
EN(H4SO)-178
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK FUEL TANK CORD.
1) Disconnect the connector from fuel sub
level sensor.
2) Measure the resistance between fuel level
sensor and fuel sub level sensor.
Connector & terminal
(R58) No. 3 — (R59) No. 2:Is the resistance less than 10
Ω?Go to step 8.Repair open circuit
between fuel level
sensor and fuel
sub level sensor.
8 CHECK FUEL TANK CORD.
Measure the resistance between fuel level sen-
sor and coupler connector.
Connector & terminal
(R57) No. 2 — (R59) No. 1:Is the resistance less than 10
Ω?Go to step 9.Repair open circuit
between coupling
connector and fuel
level sensor.
9 CHECK FUEL LEVEL SENSOR.
1) Remove the fuel pump assembly.
2) While moving the fuel level sensor float up
and down, measure resistance between fuel
level sensor terminals.
Te r m i n a l s
No. 3 — No. 5:Is the resistance more than
54.5 Ω?Replace the fuel
level sensor.
Fuel Level Sen-
sor.>Go to step 10.
10 CHECK FUEL SUB LEVEL SENSOR.
1) Remove the fuel sub level sensor.
2) While moving the fuel sub level sensor float
up and down, measure resistance between
fuel sub level sensor terminals.
Te r m i n a l s
No. 1 — No. 2:Is the resistance more than
41.5 Ω?Replace the fuel
sub level sensor.
Fuel Sub Level
Sensor.>Replace the com-
bination meter.
Meter Assembly.> Step Check Yes No

EN(H4SO)-190
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Inspect the DTC
using “List of Diag-
nostic Trouble
Code (DTC)”.
of Diagnostic Trou-
ble Code (DTC).>
N
OTE:
In this case, it is not
necessary to in-
spect DTC P0507.Go to step 2.
2 CHECK AIR INTAKE SYSTEM.
1) Turn the ignition switch to ON.
2) Start and idle the engine.
3) Check the following items:
Loose installation of intake manifold, idle air
control solenoid valve and throttle body
Cracks of intake manifold gasket, idle air
control solenoid valve gasket and throttle body
gasket
Disconnections of vacuum hosesIs there any fault in air intake
system?Repair air suction
and leaks.Go to step 3.
3 CHECK THROTTLE CABLE.Is the free play of throttle cable
appropriate?Go to step 4.Adjust throttle
cable.
INSTALLATION,
Accelerator Con-
trol Cable.>
4 CHECK AIR BY-PASS LINE.
1) Turn the ignition switch to OFF.
2) Remove the idle air control solenoid valve
from the throttle body.
3) Confirm that there are no foreign particles
in air by-pass line.Are foreign particles in air by-
pass line?Remove foreign
particles from air
by-pass line.Replace the idle
air control solenoid
valve.
INSTALLATION,
Idle Air Control
Solenoid Valve.>

EN(H4SO)-195
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Inspect DTC using
“List of Diagnostic
Trouble Code
(DTC)”.
of Diagnostic Trou-
ble Code (DTC).>
N
OTE:
In this case, it is not
necessary to in-
spect DTC P0519.Go to step 2.
2 CHECK AIR INTAKE SYSTEM.
1) Turn the ignition switch to ON.
2) Start the engine, and idle it.
3) Check the following items:
Loose installation of intake manifold, idle air
control solenoid valve and throttle body
Cracks of intake manifold gasket, idle air
control solenoid valve gasket and throttle body
gasket
Disconnections of vacuum hosesIs there any fault in air intake
system?Repair air suction
and leaks.Go to step 3.
3 CHECK THROTTLE CABLE.Is the free play of throttle cable
appropriate?Go to step 4.Adjust throttle
cable.
INSTALLATION,
Accelerator Con-
trol Cable.>
4 CHECK AIR BY-PASS LINE.
1) Turn the ignition switch to OFF.
2) Remove the idle air control solenoid valve
from the throttle body.
3) Confirm that there are no foreign particles
in air by-pass line.Are foreign particles in air by-
pass line?Remove foreign
particles from air
by-pass line.Replace the idle
air control solenoid
valve.
Air Control Sole-
noid Valve.>

