2004 SUBARU FORESTER check engine

4AT(H4SO)-42
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ENGINE GROUND TERMINALS.Have engine ground terminals
been tightened?Go to step 2.Tighten the engine
ground terminals.
2 CHECK GROUND CIRCUIT OF ECM.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM.
3) Measure the resistance of harness
between ECM and engine ground.
Connector & terminal
(B134) No. 7 — Engine ground:
(B134) No. 35 — Engine ground:
(B135) No. 21 — Engine ground:
(B136) No. 26 — Engine ground:
(B136) No. 5 — Engine ground:
(B136) No. 16 — Engine ground:
(B137) No. 14 — Engine ground:Is the resistance less than 5
Ω?Go to step 3.Repair the open
circuit in harness
between ECM
connector and
engine grounding
terminal.
3 CHECK THROTTLE POSITION SENSOR.
1) Disconnect the connector from throttle
position sensor.
2) Measure the resistance between throttle
position sensor connector receptacle’s terminals.
Te r m i n a l s
No. 4 — No. 2:Is the resistance 3.0 — 4.2
kΩ?Go to step 4.Replace the throt-
tle position sensor.
4 CHECK THROTTLE POSITION SENSOR.
Measure the resistance between throttle posi-
tion sensor connector receptacle’s terminals.
Te r m i n a l s
No. 2 — No. 3:Is the resistance 0.35 — 0.5
kΩ?Go to step 5.Replace the throt-
tle position sensor.
5 CHECK HARNESS CONNECTOR BETWEEN
TCM AND THROTTLE POSITION SENSOR.
1) Disconnect the connector from TCM.
2) Measure the resistance of harness
between TCM and throttle position sensor con-
nector.
Connector & terminal
(B54) No. 3 — (E13) No. 3:Is the resistance less than 1
Ω?Go to step 6.Repair the open
circuit in harness
between TCM and
throttle position
sensor connector,
and poor contact
in coupling con-
nector.
6 CHECK HARNESS CONNECTOR BETWEEN
TCM AND THROTTLE POSITION SENSOR.
Measure the resistance of harness between
TCM and throttle position sensor connector.
Connector & terminal
(B54) No. 2 — (E13) No. 4:Is the resistance less than 1
Ω?Go to step 7.Repair the open
circuit in harness
between TCM and
throttle position
sensor connector,
and poor contact
in coupling con-
nector.
7 CHECK HARNESS CONNECTOR BETWEEN
TCM AND THROTTLE POSITION SENSOR.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B54) No. 3 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 8.Repair the short
circuit in harness
between TCM and
throttle position
sensor connector.
8 CHECK HARNESS CONNECTOR BETWEEN
TCM AND THROTTLE POSITION SENSOR.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B54) No. 2 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 9.Repair the short
circuit in harness
between TCM and
throttle position
sensor connector.

4AT(H4SO)-43
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
9 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ECM.
Measure the resistance of harness between
TCM and ECM connector.
Connector & terminal
(B54) No. 3 — (B135) No. 13:Is the resistance less than 1
Ω?Go to step 10.Repair the open
circuit in harness
between TCM and
ECM connector.
10 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ECM.
Measure the resistance of harness between
TCM and ECM connector.
Connector & terminal
(B54) No. 2 — (B135) No. 19:Is the resistance less than 1
Ω?Go to step 11.Repair the open
circuit in harness
between TCM and
ECM connector.
11 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 14.Go to step 12.
12 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM, throttle
position sensor and ECM.
2) Turn the ignition switch to ON (engine
OFF).
3) Close the throttle completely.
4) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B54) No. 3 (+) — Chassis ground (
−):Is the voltage 0.2 — 1.0 V? Go to step 13.Go to step 18.
13 CHECK INPUT SIGNAL FOR TCM.
1) Open the throttle completely.
2) Measure the voltage between TCM con-
nector and chassis ground.
Connector & terminal
(B54) No. 3 (+) — Chassis ground (
−):Is the voltage 4.2 — 4.7 V? Go to step 16.Go to step 18.
14 CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect the connectors to TCM, throttle
position sensor and ECM.
2) Connect the Subaru Select Monitor to data
link connector.
3) Turn the ignition switch to ON (engine
OFF).
4) Turn the Subaru Select Monitor switch to
ON.
5) Throttle fully closed.
6) Read the data of throttle position sensor
using Subaru Select Monitor.
 Throttle position sensor input signal is indi-
cated.Is the value voltage 0.2 — 1.0
V?Go to step 15.Go to step 18.
15 CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
Throttle fully open.
N
OTE:
Must be changed correspondingly with the ac-
celerator pedal operation (from “released” to
“depressed” position).Is the value voltage 4.2 — 4.7
V?Go to step 17.Go to step 18. Step Check Yes No

