Subaru Impreza 2003 Service Manual page 331

Step
8 CHECK POWER SUPPLY TO A/C RELAY
HOLDER 20 A FUSE TERMINAL.
Measure the voltage of harness between A/C
relay holder 20 A fuse terminal and chassis
ground.
Connector & terminal
(F27) No. 1 (+) — Chassis ground ( − − − − ):
9 CHECK FUSE.
1)Turn the ignition switch to OFF.
2)Remove the fuse No. 18 from joint box.
3)Check the condition of fuse.
10 CHECK MAIN FAN RELAY.
1)Turn the ignition switch to OFF.
2)Remove the main fan relay.
3)Measure the resistance of main fan relay.
Terminal
No. 26 — No. 25:
11 CHECK MAIN FAN RELAY.
1)Connect the battery to terminals No. 27 and
No. 28 of main fan relay.
2)Measure the resistance of main fan relay.
Terminal
No. 26 — No. 25:
12 CHECK HARNESS BETWEEN MAIN FAN
RELAY TERMINAL AND MAIN FAN MOTOR
CONNECTOR.
Measure the resistance of harness between
main fan motor connector and main fan relay
terminal.
Connector & terminal
(F17) No. 2 — (F27) No. 25:
13 CHECK HARNESS BETWEEN MAIN FAN
RELAY AND ECM.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from ECM.
3)Measure the resistance of harness between
main fan relay connector and ECM connector.
Connector & terminal
With OBD:
(F27) No. 27 — (B134) No. 14:
Without OBD:
(F27) No. 27 — (B134) No. 3:
14 CHECK POOR CONTACT.
Check poor contact in connector between main
fan and ECM.
RADIATOR MAIN FAN SYSTEM
Is the voltage more than 10 V? Repair the open
Is the fuse blown out?
Is the resistance more than 1
MΩ?
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is there poor contact in con-
nector between main fan motor
and ECM?
CO(H4SO)-9
Check
circuit in harness
between 20 A fuse
and main fan relay
terminal.
Replace the fuse.
Go to step 11.
Go to step 12.
Go to step 13.
Go to step 14.
Repair the poor
contact connector.
COOLING
Yes No
Repair the open
circuit in harness
between main fuse
box connector and
20 A fuse terminal.
Repair the open
circuit in harness
between main fan
relay and ignition
switch.
Replace the main
fan relay.
Replace the main
fan relay.
Repair the open
circuit in harness
between main fan
motor connector
and main fan relay
terminal.
Repair the open
circuit in harness
between main fan
relay and ECM.
Verify the DTC.
Repair the trouble
cause. <Ref. to
EN(H4SO)-38,
Read Diagnostic
Trouble Code
(DTC).>, <Ref. to
EN(H4SOw/
oOBD)-24, Read
Diagnostic Trou-
ble Code (DTC).>