2004 SUBARU FORESTER ignition

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”. 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.
FU(H4SO)-44,
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. FU(H4SO)-44,
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. FU(H4SO)-44,
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.
FU(H4SO)-44,
Engine Control
Module (ECM).>

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)”.
EN(H4SO)-72, List
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. 4AT-51, Inhibitor
Switch.>
6 CHECK SELECTOR CABLE CONNECTION.Is there any fault in selector
cable connection to inhibitor
switch?Repair the select
cable connection.
INSPECTION,
Select Cable.>Contact the SUB-
ARU dealer.
N
OTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.

EN(H4SO)-215
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK INPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Place the shift lever in neutral.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 21 (+) — Chassis ground (
−):Is the voltage more than 10 V? Go to step 2.Go to step 4.
2 CHECK INPUT SIGNAL FROM ECM.
1) Place the shift lever except in neutral.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 21 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 3.Go to step 4.
3 CHECK POOR CONTACT.
Check poor contact in ECM connector.Is there poor contact in ECM
connector?Repair the poor
contact in ECM
connector.Contact the SUB-
ARU dealer.
4 CHECK NEUTRAL POSITION SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from transmis-
sion harness.
3) Place the shift lever in neutral.
4) Measure the resistance between transmis-
sion harness and connector terminals.
Connector & terminal
(T2) No. 1 — No. 2:Is the resistance more than 1
MΩ?Go to step 5.Repair short circuit
in transmission
harness or replace
the neutral position
switch.
5 CHECK NEUTRAL POSITION SWITCH.
1) Place the shift lever except in neutral.
2) Measure the resistance between transmis-
sion harness connector terminals.Is the resistance less than 1
Ω?Go to step 6.Repair short circuit
in transmission
harness or replace
the neutral position
switch.
6 CHECK HARNESS BETWEEN ECM AND
NEUTRAL POSITION SWITCH CONNEC-
TOR.
Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B136) No. 21 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 7.Repair ground
short circuit in har-
ness between
ECM and trans-
mission harness
connector.
7 CHECK HARNESS BETWEEN ECM AND
NEUTRAL POSITION SWITCH CONNEC-
TOR.
1) Disconnect the connector from ECM.
2) Measure the resistance of harness
between ECM and transmission harness con-
nector.
Connector & terminal
LHD MODEL
(B136) No. 21 — (B25) No. 1:
RHD MODEL
(B136) No. 21 — (B25) No. 2:Is the resistance less than 1
Ω?Go to step 8.Repair open circuit
in harness
between ECM and
transmission har-
ness connector.

EN(H4SO)-218
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)”.
EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>Go to step 2.
2 CHECK INPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground with select lever at “N” and “P”
ranges.
Connector & terminal
(B136) No. 21 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 3.Go to step 5.
3 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground with select lever at except “N” and
“P” ranges.
Connector & terminal
(B136) No. 21 (+) — Chassis ground (
−):Is the voltage between 4.5 —
5.5 V?Go to step 4.Go to step 5.
4 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.
FU(H4SO)-44,
Engine Control
Module (ECM).>
5 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B136) No. 21 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair the battery
short circuit in har-
ness between
ECM and inhibitor
switch connector.Go to step 6.
6 CHECK HARNESS BETWEEN ECM AND IN-
HIBITOR SWITCH CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM and
inhibitor switch.
3) Measure the resistance of harness
between ECM and inhibitor switch connector.
Connector & terminal
(B136) No. 21 — (T7) No. 12:Is the resistance less than 1
Ω?Go to step 7.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and inhibitor
switch connector.
 Poor contact in
coupling connector
 Poor contact in
inhibitor switch
connector
 Poor contact in
ECM connector.
7 CHECK INHIBITOR SWITCH GROUND LINE.
Measure the resistance of harness between
inhibitor switch connector and engine ground.
Connector & terminal
(T7) No. 7 — Engine ground:Is the resistance less than 5
Ω?Go to step 8.Repair open circuit
in harness
between inhibitor
switch connector
and ground line.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
inhibitor switch
connector and
ground line

EN(H4SO)-223
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 2.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.
N
OTE:
In this case repair
the following:
 Poor contact in
ECM connector.
 Poor contact in
TCM connector
2 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
TCM.
3) Measure the resistance of harness
between ECM and chassis ground.
Connector & terminal
(B134) No. 10 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair ground
short circuit in har-
ness between
ECM and TCM
connector.
3 CHECK OUTPUT SIGNAL FROM ECM.
1) Connect the connector to ECM.
2) Turn the ignition switch to ON.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage more than 5 V? Go to step 4.Repair the poor
contact in ECM
connector.
4 CHECK DTC FOR AUTOMATIC TRANSMIS-
SION.
Read DTC for automatic transmission. 4AT(H4SO)-20, Read Diagnostic Trouble Code
(DTC).>Does the DTC appear for auto-
matic transmission?Check the DTC for
automatic trans-
mission. 4AT(H4SO)-36,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).>Replace the TCM.
Transmission Con-
trol Module
(TCM).>