4AT(H4SO)-47
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. 18 — (B11) No. 17: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
(B54) No. 10 — (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 chassis ground.
Connector & terminal
(B54) No. 10 — 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 chassis ground.
Connector & terminal
(B55) No. 18 — 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. 17 — 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 or raise the vehicle and place rigid
rack.
NOTE:
Raise all wheels off floor.
3) Start the engine and set vehicle in 20 km/h
(12 MPH) condition.
NOTE:
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
clearance procedure of on-board diagnostics
system. Mode.>
4) Measure the voltage between TCM con-
nector terminals.
Connector & terminal
(B55) No. 18 (+) — (B54) No. 10 (
−):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(H4SO)-48
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 rack.
N
OTE:
Raise all wheels off ground.
3) Set the oscilloscope to TCM connector ter-
minals.
Connector & terminal
Positive probe; (B55) No. 18
Earth lead; (B54) No. 10
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 self-diagnosis system.

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 nor-
mal condition at
this time. A tempo-
rary poor contact
or harness may be
the cause. Repair
the harness or
connector in front
vehicle speed sen-
sor circuit.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 or raise the vehicle and place rigid
rack.
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
clearance procedure of on-board diagnostics
system. Mode.>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 nor-
mal condition at
this time. A tempo-
rary poor connec-
tor or harness may
be the cause.
Repair the har-
ness or connector
in front vehicle
speed sensor cir-
cuit.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(H4SO)-50
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK TORQUE CONVERTER TURBINE
SPEED SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from transmis-
sion.
3) Measure the resistance between transmis-
sion connector receptacle’s terminals.
Connector & terminal
(T4) No. 14 — No. 15:Is the resistance 450 — 650
Ω?Go to step 2.Replace the tur-
bine speed sensor.
Torque Converter
Turbine Speed
Sensor.>
2 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
1) Disconnect the connector from TCM.
2) Measure the resistance of harness
between TCM and transmission connector.
Connector & terminal
(B55) No. 8 — (B11) No. 14:Is the resistance less than 1
Ω?Go to step 3.Repair the open
circuit in harness
between TCM and
transmission con-
nector.
3 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness between
TCM and transmission connector.
Connector & terminal
(B55) No. 9 — (B11) No. 15:Is the resistance less than 1
Ω?Go to step 4.Repair the open
circuit in harness
between TCM and
transmission con-
nector, and poor
contact in cou-
pling connector.
4 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness between
TCM and chassis ground.
Connector & terminal
(B55) No. 9 — 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.
5 CHECK HARNESS CONNECTOR BETWEEN
TCM AND TRANSMISSION.
Measure the resistance of harness between
TCM and chassis ground.
Connector & terminal
(B55) No. 8 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 6.Repair the short
circuit in harness
between TCM and
transmission con-
nector, and poor
contact in cou-
pling connector.
6 PREPARE OSCILLOSCOPE.Do you have an oscilloscope? Go to step 10.Go to step 7.
7 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 9.Go to step 8.
8 CHECK INPUT SIGNAL FOR TCM.
1) Connect the connectors to TCM and trans-
mission.
2) Start the engine and move select lever to
“P” or “N” range.
3) Measure the voltage between TCM con-
nector terminals.
Connector & terminal
(B55) No. 8 (+) — No. 9 (
−):Is the voltage more than AC 1
V?Even if the
POWER indicator
lights up, the cir-
cuit has returned
to a normal condi-
tion at this time. A
temporary poor
contact of the con-
nector or harness
may be the cause.
Repair the har-
ness or connector
in TCM and trans-
mission.Go to step 11.