EN(H4SO)-197
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN TCM AND
CRUISE CONTROL UNIT CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from TCM and
cruise control unit.
3) Measure the resistance of harness
between TCM and cruise control unit connec-
tor.
Connector & terminal
(B55) No. 22 — (B94) No. 3:Is the resistance less than 1
Ω?Go to step 2.Repair open circuit
in harness
between cruise
control unit and
TCM connector.
2 CHECK HARNESS BETWEEN TCM AND
CRUISE CONTROL UNIT CONNECTOR.
Measure the resistance of harness between
TCM and chassis ground.
Connector & terminal
(B55) No. 22 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair the short
circuit of harness
between TCM and
cruise control unit
connector.
3 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM and cruise
control unit.
2) Lift up the vehicle or set it to the free roller.
CAUTION:
For AWD model, all wheels up from floor.
3) Start the engine.
4) Turn the cruise control main switch to ON.
5) Shift the select lever to “D” range and
slowly increase the vehicle speed to 50 km/h
(31 MPH).
6) Turn the cruise control command switch to
ON.
7) Measure the voltage between TCM and
chassis ground.
Connector & terminal
(B55) No. 22 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 4.Check cruise con-
trol command
switch circuit.
Cruise Control
Command
Switch.>
4 CHECK POOR CONTACT.
Check poor contact in TCM connector. Is there poor contact in TCM
connector?Repair poor con-
tact in TCM con-
nector.Replace the TCM.
trol Module
(TCM).>

EN(H4SO)-202
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Connect the test mode connector at the
lower portion of instrument panel (on the
driver’s side).
3) Turn the ignition switch to ON.
4) While operating the radiator fan relay, mea-
sure the voltage between ECM and chassis
ground.
N
OTE:
Radiator fan relay operation can be executed
using Subaru Select Monitor. For procedure,
refer to “Compulsory Valve Operation Check
Mode”.
Connector & terminal
(B134) No. 14 (+) — Chassis ground (
−):Is the voltage 0 — 10 V? Repair the poor
contact in ECM
connector.Go to step 2.
2 CHECK GROUND SHORT CIRCUIT IN RADI-
ATOR MAIN FAN RELAY CONTROL CIR-
CUIT.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM connector and chassis ground.
Connector & terminal
(B134) No. 14 — Chassis ground:Is the resistance less than 10
Ω?Repair the ground
short circuit in
radiator main fan
relay control cir-
cuit.Go to step 3.
3 CHECK POWER SUPPLY FOR RELAY.
1) Remove the main fan relay from A/C relay
holder.
2) Turn the ignition switch to ON.
3) Measure the voltage between fuse and
relay box (F/B) connector and chassis ground.
Connector & terminal
(F27) No. 34 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 4.Repair open circuit
in harness
between ignition
switch and fuse
and relay box (F/B)
connector.
4 CHECK MAIN FAN RELAY.
1) Turn the ignition switch to OFF.
2) Measure the resistance between main fan
relay terminals.
Te r m i n a l s
No. 32 — No. 34:Is the resistance 87 — 107 Ω? Go to step 5.Replace the main
fan relay.
5 CHECK OPEN CIRCUIT IN MAIN FAN RE-
LAY CONTROL CIRCUIT.
Measure the resistance of harness between
ECM and main fan relay connector.
Connector & terminal
(B134) No. 14 — (F27) No. 32:Is the resistance less than 1
Ω?Go to step 6.Repair harness
and connector.
NOTE:
In this case repair
the following:
Open circuit in
harness between
ECM and main fan
relay connector
Poor contact in
coupling connector
6 CHECK POOR CONTACT.
Check poor contact in ECM or main fan relay
connector. Is there poor contact in ECM or
main fan relay connector?Repair the poor
contact in ECM or
main fan relay con-
nector.Contact the SUB-
ARU dealer.

EN(H4SO)-205
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OUTPUT SIGNAL FROM ECM.
1) Turn the ignition switch to OFF.
2) Connect the test mode connector at the
lower portion of instrument panel (on the
driver’s side).
3) Turn the ignition switch to ON.
4) While operating the radiator fan relay, mea-
sure the voltage between ECM and chassis
ground.
N
OTE:
Radiator fan relay operation can be executed
using Subaru Select Monitor. For procedure,
refer to “Compulsory Valve Operation Check
Mode”.
Connector & terminal
(B134) No. 14 (+) — Chassis ground (
−):
(B134) No. 13 (+) — Chassis ground (
−):Is the voltage 0 — 10 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. In this
case, repair poor
contact in ECM
connector.Go to step 2.
2 CHECK SHORT CIRCUIT IN RADIATOR FAN
RELAY CONTROL CIRCUIT.
1) Turn the ignition switch to OFF.
2) Remove the main fan relay and sub fan
relay. (model with A/C)
3) Disconnect the test mode connectors
4) Turn the ignition switch to ON.
5) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 14 (+) — Chassis ground (
−):
(B134) No. 13 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in
radiator fan relay
control circuit.
After repair,
replace the ECM.
Engine Control
Module (ECM).>Go to step 3.
3 CHECK MAIN FAN RELAY.
1) Turn the ignition switch to OFF.
2) Remove the main fan relay.
3) Measure the resistance between main fan
relay terminals.
Te r m i n a l s
No. 30 — No. 31:Is the resistance less than 1
Ω?Replace the main
fan relay and
ECM.
Engine Control
Module (ECM).>Go to step 4.
4 CHECK SUB FAN RELAY.
1) Remove the sub fan relay.
2) Measure the resistance between sub fan
relay terminals.
Te r m i n a l s
No. 28 — No. 29:Is the resistance less than 1
Ω?Replace the sub
fan relay and
ECM.
Engine Control
Module (ECM).>Go to step 5.
5 CHECK POOR CONTACT.
Check poor contact in ECM connector.Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Replace the ECM.
Engine Control
Module (ECM).>

