Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 265

EN(H4DOTC)(diag)-284

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

10

CHECK OUTPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground on faulty cylinders.

Connector & terminal

#1 (B134) No. 10 (+) — Chassis ground (–):
#2 (B134) No. 11 (+) — Chassis ground (–):
#3 (B134) No. 12 (+) — Chassis ground (–):
#4 (B134) No. 13 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step

15.

Go to step

11.

11

CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel injector
on faulty cylinders.
3) Measure the resistance between fuel injec-
tor connector and engine ground on faulty cylin-
ders.

Connector & terminal

#1 (E5) No. 2 — Engine ground:
#2 (E16) No. 2 — Engine ground:
#3 (E6) No. 2 — Engine ground:
#4 (E17) No. 2 — Engine ground:

Is the resistance 1 MΩ or
more?

Go to step

12.

Repair the short
circuit to ground in
harness between
ECM connector
and fuel injector
connector.

12

CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
Measure the resistance of harness between
ECM and fuel injector connector on faulty cylin-
ders.

Connector & terminal

#1 (B134) No. 10 — (E5) No. 2:
#2 (B134) No. 11 — (E16) No. 2:
#3 (B134) No. 12 — (E6) No. 2:
#4 (B134) No. 13 — (E17) No. 2:

Is the resistance less than 1 Ω? Go to step

13.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit in
harness between
ECM

connector

and fuel injector
connector
• Poor contact of
coupling connector

13

CHECK FUEL INJECTOR.
Measure the resistance between fuel injector
terminals on faulty cylinder.

Terminals

No. 1 — No. 2:

Is the resistance 5 — 20 Ω?

Go to step

14.

Replace the faulty
fuel injector. <Ref.
to FU(STI)-45,
Fuel Injector.>
<Ref. to FU(w/o
STI)-45, Fuel
Injector.>

14

CHECK POWER SUPPLY LINE.
1) Turn the ignition switch to ON.
2) Measure the voltage between fuel injector
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 (–):

Is the voltage 10 V or more?

Repair the poor
contact of all con-
nectors in fuel
injector circuit.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit in
harness between
the main relay con-
nector and fuel in-
jector connector on
faulty cylinders
• Poor contact of
coupling connector
• Poor contact of
main relay connec-
tor

Step

Check

Yes

No

EN(H4DOTC)(diag)-285

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

15

CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from fuel injector
on faulty cylinders.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground on faulty cylinders.

Connector & terminal

#1 (B134) No. 10 (+) — Chassis ground (–):
#2 (B134) No. 11 (+) — Chassis ground (–):
#3 (B134) No. 12 (+) — Chassis ground (–):
#4 (B134) No. 13 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the short
circuit to power in
harness between
ECM connector
and fuel injector
connectors.

Go to step

16.

16

CHECK FUEL INJECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between fuel injec-
tor terminals on faulty cylinder.

Terminals

No. 1 — No. 2:

Is the resistance 5 — 20 Ω?

Go to step

17.

Replace the faulty
fuel injector. <Ref.
to FU(STI)-45,
Fuel Injector.>
<Ref. to FU(w/o
STI)-45, Fuel
Injector.>

17

CHECK INSTALLATION OF CAMSHAFT PO-
SITION SENSOR/CRANKSHAFT POSITION
SENSOR.

Is the camshaft position sensor
or crankshaft position sensor
loosely installed?

Tighten the cam-
shaft position sen-
sor or crankshaft
position sensor.
<Ref. to FU(STI)-
37, Camshaft Posi-
tion Sensor.>
<Ref. to FU(STI)-
35, Crankshaft
Position Sensor.>
<Ref. to FU(w/o
STI)-37, Camshaft
Position Sensor.>
<Ref. to FU(w/o
STI)-35, Crank-
shaft Position Sen-
sor.>

Go to step

18.

18

CHECK CRANK SPROCKET.
Remove the timing belt cover. <Ref. to ME(STI)-
49, REMOVAL, Timing Belt Cover.> <Ref. to
ME(w/o STI)-47, REMOVAL, Timing Belt
Cover.>

Is the crank sprocket rusted or
does it have broken teeth?

Replace the crank
sprocket. <Ref. to
ME(STI)-60, Crank
Sprocket.> <Ref. to
ME(w/o STI)-58,
Crank Sprocket.>

Go to step

19.

19

CHECK INSTALLATION CONDITION OF
TIMING BELT.
Turn the crankshaft, and align alignment mark
on crank sprocket with alignment mark on cylin-
der block.
ST 499987500

CRANKSHAFT
SOCKET

Is the timing belt dislocated
from its proper position?

