2004 SUBARU FORESTER check engine light

EN(H4SO)-177
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK SPEEDOMETER AND TACHOME-
TER OPERATION IN COMBINATION
METER.Does the speedometer and
tachometer operate normally?Go to step 2.Repair or replace
the combination
meter. 3, Combination
Meter System.>
2 CHECK INPUT SIGNAL FROM ECM.
1) Turn the ignition switch to ON. (engine
OFF)
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B135) No. 25 (+) — Chassis ground (
−):Is the voltage more than 4.75
V?Go to step 3.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. A tempo-
rary poor contact
of the connector
may be the cause.
N
OTE:
In this case repair
the following:
 Poor contact in
fuel pump connec-
tor
 Poor contact in
coupling connector
3 CHECK INPUT VOLTAGE OF ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the combination meter connec-
tor (i11) and ECM connector.
3) Turn the ignition switch to ON.
4) Measure the voltage of harness between
ECM and chassis ground.
Connector & terminal
(B135) No. 25 (+) — Chassis ground (
−):Is the voltage more than 4.75
V?Go to step 4.Repair battery
short circuit
between ECM and
combination meter
connector.
4 CHECK HARNESS BETWEEN ECM AND
FUEL TANK CORD.
1) Turn the ignition switch to OFF.
2) Separate fuel tank cord connector (R57)
and rear wiring harness connector (R15).
3) Measure the resistance between ECM and
fuel tank cord.
Connector & terminal
(B135) No. 25 — (R15) No. 2:Is the resistance less than 5
Ω?Go to step 5.Repair open circuit
between ECM and
fuel tank cord.
5 CHECK HARNESS BETWEEN FUEL TANK
CORD AND CHASSIS GROUND.
Measure the resistance between fuel tank cord
and chassis ground.
Connector & terminal
(R15) No. 3 — Chassis ground:Is the resistance less than 5
Ω?Go to step 6.Repair open circuit
between fuel tank
cord and chassis
ground.
N
OTE:
In this case repair
the following:
Poor contact in
coupling connec-
tor.
6 CHECK FUEL TANK CORD.
1) Disconnect the connector from fuel level
sensor.
2) Measure the resistance between fuel level
sensor and coupler connector.
Connector & terminal
(R57) No. 3 — (R58) No. 5:Is the resistance less than 10
Ω?Go to step 7.Repair open circuit
between coupling
connector and fuel
level sensor.

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)-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. 8, STOP LIGHT
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. 8, STOP LIGHT
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.
Transmission Con-
trol Module
(TCM).>

EN(H4SO)-210
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BK:DTC P0741 TORQUE CONVERTER CLUTCH CIRCUIT PERFORMANCE OR
STUCK OFF
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
 No lock-up (after engine warm-up)
 No shift or excessive tight corner “braking”
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>Go to step 2.
2 CHECK LOCK-UP DUTY SOLENOID CIR-
CUIT.
Check lock-up duty solenoid circuit. 4AT(H4SO)-74, DTC 77 LOCK-UP DUTY
SOLENOID, Diagnostic Procedure with Diag-
nostic Trouble Code (DTC).>Is there any trouble in lock-up
duty solenoid circuit?Repair or replace
the lock-up duty
solenoid circuit.Go to step 3.
3 CHECK THROTTLE POSITION SENSOR
CIRCUIT.
Check the throttle position sensor circuit. to 4AT(H4SO)-41, DTC 31 THROTTLE POSI-
TION SENSOR, Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>Is there any trouble in throttle
position sensor circuit?Repair or replace
the throttle posi-
tion sensor circuit.Go to step 4.
4 CHECK TORQUE CONVERTER TURBINE
SPEED SENSOR CIRCUIT.
Check torque converter turbine speed sensor
circuit. TORQUE CONVERTER TURBINE SPEED
SENSOR, Diagnostic Procedure with Diagnos-
tic Trouble Code (DTC).>Is there any trouble in torque
converter turbine speed sensor
circuit?Repair or replace
the torque con-
ver ter turbine
speed sensor cir-
cuit.Go to step 5.
5 CHECK ENGINE SPEED INPUT CIRCUIT.
Check engine speed input circuit. 4AT(H4SO)-36, DTC 11 ENGINE SPEED SIG-
NAL, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>Is there any trouble in engine
speed input circuit?Repair or replace
the engine speed
input circuit.Go to step 6.
6 CHECK INHIBITOR SWITCH CIRCUIT.
Check inhibitor switch circuit. 4AT(H4SO)-95, CHECK INHIBITOR SWITCH,
Diagnostic Procedure without Diagnostic Trou-
ble Code (DTC).>Is there any trouble in inhibitor
switch circuit?Repair or replace
the inhibitor switch
circuit.Go to step 7.
7 CHECK BRAKE LIGHT SWITCH CIRCUIT.
Check brake light switch circuit. 4AT(H4SO)-88, CHECK BRAKE SWITCH,
Diagnostic Procedure without Diagnostic Trou-
ble Code (DTC).>Is there any trouble in brake
light switch circuit?Repair or replace
the brake light
switch circuit.Go to step 8.

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)-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.

ME(H4DOTC)-32
MECHANICAL
Idle Speed
3. Idle Speed
A: INSPECTION
1. USING SUBARU SELECT MONITOR
1) Before checking the idle speed, check the fol-
lowing:
(1) Ensure the air cleaner element is free from
clogging, ignition timing is correct, spark plugs
are in good condition, and that the hoses are
connected properly.
(2) Ensure the malfunction indicator light does
not illuminate.
2) Warm-up the engine.
3) Stop the engine, and then turn the ignition switch
to OFF.
4) Insert the cartridge to Subaru Select Monitor.
5) Connect the Subaru Select Monitor to data link
connector.
6) Turn the ignition switch to ON, and Subaru Se-
lect Monitor switch to ON.
7) Select the {2. Each System Check} in Main
Menu.
8) Select the {Engine Control System} in Selection
Menu.
9) Select the {1. Current Data Display & Save} in
Engine Control System Diagnosis.
10) Select the {1.12 Data Display} in Data Display
Menu.
11) Start the engine, and then read the engine idle
speed.
12) Check the idle speed when unloaded. (With
headlights, heater fan, rear defroster, radiator fan,
air conditioning, etc. OFF)
Idle speed [No load and gears in neutral]:
700
±100 rpm
13) Check the idle speed when loaded. (Turn the
air conditioning switch to “ON” and operate the
compressor for at least 1 minute before measure-
ment.)
Idle speed [A/C “ON”, no load and gears in neu-
tral]:
A/C Refrigerant pressure (LOW)
MT: 725
±100 rpm
AT: 750
±100 rpm
A/C Refrigerant pressure (HIGH)
MT: 800
±100 rpm
AT: 825
±100 rpm
NOTE:
As idle speed is controlled by the automatic adjust-
ment type, it can not be adjusted manually. If the
idle speed is out of specifications, refer to General
On-board Diagnosis Table under “Engine Control
System”. tics Procedure.>