Subaru Impreza 2003 Service Manual page 330

COOLING
B: INSPECTION
DETECTING CONDITION:
• Engine coolant temperature is above 96°C (205°F).
• Vehicle speed is below 19 km/h (12 MPH).
TROUBLE SYMPTOM:
• Radiator main fan does not rotate under the above conditions.
Step
1 CHECK POWER SUPPLY TO MAIN FAN MO-
TOR.
CAUTION:
Be careful not to overheat the engine during
repair.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from main fan
motor.
3)Start the engine, and warm it up until engine
coolant temperature increases over 96°C
(205°F).
4)Stop the engine and turn ignition switch to
ON.
5)Measure the voltage between main fan
motor connector and chassis ground.
Connector & terminal
(F17) No. 2 (+) — Chassis ground ( − − − − ):
2 CHECK GROUND CIRCUIT OF MAIN FAN
MOTOR.
1)Turn the ignition switch to OFF.
2)Measure the resistance between main fan
motor connector and chassis ground.
Connector & terminal
(F17) No. 1 — Chassis ground:
3 CHECK POOR CONTACT.
Check poor contact in main fan motor connec-
tor.
4 CHECK MAIN FAN MOTOR.
Connect the battery positive (+) terminal to ter-
minal No. 2, and ground (−) terminal to termi-
nal No. 1 of main fan motor connector.
5 CHECK POWER SUPPLY TO MAIN FAN RE-
LAY.
1)Turn the ignition switch to OFF.
2)Remove the main fan relay from A/C relay
holder.
3)Measure the voltage between main fan relay
terminal and chassis ground.
Connector & terminal
(F27) No. 26 (+) — Chassis ground ( − − − − ):
6 CHECK POWER SUPPLY TO MAIN FAN RE-
LAY.
1)Turn the ignition switch to ON.
2)Measure the voltage between main fan relay
terminal and chassis ground.
Connector & terminal
(F27) No. 28 (+) — Chassis ground ( − − − − ):
7 CHECK 20 A FUSE.
1)Remove the 20 A fuse from A/C relay holder.
2)Check the condition of fuse.
RADIATOR MAIN FAN SYSTEM
Is the voltage more than 10 V? Go to step 2.
Is the resistance less than 5
Ω?
Is there poor contact in main
fan motor connector?
Does the main fan rotate?
Is the voltage more than 10 V? Go to step 6.
Is the voltage more than 10 V? Go to step 10.
Is the fuse blown out?
CO(H4SO)-8
Check
Go to step 3.
Repair the poor
contact in main fan
motor connector.
Repair the poor
contact in main fan
motor connector.
Replace the fuse.
Yes No
Go to step 5.
Repair the open
circuit in harness
between main fan
motor connector
and chassis
ground.
Go to step 4.
Replace the main
fan motor with a
new one.
Go to step 7.
Go to step 9.
Go to step 8.