ignition SUBARU FORESTER 2004 Service Repair Manual

4AT(H4DOTC)-53
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
3 CHECK HARNESS CONNECTOR BETWEEN
TCM AND STOP LIGHT SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from TCM and
stop light switch.
3) Measure the resistance of harness
between TCM and stop light switch.
Connector & terminal
(B55) No. 20 — (B65) No. 3:Is the resistance less than 1
Ω?Go to step 4.Repair the open
harness between
TCM and stop light
switch.
4 CHECK HARNESS CONNECTOR BETWEEN
TCM AND STOP LIGHT SWITCH.
Measure the resistance of harness between
TCM and chassis ground.
Connector & terminal
(B55) No. 20 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 5.Repair the short
circuit in harness
between TCM and
stop light switch.
5 INSPECT POOR CONTACT.Is there poor contact in the
stop light switch input signal
circuit?Repair poor con-
tact.Replace the TCM.
Transmission Con-
trol Module
(TCM).> Step Check Yes No

4AT(H4DOTC)-55
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from TCM and
transmission.
3) Measure the resistance of harness
between TCM and transmission connector.
Connector & terminal
(B55) No. 6 — (B11) No. 14:Is the resistance less than 1
Ω?Go to step 2.Repair the open
circuit in harness
between TCM and
transmission con-
nector.
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness between
TCM and transmission connector.
Connector & terminal
(B55) No. 15 — (B11) No. 18:Is the resistance less than 1
Ω?Go to step 3.Repair the open
circuit in harness
between TCM and
transmission con-
nector, and poor
contact in cou-
pling connector.
3 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness between
TCM and transmission connector.
Connector & terminal
(B55) No. 6 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 4.Repair the short
circuit in harness
between TCM and
transmission con-
nector.
4 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness between
TCM and transmission connector.
Connector & terminal
(B55) No. 15 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 5.Repair the short
circuit in harness
between TCM and
transmission con-
nector, and poor
contact in cou-
pling connector.
5 CHECK FRONT VEHICLE SPEED SENSOR.
Measure the resistance between transmission
connector receptacle’s terminals.
Connector & terminal
(T4) No. 14 — No. 18:Is the resistance 450 — 650
Ω?Go to step 6.Replace the front
vehicle speed sen-
sor. 55, Front Vehicle
Speed Sensor.>
6 PREPARE OSCILLOSCOPE.Do you have an oscilloscope? Go to step 9.Go to step 7.
7 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 10.Go to step 8.
8 CHECK INPUT SIGNAL FOR TCM.
1) Connect all connectors.
2) Lift-up the vehicle and place rigid racks.
N
OTE:
Raise all wheels off floor.
3) Start the engine and set vehicle in 20 km/h
(12 MPH) condition.
N
OTE:
The speed difference between front and rear
wheels may light the ABS warning light, but this
indicates no malfunction. When AT control diag-
nosis is finished, perform the ABS memory clear-
ance procedure of on-board diagnostics system.

4) Measure the voltage between TCM con-
nector terminals.
Connector & terminal
(B55) No. 6 (+) — No. 15 (
−):Is the voltage more than AC 1
V?Even if the
POWER indicator
light was blinking,
the circuit has
returned to a nor-
mal condition at
this time. A tempo-
rary poor contact
or harness may be
the cause. Repair
the harness or
connector in the
front vehicle speed
sensor circuit.Go to step 11.

