Subaru IMPREZA 2004 Service Manual page 133

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK OUTPUT SIGNAL FROM ECM.
1)Turn the ignition switch to OFF.
2)Connect the test mode connector at the
lower portion of instrument panel (on the
drive's side).
3)Turn the ignition switch to ON.
4)While operating the radiator fan relay, mea-
sure 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)(diag)-48, Compul-
sory Valve Operation Check Mode.>
Connector & terminal
(B134) No. 14 (+) — Chassis ground ( − − − − ):
(B134) No. 13 (+) — Chassis ground ( − − − − ):
2 CHECK SHORT CIRCUIT IN RADIATOR FAN
RELAY CONTROL CIRCUIT.
1)Turn the ignition switch to OFF.
2)Remove the main fan relay and sub fan relay.
(with A/C models)
3)Disconnect the test mode connector.
4)Turn the ignition switch to ON.
5)Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 14 (+) — Chassis ground ( − − − − ):
(B134) No. 13 (+) — Chassis ground ( − − − − ):
3 CHECK MAIN FAN RELAY.
1)Turn the ignition switch to OFF.
2)Remove the main fan relay.
3)Measure the resistance between main fan
relay terminals.
Terminal
No. 30 — No. 31:
4 CHECK SUB FAN RELAY.
1)Remove the sub fan relay.
2)Measure the resistance between sub fan
relay terminals.
Terminal
No. 20 — No. 21:
5 CHECK POOR CONTACT.
Check poor contact in ECM connector.
Check
Is the voltage 0 — 10 V?
Is the voltage more than 10 V? Repair battery
Is the resistance less than 1
Ω?
Is the resistance less than 1
Ω?
Is there poor contact in ECM
connector?
EN(H4SO)(diag)-210
Yes
Even if malfunction Go to step 2.
indicator light
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time. In
this case, repair
poor contact in
ECM connector.
Go to step 3.
short circuit in
radiator fan relay
control circuit.
After repair,
replace the ECM.
<Ref. to
FU(H4SO)-47,
Engine Control
Module (ECM).>
Replace the main Go to step 4.
fan relay and
ECM. <Ref. to
FU(H4SO)-47,
Engine Control
Module (ECM).>
Replace the sub Go to step 5.
fan relay and
ECM. <Ref. to
FU(H4SO)-47,
Engine Control
Module (ECM).>
Repair poor con- Replace the ECM.
tact in ECM con- <Ref. to
nector. FU(H4SO)-47,
Engine Control
Module (ECM).>
No