Subaru Impreza 2003 Service Manual page 1371

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
1 CHECK SPEEDOMETER AND TACHOME-
TER OPERATION IN COMBINATION
METER.
2 CHECK INPUT SIGNAL FOR ECM.
1)Turn the ignition switch to ON. (engine OFF)
2)Measure the voltage between ECM connec-
tor and chassis ground.
Connector & terminal
(B135) No. 25 (+) — Chassis ground ( − − − − ):
3 CHECK INPUT VOLTAGE OF ECM.
1)Turn the ignition switch to OFF.
2)Disconnect the combination meter connector
(i11) and ECM connector.
3)Turn the ignition switch to ON.
4)Measure the voltage of harness between
ECM and chassis ground.
Connector & terminal
(B135) No. 25 (+) — Chassis ground ( − − − − ):
4 CHECK HARNESS BETWEEN ECM AND
FUEL TANK CORD.
1)Turn the ignition switch to OFF.
2)Separate the fuel tank cord connector (R57)
and rear wiring harness connector (R15).
3)Measure the resistance between ECM and
fuel tank cord.
Connector & terminal
(B135) No. 25 — (R15) No. 2:
5 CHECK HARNESS BETWEEN FUEL TANK
CORD AND CHASSIS GROUND.
Measure the resistance between fuel tank cord
and chassis ground.
Connector & terminal
(R15) No. 6 — Chassis ground:
6 CHECK FUEL TANK CORD.
1)Disconnect the connector from fuel level
sensor.
2)Measure the resistance between fuel level
sensor and coupling connector.
Connector & terminal
(R57) No. 6 — (R58) No. 5:
Check
Does the speedometer and
tachometer operate normally?
Is the voltage more than 4.75
V?
Is the voltage more than 4.75
V?
Is the resistance less than 5
Ω?
Is the resistance less than 5
Ω?
Is the resistance less than 10
Ω?
EN(H4DOTC)-195
ENGINE (DIAGNOSTICS)
Yes
Go to step 2. Repair or replace
the combination
meter. <Ref. to
IDI-3, Combina-
tion Meter Sys-
tem.>
Go to step 3. Even if malfunc-
tion indicator light
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time. A
temporary poor
contact of the con-
nector may be the
cause.
NOTE:
In this case, repair
the following:
• Poor contact in
fuel pump connec-
tor
• Poor contact in
coupling connector
Go to step 4. Repair the battery
short circuit
between ECM and
combination meter
connector.
Go to step 5. Repair the open
circuit between
ECM and fuel tank
cord.
Go to step 6. Repair the open
circuit between
fuel tank cord and
chassis ground.
NOTE:
In this case, repair
the following:
Poor contact in
coupling connec-
tors
Go to step 7. Repair the open
circuit between
coupling connector
and fuel level sen-
sor.
No