Subaru Legacy 2003 Service Manual page 641

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
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 and chassis 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(H4SO)-48, Compulsory
Valve Operation Check Mode.>
Connector & terminal
(B134) No. 14 (+) — Chassis ground ( − − − − ):
(B134) No. 13 (+) — Chassis ground ( − − − − ):
Does the measured value change within
specified range?
2 CHECK SHORT CIRCUIT IN RADIATOR FAN
RELAY CONTROL CIRCUIT.
1) Turn ignition switch to OFF.
2) Remove main fan relay and sub fan relay.
(with A/C models)
3) Disconnect test mode connector.
4) Turn ignition switch to ON.
5) Measure voltage between ECM and chas-
sis ground.
Connector & terminal
(B134) No. 14 (+) — Chassis ground ( − − − − ):
(B134) No. 13 (+) — Chassis ground ( − − − − ):
Does the measured value exceed the spec-
ified value?
3 CHECK MAIN FAN RELAY.
1) Turn ignition switch to OFF.
2) Remove main fan relay.
3) Measure resistance between main fan relay
terminals.
Terminal
No. 5 — No. 7:
Is the measured value less than the speci-
fied value?
4 CHECK SUB FAN RELAY.
1) Remove sub fan relay.
2) Measure resistance between sub fan relay
terminals.
Terminal
No. 22 — No. 24
Is the measured value less than the speci-
fied value?
5 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Is there poor contact in ECM connector?
Step
EN(H4SO)-244
Value
0 - 10 V
10 V
1 Ω
1 Ω
There is poor contact.
Yes
Even if MI lights Go to step 2.
up, the circuit has
returned to a nor-
mal condition at
this time. In this
case, repair poor
contact in ECM
connector.
Repair battery Go to step 3.
short circuit in radi-
ator fan relay con-
trol circuit.
Replace main fan Go to step 4.
relay.
Replace sub fan Go to step 5.
relay.
Repair poor con- Replace ECM.
tact in ECM con- <Ref. to
nector. FU(H4SO)-45,
Engine Control
Module.>
No