2004 SUBARU FORESTER engine

EN(H4DOTC 2.5)-181
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AY:DTC P0851 NEUTRAL SWITCH INPUT CIRCUIT LOW (MT MODEL)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Erroneous idling.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode OPERATION, Clear Memory Mode.> and Inspection Mode Inspection Mode.>.
WIRING DIAGRAM:
EN-02370
B12T3
B14
T7
PRND321
12
7
12
11
B12
T7
123456789101112
123
4
56
78
9
1011 12
B137
9
16
E2
E
B21
B21
12345678910111213141516
B128
T91
3B128
T9
B128
1
43 2
M
B137
MT
AT
567
82 1
94 310
22 23 11 12 13 14 15
24 25
2616 17
18 19 20 21
27 28 29 30 31
INHIBITOR SWITCH
STARTER MOTOR ECM
NEUTRAL
POSITION
SWITCH

EN(H4DOTC 2.5)-182
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
(B137) No. 9 (+) — 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
(B137) No. 9 (+) — 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
(T9) No. 1 — No. 3: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.
Te r m i n a l s
No. 1 — No. 3: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
(B137) No. 9 — 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 connector.
Connector & terminal
(B137) No. 9 — (B128) No. 1:Is the resistance less than 1
Ω?Go to step 8.Repair open circuit
in harness
between ECM and
transmission har-
ness connector.
8 CHECK HARNESS BETWEEN ECM AND
NEUTRAL POSITION SWITCH CONNEC-
TOR.
Measure the resistance of harness between
transmission harness connector and engine
ground.
Connector & terminal
(B128) No. 1 — Engine ground:Is the resistance less than 5
Ω?Go to step 9.Repair open circuit
between transmis-
sion harness con-
nector and engine
ground terminal.
9 CHECK POOR CONTACT.
Check poor contact in transmission harness
connector.Is there poor contact in trans-
mission harness connector?Repair poor con-
tact in transmission
harness connector.Contact the SUB-
ARU dealer.

EN(H4DOTC 2.5)-183
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AZ:DTC P0852 NEUTRAL SWITCH INPUT CIRCUIT HIGH (AT MODEL)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Erroneous idling.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode OPERATION, Clear Memory Mode.> and Inspection Mode Inspection Mode.>.
WIRING DIAGRAM:
EN-02370
B12T3
B14
T7
PRND321
12
7
12
11
B12
T7
123456789101112
123
4
56
78
9
1011 12
B137
9
16
E2
E
B21
B21
12345678910111213141516
B128
T91
3B128
T9
B128
1
43 2
M
B137
MT
AT
567
82 1
94 310
22 23 11 12 13 14 15
24 25
2616 17
18 19 20 21
27 28 29 30 31
INHIBITOR SWITCH
STARTER MOTOR ECM
NEUTRAL
POSITION
SWITCH

EN(H4DOTC 2.5)-184
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) Measure the voltage between ECM and
chassis ground with select lever at “N” and “P”
ranges.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 2.Go to step 4.
2 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
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage 4.5 — 5.5 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.
N
OTE:
Inspection by DTM
is required, because
probable cause is
deterioration of mul-
tiple parts.
4 CHECK INPUT SIGNAL FROM ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B137) No. 9 (+) — 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 5.
5 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
(B137) No. 9 — (T7) No. 12: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 inhibitor
switch connector.
 Poor contact in
coupling connector
 Poor contact in
inhibitor switch
connector
 Poor contact in
ECM connector.