Repair the installa-
tion condition of
timing belt. <Ref.
to ME(STI)-50,
Timing Belt.> <Ref.
to ME(w/o STI)-48,
Timing Belt.>

Go to step

20.

20

CHECK ELECTRONIC THROTTLE CON-
TROL RELAY.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control relay.
3) Connect the battery to terminals No. 31 and
No. 32 of electronic throttle control relay.
4) Measure the resistance between electronic
throttle control relay terminals.

Terminals

No. 29 — No. 30:

Is the resistance less than 1 Ω? Go to step

21.

Replace the elec-
tronic throttle con-
trol relay. <Ref. to
FU(STI)-64, Elec-
tronic Throttle
Control Relay.>
<Ref. to FU(w/o
STI)-62, Elec-
tronic Throttle
Control Relay.>

Step

Check

Yes

No

EN(H4DOTC)(diag)-286

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

21

CHECK POWER SUPPLY OF ELECTRONIC
THROTTLE CONTROL RELAY.
Measure the voltage between electronic throttle
control relay connector and chassis ground.

Connector & terminal

(B220) No. 29 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step

22.

Repair the open or
ground short circuit
of power supply
circuit.

22

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Disconnect the connector from ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between electronic
throttle control relay connector and chassis
ground.

Connector & terminal

(B220) No. 32 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.

Go to step

23.

23

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between electronic
throttle control relay connector and chassis
ground.

Connector & terminal

(B220) No. 32 — Chassis ground:
(B220) No. 30 — Chassis ground:

Is the resistance 1 MΩ or
more?

Go to step

24.

Repair the short
circuit to ground in
harness between
ECM connector
and electronic
throttle control
relay connector.

24

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL RE-
LAY CONNECTOR.
Measure the resistance between ECM connec-
tor and electronic throttle control relay connec-
tor.

Connector & terminal

(B135) No. 17 — (B220) No. 32:
(B135) No. 7 — (B220) No. 30:

Is the resistance less than 1 Ω? Go to step

25.

Repair the open
circuit in harness
between ECM con-
nector and elec-
tronic throttle
control relay con-
nector.

25

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
electronic throttle control.
3) Measure the resistance between ECM con-
nector and chassis ground.

Connector & terminal

(B134) No. 19 — Chassis ground:
(B134) No. 18 — Chassis ground:
(B134) No. 18 — (B136) No. 4:
(B134) No. 28 — Chassis ground:

Is the resistance 1 MΩ or
more?

Go to step

26.

Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.

Step

Check

Yes

No

EN(H4DOTC)(diag)-287

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

26

CHECK SHORT CIRCUIT INSIDE THE ECM.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.

Connector & terminal

(B57) No. 6 — Engine ground:
(B57) No. 4 — Engine ground:

Is the resistance 1 MΩ or
more?

Go to step

27.

Repair the ground
short circuit of har-
ness between
ECM connector
and electronic
throttle control
connector.
Replace the ECM if
defective. <Ref. to
FU(STI)-59,
Engine Control
Module (ECM).>
<Ref. to FU(w/o
STI)-57, Engine
Control Module
(ECM).>

27

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness between
ECM connector and electronic throttle control
connector.

Connector & terminal

(B134) No. 18 — (E57) No. 6:
(B134) No. 28 — (E57) No. 4:
(B134) No. 29 — (E57) No. 3:

Is the resistance less than 1 Ω? Go to step

28.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit in
harness between
ECM

connector

and

electronic

throttle

control

connector
• Poor contact of
coupling connector

28

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Connect the connector to ECM.
2) Measure the resistance between electronic
throttle control connector and engine ground.

Connector & terminal

(E57) No. 3 — Engine ground:

Is the resistance less than 5 Ω? Go to step

29.

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit of
harness between
ECM

connector

and engine ground
• Poor contact of
ECM connector
• Poor contact of
coupling connector

29

CHECK HARNESS BETWEEN ECM AND
ELECTRONIC THROTTLE CONTROL CON-
NECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between electronic
throttle control connector and engine ground.

Connector & terminal

(E57) No. 6 (+) — Engine ground (–):
(E57) No. 4 (+) — Engine ground (–):

Is the voltage 5 V or more?

Repair the short
circuit to power in
the harness
between ECM con-
nector and elec-
tronic throttle
control connector.

Go to step

30.

Step

Check

Yes

No