Subaru Legacy III (2000-2003 year). Service manual — part 439
CO(H4DOSTC)-10
COOLING
RADIATOR MAIN FAN SYSTEM
NOTE:
Inspection by distributor service is required, because probable cause is deterioration of multiple parts.
13
CHECK HARNESS BETWEEN MAIN FAN
RELAY AND ECM.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between
main fan relay connector and ECM connec-
tor.
Connector & terminal
(F66) No. 7 — (B134) No. 14:
Is the measured value less than the speci-
fied valve?
1
Ω
Repair open circuit
in harness
between main fan
relay and ECM.
14
CHECK POOR CONTACT.
Check poor contact in connector between main
fan and ECM.
Is there poor contact in connector between
main fan motor and ECM?
There is poor contact.
Repair poor con-
tact connector.
Contact with dis-
tributor service.
Step
Value
Yes
No
CO(H4DOSTC)-11
COOLING
RADIATOR SUB FAN SYSTEM
3. Radiator Sub Fan System
A: SCHEMATIC
CO-00146
2
1
4
3
21
22
24
20
8
7
5
9
20A
20A
SUB FAN
RELAY
AIR CONDITIONING RELAY HOLDER
SUB FAN
MOTOR
MAIN FAN
MOTOR
MAIN FAN
RELAY
F28
F16
F66
F27
1
2
F17
B100
F2
B72
1
2
8
9
NO. 3
NO. 18
NO. 17
SBF-4
SBF-1
IGNITION
SWITCH
B72
3 4
1 2
B137
BATTERY
17
28
B137
ECM
F16
F17
2 1
F27
1
2
3
4
5 6 7
8
9
11
10
13
12
14
21
20
23
22
24
31
30
33
32
34
16
15
17
18
19
26
25
27
28
29
35
36
F66
F28
F2
1
2 3 4
5 6 7
9 10 11 12 13 14 15 16
8
1
2
7
8
9
5
6
3
4
10
11
12
19
20
21
29
30
31
13
14
15
16
17
27
28
18
22
23
24
25
26
CO(H4DOSTC)-12
COOLING
RADIATOR SUB FAN SYSTEM
B: INSPECTION
NOTE:
Radiator sub fan system is for model with A/C.
DETECTING CONDITION:
Condition (1):
• Engine coolant temperature is below 95
°
C (203
°
F).
• A/C switch is turned ON.
• Vehicle speed is below 19 km/h (12 MPH).
Condition (2):
• Engine coolant temperature is above 100
°
C (212
°
F).
• A/C switch is turned OFF.
• Vehicle speed is below 19 km/h (12 MPH).
TROUBLE SYMPTOM:
• Radiator sub fan does not rotate under conditions (1) and (2) above.
Step
Value
Yes
No
1
CHECK POWER SUPPLY TO SUB FAN MO-
TOR.
CAUTION:
Be careful not to overheat engine during re-
pair.
1) Turn ignition switch to OFF.
2) Disconnect connector from sub fan motor
and main fan motor.
3) Start the engine, and warm it up until
engine coolant temperature increases over
100
°
C (212
°
F).
4) Stop the engine and turn ignition switch to
ON.
5) Measure voltage between sub fan motor
connector and chassis ground.
Connector & terminal
(F16) No. 2 (+) — Chassis ground (
−−−−
):
Does the measured value exceed the spec-
ified value?
10 V
2
CHECK GROUND CIRCUIT OF SUB FAN
MOTOR.
1) Turn ignition switch to OFF.
2) Measure resistance between sub fan motor
connector and chassis ground.
Connector & terminal
(F16) No. 1 — Chassis ground:
Is the measured value less than the speci-
fied valve?
5
Ω
Repair open circuit
in harness
between sub fan
motor connector
and chassis
ground.
3
CHECK POOR CONTACT.
Check poor contact in sub fan motor connec-
tor.
Is there poor contact in sub fan motor connec-
tor?
Repair poor con-
tact in sub fan
motor connector.
4
CHECK SUB FAN MOTOR.
Connect battery positive (+) terminal to termi-
nal No. 2, and negative (
−
) terminal to terminal
No. 1 of sub fan motor connector.
Does the sub fan rotate?
Sub fan rotates.
Repair poor con-
tact in sub fan
motor connector.
Replace sub fan
motor with a new
one.
CO(H4DOSTC)-13
COOLING
RADIATOR SUB FAN SYSTEM
5
CHECK POWER SUPPLY TO SUB FAN RE-
LAY.
1) Turn ignition switch to OFF.
2) Remove sub fan relay from A/C relay
holder.
3) Measure voltage between sub fan relay ter-
minal and chassis ground.
Connector & terminal
(F28) No. 21 (+) — Chassis ground (
−−−−
):
Does the measured value exceed the spec-
ified value?
10 V
6
CHECK POWER SUPPLY TO SUB FAN RE-
LAY.
1) Turn ignition switch to ON.
2) Measure voltage between sub fan relay ter-
minal and chassis ground.
Connector & terminal
(F28) No. 24 (+) — Chassis ground (
−−−−
):
Does the measured value exceed the spec-
ified value?
10 V
7
CHECK 20 A FUSE.
1) Remove 20 A fuse from A/C relay holder.
2) Check condition of fuse.
Is the fuse blown-out?
Fuse is blown-out.
Replace fuse.
8
CHECK POWER SUPPLY TO A/C RELAY
HOLDER 20 A FUSE TERMINAL.
Measure voltage of harness between A/C relay
holder 20 A fuse terminal and chassis ground.
Connector & terminal
(F27) No. 3 (+) — Chassis ground (
−−−−
):
Does the measured value exceed the specified
value?
10 V
Repair open circuit
in harness
between 20 A fuse
and sub fan relay
terminal.
Repair open circuit
in harness
between main fuse
box connector and
20 A fuse terminal.
9
CHECK FUSE.
1) Turn ignition switch to OFF.
2) Remove fuse No. 17 from joint box.
3) Check condition of fuse.
Is the fuse blown-out?
Fuse is blown-out.
Replace fuse.
Repair open circuit
in harness
between sub fan
relay and ignition
switch.
10
CHECK SUB FAN RELAY.
1) Turn ignition switch to OFF.
2) Measure resistance of sub fan relay.
Terminal
No. 20 — No. 21:
Does the measured value exceed the spec-
ified value?
1 M
Ω
Replace sub fan
relay.
11
CHECK SUB FAN RELAY.
1) Connect battery to terminals No. 22 and
No. 24 of sub fan relay.
2) Measure resistance of sub fan relay.
Terminal
No. 20 — No. 21:
Is the measured value less than the speci-
fied valve?
1
Ω
Replace sub fan
relay.
Step
Value
Yes
No
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