EN(H4DOTC 2.5)-185
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
6 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 7.Repair open circuit
in harness between
inhibitor switch con-
nector and starter
motor ground line.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
inhibitor switch con-
nector and starter
motor ground line
 Poor contact in
starter motor con-
nector
 Poor contact in
starter motor
ground
 Starter motor
7 CHECK INHIBITOR SWITCH.
Measure the resistance between inhibitor
switch connector receptacle’s terminals with
select lever at “N” and “P” ranges.
Te r m i n a l s
No. 7 — No. 12:Is the resistance less than 1
Ω?Go to step 8.Replace the inhibi-
tor switch. 4AT-51, Inhibitor
Switch.>
8 CHECK SELECTOR CABLE CONNECTION.Is there any fault in selector
cable connection to inhibitor
switch?Repair selector
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. Step Check Yes No

EN(H4DOTC 2.5)-186
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BA:DTC P0852 NEUTRAL SWITCH INPUT CIRCUIT HIGH (MT MODEL)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Erroneous idling.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode OPERATION, Clear Memory Mode.> and Inspection Mode Inspection Mode.>.
WIRING DIAGRAM:
EN-02370
B12T3
B14
T7
PRND321
12
7
12
11
B12
T7
123456789101112
123
4
56
78
9
1011 12
B137
9
16
E2
E
B21
B21
12345678910111213141516
B128
T91
3B128
T9
B128
1
43 2
M
B137
MT
AT
567
82 1
94 310
22 23 11 12 13 14 15
24 25
2616 17
18 19 20 21
27 28 29 30 31
INHIBITOR SWITCH
STARTER MOTOR ECM
NEUTRAL
POSITION
SWITCH

EN(H4DOTC 2.5)-187
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 except in neutral posi-
tion.
3) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 2.Go to step 4.
2 CHECK INPUT SIGNAL FROM ECM.
1) Place the shift lever in neutral position.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage more than 10 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 INPUT SIGNAL FROM ECM.
1) Disconnect the connector from ECM.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B137) No. 9 (+) — Chassis ground (
−):Is the voltage more than 10 V? Repair battery
short circuit in har-
ness between
ECM and trans-
mission harness
connector.Go to step 5.
5 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 (T9).
3) Measure the resistance of harness
between ECM and neutral switch connector.
Connector & terminal
(B137) No. 9 — (B128) No. 1:Is the resistance less than 1
Ω?Go to step 6.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and trans-
mission harness
connector
 Poor contact in
transmission har-
ness connector.
 Poor contact in
ECM connector.
6 CHECK NEUTRAL POSITION SWITCH
GROUND LINE.
Measure the resistance of harness between
transmission harness connector and engine
ground.
Connector & terminal
(B128) No. 3 — Engine ground:Is the resistance less than 5
Ω?Go to step 7.Repair open circuit
in the neutral posi-
tion switch ground
line.
7 CHECK NEUTRAL POSITION SWITCH.
1) Place the shift lever except in neutral posi-
tion.
2) Measure the resistance between transmis-
sion harness connector socket terminals.
Te r m i n a l s
No. 1 — No. 3:Is the resistance less than 1
Ω?Go to step 8.Replace the neu-
tral position switch.
8 CHECK POOR CONTACT.
Check poor contact in transmission harness
connector.Is there poor contact in trans-
mission harness connector?Repair poor contact
in transmission har-
ness connector.Contact the SUB-
ARU dealer.

EN(H4DOTC 2.5)-188
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
BB:DTC P1086 TUMBLE GENERATED VALVE POSITION SENSOR 2 CIRCUIT
LOW
DTC DETECTING CONDITION:
Immediately at fault recognition
TROUBLE SYMPTOM:
 Erroneous idling
 Engine stalls.
 Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode OPERATION, Clear Memory Mode.> and Inspection Mode Inspection Mode.>.
WIRING DIAGRAM:
EN-02371
E3
B22
1
32
B136
16
35 26
B136
E50
123
B22
125678
131415169101112
34
17181920
B122
56
782 1
94 310
24 22 23 2511 12 13
1415
26 27
2816
17 18 19 20 21
33 34 29
32 30
31 35
ECM
20
18 10
1 2
B122
E50 TUMBLE GENERATOR VALVE
POSITION SENSOR LH
12345678