4AT(H4DOTC)-56
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
9 CHECK FRONT VEHICLE SPEED SENSOR
USING OSCILLOSCOPE.
1) Connect all connectors.
2) Lift-up the vehicle and place rigid racks.
N
OTE:
Raise all wheels off ground.
3) Set the oscilloscope to TCM connector ter-
minals.
Connector & terminal
Positive probe; (B55) No. 6:
Earth lead; (B55) No. 15:
4) Start the engine, and drive the wheels
slowly.
N
OTE:
The speed difference between front and rear
wheels may light the ABS warning light, but this
indicates no malfunctions. When AT control di-
agnosis is finished, perform the ABS memory
clearance procedure of on-board diagnostic sys-
tem.
5) Measure the signal voltage indicated on
oscilloscope.Is the voltage more than AC 4
V?Even if the POWER
indicator light was
blinking, the circuit
has returned to a
normal condition at
this time. A tempo-
rary poor contact or
harness may be the
cause. Repair the
harness or connec-
tor in front vehicle
speed sensor cir-
cuit.Go to step 11.
10 CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect all connectors.
2) Connect the Subaru Select Monitor to data
link connector.
3) Lift-up the vehicle and place rigid racks.
N
OTE:
Raise all wheels off floor.
4) Turn the ignition switch to ON and turn Sub-
aru Select Monitor switch to ON.
5) Start the engine.
6) Read the data of vehicle speed using Sub-
aru Select Monitor.
 Compare the speedometer with Subaru
Select Monitor indications.
 Vehicle speed is indicated in “km/h” or
“MPH”.
7) Slowly increase the vehicle speed to 60 km/
h (37 MPH).
N
OTE:
The speed difference between front and rear
wheels may light the ABS warning light, but this
indicates no malfunction. When AT control diag-
nosis is finished, perform the ABS memory clear-
ance procedure of on-board diagnostics system.
Does the speedometer indica-
tion increase as Subaru Select
Monitor data increases?Even if the POWER
indicator light was
blinking, the circuit
has returned to a
normal condition at
this time. A tempo-
rary poor connec-
tor or harness may
be the cause.
Repair the harness
or connector in
front vehicle speed
sensor circuit.Go to step 11.
11 CHECK POOR CONTACT.Is there poor contact in front
vehicle speed sensor circuit?Repair the poor
contact.Replace the TCM.
Transmission Con-
trol Module
(TCM).> Step Check Yes No

4AT(H4DOTC)-58
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
2 CHECK STOP LIGHT SWITCH.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from stop light
switch.
3) Measure the resistance between stop light
switch connector.
Connector & terminal
No. 2 — No. 3:Is the resistance more than 1
MΩ?Go to step 3.Replace the stop
light switch.
3 CHECK HARNESS CONNECTOR BETWEEN
TCM AND STOP LIGHT SWITCH.
1) Turn the ignition switch to ON.
2) Measure the voltage of harness between
TCM and chassis ground.
Connector & terminal
(B55) No. 20 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 4.Repair the short in
power supply cir-
cuit to harness
between TCM and
stop light switch.
4 INSPECT POOR CONTACT.Is there poor contact in the
stop light switch input signal
circuit?Repair poor con-
tact.Replace the TCM.
Transmission Con-
trol Module
(TCM).> Step Check Yes No

4AT(H4DOTC)-59
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
H: DTC P0725 ENGINE SPEED INPUT CIRCUIT
DTC DETECTING CONDITION:
Engine speed input signal circuit is open or shorted.
TROUBLE SYMPTOM:
 No lock-up (after engine warm-up).
 POWER indicator light remains on when vehicle speed is “0”.
WIRING DIAGRAM:
Step Check Yes No
1 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from TCM and
ECM.
3) Measure the resistance of harness
between TCM and ECM connector.
Connector & terminal
(B55) No. 13 — (B134) No. 23:Is the resistance less than 1
Ω?Go to step 2.Repair the open
circuit in harness
between TCM and
ECM connector.
AT-01846
B55
23
13
B134
ECM
B55
TCM
B134
12
7
8956 3410 11 12
19 20 2113 14 15 16
17 1822
23
24
56 7
82 1
94 310
24 22 23 25 11 12 13 14 15
26 27
2816 17
18 19 20 21
33 34 29
32 30 31

4AT(H4DOTC)-60
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ECM.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B55) No. 13 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair the short
circuit in harness
between TCM and
ECM connector.
3 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 5.Go to step 4.
4 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM and ECM.
2) Turn the ignition switch to ON (engine OFF).
3) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B55) No. 13 (+) — Chassis ground (
−):Is the voltage less than 1 V? Even if the POWER
indicator light was
blinking, the circuit
has returned to a
normal condition at
this time. A tempo-
rary poor contact of
the connector or
harness may be the
cause. Repair the
harness or connec-
tor of TCM and
ECM.Go to step 6.
5 CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and ECM.
2) Connect the Subaru Select Monitor to data
link connector.
3) Start the engine and turn Subaru Select
Monitor switch to ON.
4) Idle the engine.
5) Read the data of engine speed using Sub-
aru Select Monitor.
 Display shows the engine speed signal value
sent from ECM.Is the revolution value same as
tachometer reading shown on
combination meter?Even if the POWER
indicator light was
blinking, the circuit
has returned to a
normal condition at
this time. A tempo-
rary poor contact of
the connector or
harness may be the
cause. Repair the
harness or connec-
tor of TCM and
ECM.Go to step 6.
6 CHECK POOR CONTACT.Is there poor contact in engine
speed signal circuit?Repair the poor
contact.Go to step 7.
7 CONFIRM DTC P0725.
Replace the ECM with a new one. Does the DTC appear again,
after memory has been
cleared?Replace the TCM.
Transmission Con-
trol Module
(TCM).>Replace the ECM.
FU(H4SO)-44,
Engine Control
Module (ECM).> Step Check Yes No