4AT(H4SO)-51
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
9 CHECK INPUT SIGNAL FOR TCM USING
SUBARU SELECT MONITOR.
1) Connect the connectors to TCM and trans-
mission.
2) Connect the Subaru Select Monitor to data
link connector.
3) Turn the ignition switch to ON and turn Sub-
aru Select Monitor switch to ON.
4) Start the engine.
5) Move the select lever to “P” or “N” range.
6) Read the data of turbine speed using Sub-
aru Select Monitor.
 Compare the tachometer with Subaru Select
Monitor indications.Is the revolution value same as
the tachometer reading shown
on the combination meter?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
of the connector or
harness may be
the cause. Repair
the harness or
connector in TCM
and transmission.Go to step 11.
10 CHECK INPUT SIGNAL FOR TCM USING
OSCILLOSCOPE.
1) Connect the connectors to TCM and trans-
mission.
2) Set the oscilloscope to TCM connector ter-
minals.
Connector & terminal
Positive probe; (B55) No. 8
Earth lead; (B55) No. 9
3) Start the engine and move select lever to
“P” or “N” range.Is the signal 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
of the connector or
harness may be
the cause. Repair
the harness or
connector in TCM
and transmission.Go to step 11.
11 CHECK POOR CONTACT.Is there poor contact in torque
converter turbine speed sensor
circuit?Repair the poor
contact.Replace the TCM.
Transmission Con-
trol Module
(TCM).> Step Check Yes No

4AT(H4SO)-53
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
3 CHECK OUTPUT SIGNAL EMITTED FROM
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 terminals.
Connector & terminal
(B56) No. 14 (+) — Chassis ground (
−):
(B56) No. 5 (+) — Chassis ground (
−):Is the voltage more than 4.8 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
of the connector or
harness may be
the cause. Repair
the harness or
connector in TCM
and ECM.Go to step 4.
4 CHECK POOR CONTACT.Is there poor contact in torque
control signal circuit?Repair the poor
contact.Go to step 5.
5 CHECK GROUND LINE BETWEEN TRANS-
MISSION AND BODY.
Check installing condition of the ground line in
transmission and body.Is there any dirt or rust at the
ground line installing point?Remove dirt and
rust.Go to step 6.
6 CHECK GROUND LINE BETWEEN TRANS-
MISSION AND BODY.
Check installing condition of the ground line in
transmission and body.Is the tightening torque value
13 N⋅m (1.3 kgf-m, 9.4 ft-lb)?Go to step 7.Tighten to the
specified torque.
7 CHECK GROUND LINE INSIDE TRANSMIS-
SION.
1) Drain the ATF and remove oil pan.
2) Check the tightening torque value of ground
line installing bolt.Is the tightening torque value 8
N⋅m (0.8 kgf-m, 5.8 ft-lb)?Go to step 8.Tighten to the
specified torque.
8 CHECK GROUND CIRCUIT OF ECM.
POSITION SENSOR, Diagnostic Procedure
with Diagnostic Trouble Code (DTC).>Is there any trouble? Repair the ground
terminal and/or
ground circuit of
ECM.Go to step 9.
9 RECHECK OUTPUT SIGNAL EMITTED
FROM TCM.
Measure the voltage between TCM connector
and chassis ground.
Connector & terminal
(B56) No. 14 (+) — Chassis ground (
−):
(B56) No. 5 (+) — Chassis ground (
−):Is the voltage more than 4 V? Replace the TCM.
Transmission Con-
trol Module
(TCM).>Replace the ECM. Step Check Yes No

4AT(H4SO)-54
AUTOMATIC TRANSMISSION (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
G: DTC 45 INTAKE MANIFOLD PRESSURE SIGNAL
DTC DETECTING CONDITION:
The input signal circuit of TCM from ECM is open or shorted.
TROUBLE SYMPTOM:
Excessive shift shock.
WIRING DIAGRAM:
Step Check Yes No
1 CHECK ENGINE GROUND TERMINALS AND
GROUND CIRCUIT OF ECM
POSITION SENSOR, Diagnostic Procedure
with Diagnostic Trouble Code (DTC).>Is there any trouble? Repair the ground
terminal and/or
ground circuit of
ECM.Go to step 2.
2 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
(B54) No. 1 — (B137) No. 2:Is the resistance less than 1
Ω?Go to step 3.Repair the open
circuit in harness
between TCM and
ECM connector.
3 CHECK HARNESS CONNECTOR BETWEEN
TCM AND ECM.
Measure the resistance of harness between
TCM connector and chassis ground.
Connector & terminal
(B54) No. 1 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 4.Repair the short
circuit in harness
between TCM and
ECM connector.
4 PREPARE SUBARU SELECT MONITOR.Do you have a Subaru Select
Monitor?Go to step 6.Go to step 5.
AT-00582
2
1
B54
B54
B137
B137ECM
TCM
1234
56789
10 1112
13 14 15 16 17 18
19204
5
17
12
89
20
3
1011 12
1314 151667
18
19
21
2223 24