Subaru Impreza 2003 Service Manual page 1339

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
2 CHECK OUTPUT SIGNAL FROM ECM.
1)Turn the ignition switch to ON.
2)Measure the voltage between ECM connec-
tor and chassis ground on faulty cylinders.
Connector & terminal
#1 (B84) No. 1 (+) — Chassis ground
( − − − − ):
#2 (B137) No. 6 (+) — Chassis ground
( − − − − ):
#3 (B137) No. 5 (+) — Chassis ground
( − − − − ):
#4 (B137) No. 4 (+) — Chassis ground
( − − − − ):
3 CHECK HARNESS BETWEEN FUEL INJEC-
TOR AND ECM CONNECTOR.
1)Turn the ignition switch to OFF.
2)Disconnect the connector from fuel injector
on faulty cylinders.
3)Disconnect the connector from ECM.
4)Measure the resistance between ECM con-
nector and engine ground on faulty cylinders.
Connector & terminal
#1 (E5) No. 1 — Engine ground:
#2 (E16) No. 1 — Engine ground:
#3 (E6) No. 1 — Engine ground:
#4 (E17) No. 1 — Engine ground:
4 CHECK HARNESS BETWEEN FUEL INJEC-
TOR AND ECM CONNECTOR.
Measure the resistance of harness connector
between ECM connector and fuel injector on
faulty cylinders.
Connector & terminal
#1 (B84) No. 1 — (E5) No. 1:
#2 (B137) No. 6 — (E16) No. 1:
#3 (B137) No. 5 — (E6) No. 1:
#4 (B137) No. 4 — (E17) No. 1:
5 CHECK FUEL INJECTOR.
Measure the resistance between fuel injector
terminals on faulty cylinder.
Terminals
No. 1 — No. 2:
Check
Is the voltage more than 10 V? Go to step 7.
Is the resistance more than 1
MΩ?
Is the resistance less than 1
Ω?
Is the resistance 5 — 20 Ω?
EN(H4DOTC)-163
ENGINE (DIAGNOSTICS)
Yes
Go to step 3.
Go to step 4. Repair the ground
short circuit in har-
ness between fuel
injector and ECM
connector.
Go to step 5. Repair the har-
ness and connec-
tor.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and fuel
injector connector
• Poor contact in
coupling connector
Go to step 6. Replace the faulty
fuel injector. <Ref.
to FU(H4DOTC)-
37, Fuel Injector.>
No