4AT(H4DOTC)-62
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
M: DTC P0736 REVERSE INCORRECT RATIO
DTC DETECTING CONDITION:
Vehicle speed sensor malfunction and torque converter turbine speed sensor malfunction, etc. or control
valve malfunction.
TROUBLE SYMPTOM:
 Shift point is too high or too low.
 Excessive shift shock.
 Tight corner “braking” phenomenon.
 Gear is not shifted to reverse.
 Gear position is held by fail safe function.
Step Check Yes No
1 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 2.Go to step 5.
2 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
1) Connect the Subaru Select Monitor to data
link connector.
2) Turn the ignition switch to ON.
3) Read the value of accelerator pedal posi-
tion sensor on Subaru Select Monitor.Does the value of accelerator
pedal position sensor change
from 0% to 100% smoothly
when throttle was operated from
fully closing to fully opening?Go to step 3.Check accelerator
pedal position sen-
sor. 4AT(H4DOTC)-94,
DTC P1708
THROTTLE POSI-
TION SENSOR
CIRCUIT LOW
INPUT, Diagnostic
Procedure with
Diagnostic Trou-
ble Code (DTC).>
3 CHECK FRONT VEHICLE SPEED SENSOR.
1) Lift-up the vehicle and place rigid racks.
2) Start the engine.
3) Move the select lever “D” range and slowly
increase vehicle speed.
NOTE:
The speed difference between front and rear
wheels may light ABS warning light, but this indi-
cates no malfunction. When AT control diagnosis
is finished, perform the ABS memory clearance
procedure of on-board diagnostics system.Does the vehicle speed dis-
played by Subaru Select Moni-
tor almost correspond with
vehicle speed indicated by
combination meter?Go to step 4.Check the front
vehicle speed sen-
sor.
4 CHECK TORQUE CONVERTER TURBINE
SPEED SENSOR.
1) Move the select lever to “P” or “N” range.
2) Idle the engine.Does the turbine speed sen-
sor revolution displayed by
Subaru Select Monitor almost
correspond with engine revolu-
tion indicated by tachometer?There are mal-
functions in TCM,
TCM connector
poor contact or
transmission
assembly mechan-
ical malfunction.Check the torque
converter turbine
speed sensor cir-
cuit.
5 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
1) Turn the ignition switch to ON.
2) Fully close the throttle.
3) Measure the voltage between TCM and
chassis ground.
Connector & terminal
(B55) No. 19 (+) — Chassis ground (
−):Is the voltage 0.8 — 1.2 V? Go to step 6.Check the acceler-
ator pedal position
sensor circuit.
4AT(H4DOTC)-94,
DTC P1708
THROTTLE POSI-
TION SENSOR
CIRCUIT LOW
INPUT, Diagnostic
Procedure with
Diagnostic Trou-
ble Code (DTC).>

