Subaru IMPREZA 2004 Service Manual page 69

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK ANY OTHER DTC ON DISPLAY.
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 (B134) No. 34 (+) — Chassis
ground ( − − − − ):
#2 (B134) No. 23 (+) — Chassis
ground ( − − − − ):
#3 (B134) No. 22 (+) — Chassis
ground ( − − − − ):
#4 (B134) No. 8 (+) — 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)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 (B134) No. 34 — (E5) No. 1:
#2 (B134) No. 23 — (E16) No. 1:
#3 (B134) No. 22 — (E6) No. 1:
#4 (B134) No. 8 — (E17) No. 1:
5 CHECK FUEL INJECTOR.
Measure the resistance between fuel injector
terminals on faulty cylinder.
Terminals
No. 1 — No. 2:
Check
Is any other DTC displayed?
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 Ω — 20 Ω? Go to step 6.
EN(H4SO)(diag)-146
Yes
Check DTC using Go to step 2.
"List of Diagnostic
Trouble Code
(DTC)". <Ref. to
EN(H4SO)(diag)-
74, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0301, P0302,
P0303 and P0304.
Go to step 3.
Go to step 4. Repair ground
short circuit in har-
ness between fuel
injector and ECM
connector.
Go to step 5. Repair harness
and connector.
NOTE:
In this case, repair
the following:
• Open circuit in
harness between
ECM and fuel
injector connector
• Poor contact in
coupling connector
Replace the faulty
fuel injector. <Ref.
to FU(H4SO)-38,
Fuel Injector.>
No