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Subaru Legacy IV (2008 year). Manual - part 581

EN(H6DO)(diag)-297

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CHECK AIR INTAKE SYSTEM.

Are there holes, loose bolts or
disconnection of hose on air
intake system?

Repair the air
intake system.

Go to step 5.

CHECK FUEL PRESSURE.

WARNING:
Place “NO OPEN FLAMES” signs near the
working area.

CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to
ME(H6DO)-27, INSPECTION, Fuel Pressure.>

CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.

Is the measured value 333 —
363 kPa (3.4 — 3.7 kgf/cm

48 — 53 psi)?

Go to step 6.

Repair the follow-
ing item.
Fuel pressure is
too high:
• Clogged fuel line
or bent hose
Fuel pressure is
too low:
• Improper fuel
pump discharge
• Clogged fuel line

CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm up completely.
2) Read the data of engine coolant tempera-
ture sensor signal using Subaru Select Monitor
or general scan tool.

NOTE:
• SUBARU SELECT MONITOR
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”. <Ref.
to EN(H6DO)(diag)-34, Subaru Select Moni-
tor.>
• General Scan Tool
For detailed operation procedures, refer to the
general scan tool operation manual.

Is the engine coolant tempera-
ture 75°C (167°F) or higher?

Go to step 7.

Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H6DO)-20,
Engine Coolant
Temperature Sen-
sor.>

CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) Place the select lever in “P” range or “N”
range.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Read the data of the mass air flow and
intake air temperature sensor signal using Sub-
aru Select Monitor or general scan tool.

Is the measured value 2.0 —
5.0 g/s (0.26 — 0.66 lb/m)?

Go to step 8.

Replace the mass
air flow and intake
air temperature
sensor. <Ref. to
FU(H6DO)-26,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>

Step

Check

Yes

EN(H6DO)(diag)-298

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CHECK MASS AIR FLOW AND INTAKE AIR
TEMPERATURE SENSOR.
1) Start the engine and warm up engine until
coolant temperature is higher than 75°C
(167°F).
2) Place the select lever in “P” range or “N”
range.
3) Turn the A/C switch to OFF.
4) Turn all the accessory switches to OFF.
5) Open the front hood.
6) Measure the ambient temperature.
7) Read the data of the mass air flow and
intake air temperature sensor signal using Sub-
aru Select Monitor or general scan tool.

Subtract ambient temperature
from intake air temperature. Is
the obtained value –10 — 50°C
(–18 — 90°F)?

Go to step 9.

Check the mass air
flow and intake air
temperature sen-
sor. <Ref. to
FU(H6DO)-26,
Mass Air Flow and
Intake Air Temper-
ature Sensor.>

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 (B137) No. 8 (+) — Chassis ground (–):
#2 (B137) No. 9 (+) — Chassis ground (–):
#3 (B137) No. 10 (+) — Chassis ground (–):
#4 (B137) No. 11 (+) — Chassis ground (–):
#5 (B137) No. 12 (+) — Chassis ground (–):
#6 (B137) No. 13 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 14.

Go to step 10.

CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR.
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. 1 — Engine ground:
#2 (E16) No. 1 — Engine ground:
#3 (E6) No. 1 — Engine ground:
#4 (E17) No. 1 — Engine ground:
#5 (E43) No. 1 — Engine ground:
#6 (E44) No. 1 — Engine ground:

Is the resistance 1 M

: or

more?

Go to step 11.

Repair the ground
short circuit of har-
ness between
ECM and fuel
injector.

CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR.
Measure the resistance of harness between
ECM and fuel injector on faulty cylinders.

Connector & terminal

#1 (B137) No. 8 — (E5) No. 1:
#2 (B137) No. 9 — (E16) No. 1:
#3 (B137) No. 10 — (E6) No. 1:
#4 (B137) No. 11 — (E17) No. 1:
#5 (B137) No. 12 — (E43) No. 1:
#6 (B137) No. 13 — (E44) No. 1:

Is the resistance less than 1

:? Go to step 12.

Repair the harness
and connector.

NOTE:
In this case, repair
the following item:
• Open circuit of
harness between
ECM and fuel in-
jector connector
• Poor contact of
coupling connector

Step

Check

Yes

EN(H6DO)(diag)-299

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

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

Terminals

No. 1 — No. 2:

Is the resistance between 5 —
20

Go to step 13.

Replace the faulty
fuel injector. <Ref.
to FU(H6DO)-28,
Fuel Injector.>

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. 2 (+) — Engine ground (–):
#2 (E16) No. 2 (+) — Engine ground (–):
#3 (E6) No. 2 (+) — Engine ground (–):
#4 (E17) No. 2 (+) — Engine ground (–):
#5 (E43) No. 2 (+) — Engine ground (–):
#6 (E44) No. 2 (+) — 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 and
fuel injector on
faulty cylinders
• Poor contact of
coupling connector
• Poor contact of
main relay connec-
tor

CHECK HARNESS BETWEEN ECM AND
FUEL INJECTOR.
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

Is the voltage 10 V or more?

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

Go to step 15.

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 less than 1

:? Replace the faulty

fuel injector. <Ref.
to FU(H6DO)-28,
Fuel Injector.>

Go to step 16.

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.

Go to step 17.

CHECK CRANK PLATE.

Is the crank sprocket rusted or
the teeth of crank plate broken?

Replace the crank
plate. <Ref. to
ME(H6DO)-64,
Cylinder Block.>

Go to step 18.

CHECK INSTALLATION CONDITION OF
TIMING CHAIN.
Turn the crankshaft using ST, and align the
alignment mark on crank sprocket with align-
ment mark on cylinder block.
ST

18252AA000

CRANKSHAFT
SOCKET

Is the timing chain dislocated
from its proper position?

Correct the instal-
lation condition of
timing chain. <Ref.
to ME(H6DO)-46,
Timing Chain
Assembly.>

Go to step 19.

Step

Check

Yes

EN(H6DO)(diag)-300

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

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. 5 and
No. 6 of electronic throttle control relay.
4) Measure the resistance between electronic
throttle control relay terminals.

Terminals

No. 7 — No. 8:

Is the resistance less than 1

:? Go to step 20.

Replace the elec-
tronic throttle con-
trol relay. <Ref. to
EN(H6DO)(diag)-
8, Electrical Com-
ponent Location.>

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

Connector & terminal

(B362) No. 7 (+) — Chassis ground (–):

Is the voltage 10 V or more?

Go to step 21.

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

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

Connector & terminal

(B362) No. 6 (+) — Chassis ground (–):

Is the voltage 10 V or more?

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

Go to step 22.

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

Connector & terminal

(B362) No. 6 — Chassis ground:
(B362) No. 8 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 23.

Repair the ground
short circuit of har-
ness between
ECM and elec-
tronic throttle con-
trol relay.

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

Connector & terminal

(B136) No. 21 — (B362) No. 6:
(B136) No. 1 — (B362) No. 8:

Is the resistance less than 1

:? Go to step 24.

Repair the open
circuit of harness
between ECM and
electronic throttle
control relay.

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

Connector & terminal

(B134) No. 19 — Chassis ground:
(B134) No. 18 — Chassis ground:
(B134) No. 18 — (B136) No. 6:
(B134) No. 28 — Chassis ground:

Is the resistance 1 M

: or

more?

Go to step 25.

Repair the short
circuit to ground in
harness between
ECM and elec-
tronic throttle con-
trol connector.

Step

Check

Yes

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