EN(H4SO)-207
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK OPERATION OF BRAKE LIGHT.Does the brake light come on
when depressing the brake
pedal?Go to step 2.Repair or replace
the brake light cir-
cuit.
2 CHECK HARNESS BETWEEN TCM AND
BRAKE LIGHT SWITCH CONNECTOR.
1) Disconnect the connectors from TCM and
brake light switch.
2) Measure the resistance of harness
between TCM and brake light switch connec-
tor.
Connector & terminal
WITHOUT CRUISE CONTROL
(B55) No. 12 — (B64) No. 2:
WITH CRUISE CONTROL
(B55) No. 12 — (B65) No. 3:Is the resistance less than 1
Ω?Go to step 3.Repair or replace
the harness and
connector.
N
OTE:
In this case repair
the following:
Open circuit in
harness between
TCM and brake
light switch con-
nector
Poor contact in
TCM connector
Poor contact in
brake light switch
connector
3 CHECK HARNESS BETWEEN TCM AND
BRAKE LIGHT SWITCH CONNECTOR.
Measure the resistance of harness between
TCM and chassis ground.
Connector & terminal
(B55) No. 12 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 4.Repair ground
short circuit in har-
ness between
TCM and brake
light switch con-
nector.
4 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM and brake
light switch.
2) Measure the voltage between TCM and
chassis ground.
Connector & terminal
(B55) No. 12 (+) — Chassis ground (
−):Is the voltage less than 1 V
when releasing the brake
pedal?Go to step 5.Adjust or replace
the brake light
switch.
SWITCH,
INSPECTION,
Stop Light Sys-
tem.>
5 CHECK INPUT SIGNAL FOR TCM.
Measure the voltage between TCM and chas-
sis ground.
Connector & terminal
(B55) No. 12 (+) — Chassis ground (
−):Is the voltage more than 10 V
when depressing the brake
pedal?Go to step 6.Adjust or replace
the brake light
switch.
SWITCH,
INSPECTION,
Stop Light Sys-
tem.>
6 CHECK POOR CONTACT.
Check poor contact in TCM connector.Is there poor contact in TCM
connector?Repair poor con-
tact in TCM con-
nector.Replace the TCM.
trol Module
(TCM).>

EN(H4SO)-213
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Is DTC P0705 displayed? Inspect the DTC
using “List of Diag-
nostic Trouble
Code (DTC)”.
of Diagnostic Trou-
ble Code (DTC).>Go to step 2.
2 CHECK INPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Shift the select lever to other than “N” and
“P” ranges.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 21 (+) — Chassis ground (
−):Is the voltage more than 10 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
TRANSMISSION HARNESS CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
transmission harness connector (T3).
3) Measure the resistance of harness
between ECM connector and chassis ground.
Connector & terminal
(B136) No. 21 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 4.Repair ground
short circuit in har-
ness between
ECM and trans-
mission harness
connector.
4 CHECK TRANSMISSION HARNESS CON-
NECTOR.
1) Disconnect the connector from inhibitor
switch.
2) Measure the resistance of harness
between transmission harness connector and
engine ground.
Connector & terminal
(T3) No. 12 — Engine ground:Is the resistance more than 1
MΩ?Go to step 5.Repair ground
short circuit in har-
ness between
transmission har-
ness and inhibitor
switch connector.
5 CHECK INHIBITOR SWITCH.
Measure the resistance between inhibitor
switch connector receptacle’s terminals with
select lever at other than “N” and “P” range.
Te r m i n a l s
No. 7 — No. 12:Is the resistance more than 1
MΩ?Go to step 6.Replace inhibitor
switch.
Switch.>
6 CHECK SELECTOR CABLE CONNECTION.Is there any fault in selector
cable connection to inhibitor
switch?Repair the select
cable connection.
Select Cable.>Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.