EN(H4SO)-225
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and TCM
connector.Go to step 2.
2 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage more than 4 V? Go to step 5.Go to step 3.
3 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage less than 1 V? Repair the poor
contact in ECM
connector.Go to step 4.
4 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B134) No. 10 (+) — Chassis ground (
−):Is the voltage 1 — 4 V? Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.
N
OTE:
In this case repair
the following:
 Poor contact in
ECM connector.
 Poor contact in
TCM connectorContact the SUB-
ARU dealer.
NOTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.
5 CHECK HARNESS BETWEEN ECM AND
TCM CONNECTOR.
Measure the voltage between TCM and chas-
sis ground.
Connector & terminal
(B55) No. 17 (+) — Chassis ground (
−):Is the voltage more than 4 V? Go to step 6.Repair the open
circuit in harness
between ECM and
TCM connector.
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.Check TCM power
supply line and
grounding line.

EN(H4SO)-230
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)”.
EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>Go to step 2.
2 CHECK FRONT (A/F) OXYGEN SENSOR DA-
TA.
1) Start the engine.
2) While observing the Subaru Select Monitor
or OBD-II general scan tool screen, warm-up
the engine until coolant temperature is above
70°C (160°F).
If the engine is already warmed-up, operate at
idle speed for at least 1 minute.
3) Read the data of front oxygen (A/F) sensor
signal at idling using Subaru Select Monitor or
OBD-II general scan tool.
NOTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the voltage 0.85 — 1.15 V? Go to step 3.Go to step 4.
3 CHECK FRONT (A/F) OXYGEN SENSOR DA-
TA.
Race the engine at speeds from idling to 5,000
rpm for a total of 5 cycles.
N
OTE:
 Normally the air fuel ratio be rich at racing.
 To increase engine speed to 5,000 rpm,
slowly depress accelerator pedal, taking
approximately 5 seconds, and quickly release
accelerator pedal to decrease engine speed.Is the voltage more than 1.1 V? Go to step 6.Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
front oxygen (A/F) sensor connector.
3) Measure the resistance between ECM and
front oxygen (A/F) sensor.
Connector & terminal
(B136) No. 13 — (B18) No. 1:
(B136) No. 22 — (B18) No. 2:Is the resistance less than 5
Ω?Go to step 5.Repair open circuit
between ECM and
front oxygen (A/F)
sensor.
5 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B136) No. 13 — Chassis ground:
(B136) No. 22 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 6.Repair ground
short circuit
between ECM and
front oxygen (A/F)
sensor.

EN(H4SO)-234
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK POWER SUPPLY TO EGR VALVE.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from EGR valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between EGR valve
connector and engine ground.
Connector & terminal
(E18) No. 2 (+) — Engine ground (
−):
(E18) No. 5 (+) — Engine ground (
−):Is the voltage more than 10 V? Go to step 2.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
EGR valve and
main relay connec-
tor
 Poor contact in
coupling connector
2 CHECK HARNESS BETWEEN ECM AND
EGR VALVE CONNECTOR.
1) Turn the ignition switch to OFF.
2) Measure the voltage between ECM and
EGR valve connector.
Connector & terminal
DTC P1492; (B134) No. 18 — (E18) No. 6:
DTC P1494; (B134) No. 17 — (E18) No. 1:
DTC P1496; (B134) No. 16 — (E18) No. 4:
DTC P1498; (B134) No. 15 — (E18) No. 3:Is the resistance less than 1
Ω?Go to step 3.Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and EGR
valve connector.
 Poor contact in
coupling connector
3 CHECK HARNESS BETWEEN ECM AND
EGR VALVE CONNECTOR.
1) Disconnect the connector from ECM.
2) Measure the resistance between ECM con-
nector and chassis ground.
Connector & terminal
DTC P1492; (B134) No. 18 — Chassis
ground:
DTC P1494; (B134) No. 17 — Chassis
ground:
DTC P1496; (B134) No. 16 — Chassis
ground:
DTC P1498; (B134) No. 15 — Chassis
ground:Is the resistance more than 1
MΩ?Go to step 4.Repair ground
short in harness
between ECM and
EGR valve con-
nector.
4 CHECK POOR CONTACT.
Check poor contact in ECM connector and
EGR valve connector.Is there poor contact in ECM
connector or EGR valve con-
nector?Repair poor con-
tact in ECM con-
nector or EGR
valve connector.Replace the EGR
valve. FU(H4SO)-34,
EGR Valve.>