Subaru Legacy 2002 Service Manual page 719

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Engine (Diagnostics)
No.
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn ignition switch to OFF.
2) Connect test mode connector at the lower
portion of instrument panel (on the driver's
side), to the side of the center console box.
3) Turn ignition switch to ON.
4) While operating radiator fan relay, measure
voltage between ECM terminal and ground.
NOTE:
Radiator fan relay operation can be executed
using Subaru Select Monitor. For procedure,
refer to "Compulsory Valve Operation Check
Mode". <Ref. to EN-34, Subaru Select Moni-
tor.>
Connector & terminal
(B134) No. 3 (+) — Chassis ground (−):
2 CHECK GROUND SHORT CIRCUIT IN
RADIATOR MAIN FAN RELAY CONTROL
CIRCUIT.
1) Turn ignition switch to OFF.
2) Disconnect connectors from ECM.
3) Measure resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B134) No. 3 — Chassis ground:
3 CHECK POWER SUPPLY FOR RELAY.
1) Remove main fan relay from A/C relay
holder.
2) Turn ignition switch to ON.
3) Measure voltage between fuse and relay
box (F/B) connector and chassis ground.
Connector & terminal
(F66) No. 5 (+) — Chassis ground (−):
4 CHECK MAIN FAN RELAY.
1) Turn ignition switch to OFF.
2) Measure resistance between main fan
relay terminals.
Terminal
No. 5 — No. 6:
5 CHECK OPEN CIRCUIT IN MAIN FAN
RELAY CONTROL CIRCUIT.
Measure resistance of harness between ECM
and main fan relay connector.
Connector & terminal
(B134) No. 3 — (F66) No. 6:
6 CHECK POOR CONTACT.
Check poor contact in ECM or main fan relay
connector.
Step
Does voltage change
between 0 and 10 V?
Is the resistance less than
10 Ω?
Is the voltage more than 10
V?
Is the resistance between
87 and 107 Ω?
Is the resistance less than
1 Ω?
Is there poor contact in
ECM or main fan relay con-
nector?
EN-202
Check Yes
Repair poor con-
tact in ECM con-
nector.
Repair ground
short circuit in
radiator main fan
relay control cir-
cuit.
Go to step 4.
Go to step 5.
Go to step 6.
Repair poor con-
tact in ECM or
main fan relay
connector.
No
Go to step 2.
Go to step 3.
Repair open cir-
cuit in harness
between ignition
switch and fuse
and relay box
(F/B) connector.
Replace main fan
relay.
Repair harness
and connector.
NOTE:
In this case,
repair the follow-
ing:
¼ Open circuit in
harness between
ECM and main
fan relay connec-
tor
¼ Poor contact in
coupling connec-
tor (F45)
Contact with your
Subaru distributor
service.