4AT(H4DOTC)-64
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
N: DTC P0741 TORQUE CONVERTER CLUTCH CIRCUIT PERFORMANCE OR
STUCK OFF
DTC DETECTING CONDITION:
 Lock up clutch malfunction
 Locking of valve
TROUBLE SYMPTOM:
Lock up is not operated.
Step Check Yes No
1 CHECK LOCK UP DUTY SOLENOID CIR-
CUIT.
Check according as DTC P0743 procedure.Is there malfunction? Repair or replace
the lock up duty
solenoid circuit.Go to step 2.
2 CHECK INHIBITOR SWITCH CIRCUIT.
Check according as DTC P0705 procedure.Is there malfunction? Repair or replace
the inhibitor switch
circuit.Go to step 3.
3 CHECK STOP LIGHT SWITCH CIRCUIT.
Check according as DTC P0719 and DTC
P0724 procedure.Is there malfunction? Repair or replace
the stop light
switch circuit.Go to step 4.
4 CHECK ATF TEMPERATURE SENSOR CIR-
CUIT.
Check according to DTC P0712 and DTC
P0713 procedure.Is there malfunction? Repair or replace
the ATF tempera-
ture sensor circuit.Go to step 5.
5 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 6.Go to step 9.
6 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
1) Connect the Subaru Select Monitor to data
link connector.
2) Turn the ignition switch to ON.
3) Read the value of accelerator pedal posi-
tion sensor on Subaru Select Monitor display.Does the value of accelerator
pedal position sensor change
from 0% to 100% smoothly
when throttle was operated from
fully closing to fully opening?Go to step 7.Check the acceler-
ator pedal position
sensor circuit.
7 CHECK TORQUE CONVERTER TURBINE
SPEED SENSOR.
1) Move the select lever to “P” or “N” range.
2) Idle the engine.Does the turbine revolution dis-
played by Subaru Select Moni-
tor almost correspond with
engine revolution indicated by
tachometer?Go to step 8.Check the torque
converter turbine
speed sensor cir-
cuit.
8 CHECK ENGINE SPEED SIGNAL.
Idle the engine.Does the turbine revolution dis-
played by Subaru Select Moni-
tor almost correspond with
engine revolution indicated by
tachometer?There is malfunc-
tion in TCM, TCM
connector poor
contact or trans-
mission assembly
mechanical mal-
fuction.Check the engine
speed signal cir-
cuit.
9 CHECK ACCELERATOR PEDAL POSITION
SENSOR.
Check according to DTC P1708, DTC 1709
and DTC P1714 procedure.Is there a malfunction? Go to step 10.Repair or replace
the accelerator
pedal position sen-
sor circuit.
10 CHECK TORQUE CONVERTER TURBINE
SPEED SENSOR.
Check according to DTC P0715 procedure.Is there a malfunction? Go to step 11.Repair or replace
the torque converter
turbine speed sen-
sor circuit.
11 CHECK ENGINE SPEED SIGNAL.
Check according to DTC P0725 procedure.Is there a malfunction? Repair or replace
the engine speed
signal circuit. There is malfunc-
tion in TCM, TCM
connector poor
contact or trans-
mission assembly
mechanical mal-
function.

4AT(H4DOTC)-65
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
O: DTC P0743 TORQUE CONVERTER CLUTCH CIRCUIT ELECTRICAL
DTC DETECTING CONDITION:
Output signal circuit of lock-up duty solenoid is open or shorted.
TROUBLE SYMPTOM:
No “lock-up” (after engine warm-up).
WIRING DIAGRAM:
Step Check Yes No
1 CHECK DTC.Are multiple DTCs indicated? Go to another
DTC.Go to step 2.
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from TCM and
transmission.
3) Measure the resistance of harness
between TCM and transmission connector.
Connector & terminal
(B56) No. 5 — (B11) No. 12:Is the resistance less than 1
Ω?Go to step 3.Repair the open
circuit in harness
between TCM and
transmission con-
nector.
AT-01117
B11
B56
AT12
1
234
56
78
9
1314
15
20
19 1716 10 1112
18
5
B56
B11
AT12
T4 TCM12 4
12 78 956 34
10 11 12 19 20 21
29 30 31 13 14 15 16 17
27 2818
22 23 24 25 26
13
4562
LOCK-UP
DUTY
SOLENOID
TRANSMISSION

4AT(H4DOTC)-69
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
P: DTC P0748 PRESSURE CONTROL SOLENOID “A” ELECTRICAL
DTC DETECTING CONDITION:
Output signal circuit of line pressure linear solenoid is open or shorted.
TROUBLE SYMPTOM:
Excessive shift shock.
WIRING DIAGRAM:
Step Check Yes No
1 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from transmis-
sion and TCM.
3) Measure the resistance of harness
between TCM and transmission connector.
Connector & terminal
(B56) No. 19 — (B11) No. 2:
(B56) No. 20 — (B11) No. 1:Is the resistance less than 1
Ω?Go to step 2.Repair the open
circuit in harness
between TCM and
transmission con-
nector.
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND CHASSIS GROUND.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B56) No. 19 — Chassis ground:
(B56) No. 20 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 3.Repair the short
circuit in harness
between TCM and
transmission con-
nector.
3 CHECK LINE PRESSURE LINEAR SOLE-
NOID.
Measure the resistance between transmission
connector receptacle’s terminals.
Connector & terminal
(T4) No. 1 — No. 2:Is the resistance 4 — 6 Ω? Go to step 4.Go to step 10.
AT-01847
19
B56
B11
AT11
T4 TCM
B11
1
234
56
78
9
1314
15
20
19 1716 10 1112
18
422021
B56AT11
12 78 956 34
10 11 12 19 20 21
29 30 31 13 14 15 16 17
27 2818
22 23 24 25 263412
TRANSMISSIONLINE
PRESSURE
LINEAR
SOLENOID