part of the circuit
,replace fuse.
2. Check harness connector between fuse and
relay box, and sub fan motor.
OK
Not OK
Repair or replace wiring harness.
3. Check ground circuit of sub fan motor.
OK
Not OK
Repair or replace wiring harness.
4. Check sub fan motor.
OK
Not OK
Replace sub fan motor.
Refer to 2-7 On-Board Diagnostics II System.




30
2-5DIAGNOSTICS
3. Radiator Sub Fan (With A/C model only)

B2M0427A
1. CHECK FUSE AND POWER SUPPLY.
1) Check fuse No. 13.
2) Turn ignition switch to ACC.
3) Measure voltage between fuse and relay box, and body.
Connector & terminal / Specified voltage:
(F40) No. 3—Body / 10 V, or more
B2M0377A
2. CHECK HARNESS CONNECTOR BETWEEN FUSE
AND RELAY BOX, AND SUB FAN MOTOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from fuse and relay box, and
sub fan motor.
3) Measure resistance of harness connector between fuse
and relay box, and sub fan motor.
Connector & terminal / Specified resistance:
(F40) No. 3—(F16) No. 2 / 10Ω, max.
B2M0378A
3. CHECK GROUND CIRCUIT OF SUB FAN MOTOR.
Measure resistance between sub fan motor connector and
body.
Connector & terminal / Specified resistance:
(F16) No. 1—Body / 10Ω, max.
B2M0372A
4. CHECK SUB FAN MOTOR.
1) Disconnect connector from sub fan motor.
2) Connect battery positive (+) terminal to terminal No. 2
and connect terminal No. 1 to ground. Ensure that fan
rotates at LO speed.
31
2-5DIAGNOSTICS
3. Radiator Sub Fan (With A/C model only)

B: HI MODE OPERATION
CONDITION:
Condition (1) :
Engine coolant temperature is below 89°C (192°F).
A/C switch is turned ON.
Vehicle speed is over 20 km/h (12 MPH).
Condition (2) :
Engine coolant temperature is above 95°C (203°F).
A/C switch is turned OFF.
Vehicle speed is over 20 km/h (12 MPH).
Condition (3) :
Engine coolant temperature is above 95°C (203°F).
A/C switch is turned ON.
TROUBLE SYMPTOM:
Radiator sub fan does not rotate at HI speed under con-
ditions (1), (2) and (3) above.
1. Check operation of sub fan motor LO mode.
OK
Not OK
Check LO mode operation.
2. Check power supply to sub fan relay-2.
OK
Not OK
Melted fuse (in A/C relay holder),repair the
shorted part of the circuit,replace fuse.
3. Check sub fan relay-2.
OK
Not OK
Replace sub fan relay-2.
4. Check harness connector between sub fan
relay-2 and sub fan motor.
OK
Not OK
Repair or replace wiring harness.
5. Check ground circuit of sub fan motor.
OK
Not OK
Repair or replace wiring harness.
6. Check sub fan motor.
OK
Not OK
Replace sub fan motor.
Refer to 2-7 On-Board Diagnostics II System.






32
2-5DIAGNOSTICS
3. Radiator Sub Fan (With A/C model only)

B6M0489A
1) Diodes on“+”side
Continuity of proper diodes on“+”side
BAT side
(+) ()
Terminal
N, U, V and W
(+)—Continuity must
not exist.
()Continuity
must exist.—
B6M0490A
2) Diodes on“”side
Continuity of proper diodes on“”side
“E”side
(+) ()
Terminal
N, U, V and W
(+)—Continuity must
exist.
()Continuity
must not exist.—
CAUTION:
Never use a high tension insulation tester, such as a
meggar as it will damage diodes with its high tension.
B6M0491A
5. IC REGULATOR
1) Compose a circuit diagram as shown in figure.


1Voltage meter: 0 to 30 V


2Switch 1


3Variable DC power supply: Variable 0 to 20 V, 1 A or
more


4Lamp 2


5Lamp 1


6Switch 3


7Switch 2


8Plus generator: Power supply 5 to 30 V, 1 kHz
20
6-1SERVICE PROCEDURE
2. Generator

1. Starter Interlock System (MT Model)
A: DIAGNOSTICS PROCEDURE
1. Check main power supply for starter motor.
OK
Not OK

Recharge the battery.

Repair or replace wiring harness.
2. Check power supply for magnet coil of starter
motor.
Not OK
OK
Repair or replace starter motor.
3. Check power supply for starter interlock relay.
OK
Not OK
Repair or replace wiring harness.
4. Check starter interlock relay.
OK
Not OK
Replace starter interlock relay.
5. Check clutch switch.
OK
Not OK
Adjust or replace clutch switch.
6. Check harness connector between starter
interlock relay and starter motor.
OK
Not OK
Repair or replace wiring harness.
7. Check harness connector between starter
interlock relay and clutch switch.
OK
Not OK
Repair or replace wiring harness.
8. Check ground circuit of clutch switch.
OK
Not OK
Repair or replace wiring harness.
System is OK








61
6-2DIAGNOSTICS
1. Starter Interlock System (MT Model)

3. Combination Meter
A: DIAGNOSTICS PROCEDURE
If speedometer does not operate, or operates abnormally,
check combination meter circuit (shown in flow chart as
described below).
CAUTION:
Make sure that trouble code of vehicle speed sensor 2
system appears in electrical system on-board diagno-
sis.
Speedometer does not operate, or operates
abnormally.
1. Check power supply for combination meter.
OK
Not OK

Check for disconnection of the combination meter
connector terminal.

Check for open circuit between combination meter
and battery.
,Repair or replace wiring harness.
2. Check ground circuit of combination meter.
OK
Not OK
Repair or replace wiring harness.
3. Check harness connector between
combination meter and vehicle speed sensor
2.
OK
Not OK
Repair or replace wiring harness.
4. Check vehicle speed sensor 2.
OK
Not OK
Replace vehicle speed sensor 2.
Failure of the speedometer.





70
6-2DIAGNOSTICS
3. Combination Meter

B6M0530A
1. CHECK POWER SUPPLY FOR COMBINATION
METER.
1) Remove combination meter.
2) Turn ignition switch to ON.
3) Measure voltage at combination meter connector termi-
nal.
Connector & terminal / Specified voltage:
(i14) No. 11—Body / 10 V, or more
B6M0252B
2. CHECK GROUND CIRCUIT OF COMBINATION
METER.
1) Turn ignition switch to OFF.
2) Measure resistance of harness connector between
combination meter and body.
Connector & terminal / Specified voltage:
(i12) No. 1—Body / 10Ω, max.
B6M0294B
3. CHECK HARNESS CONNECTOR BETWEEN
COMBINATION METER AND VEHICLE SPEED
SENSOR 2.
1) Disconnect connector from vehicle speed sensor 2.
2) Measure resistance of harness connector between
vehicle speed sensor 2 and combination meter.
Connector & terminal / Specified resistance:
(B17) No. 1—(i11)No.2/10Ω, max.
(B17) No. 2—(i11)No.3/10Ω, max.
4. CHECK VEHICLE SPEED SENSOR 2.
NOTE:

If resistance between terminals of vehicle speed sensor
2 is out of specification, the sensor may have a failure.

If resistance is OK and voltage between terminals of
vehicle speed sensor 2 is out of specification, mechanical
trouble may be present between vehicle speed sensor 2
and speedometer shaft in transmission.
71
6-2DIAGNOSTICS
3. Combination Meter