check engine SUBARU LEGACY 1996 Service Repair Manual

OBD0181
G: DTC P0120
—THROTTLE POSITION SENSOR CIRCUIT
MALFUNCTION (THV)—
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
10G1Connect Subaru Select Monitor or the OBD-II
general scan tool and read data.

10G2Check input signal for ECM. (Using voltage
meter and Subaru select monitor.)
10G3Check harness between ECM and throttle
position sensor connector.
10G4Check harness between throttle position
sensor and body connector.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.



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10. Diagnostics Chart with Trouble Code

OBD0700A
10G3CHECK HARNESS BETWEEN ECM AND
THROTTLE POSITION SENSOR CON-
NECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connectors from throttle position sensor.
3) Turn ignition switch to ON.
4) Measure voltage between throttle position sensor con-
nector and engine ground.
: Connector & terminal
(E13) No. 3 (+)—Engine ground ():
Is the voltage more than 4.5 V?
: Go to next step 5).
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between throttle position sensor
and ECM connector

Poor contact in throttle position sensor connector

Poor contact in ECM connector

Poor contact in coupling connector (B21)
B2M0543A
5) Turn ignition switch to OFF.
6) Measure resistance of harness between ECM connec-
tor and throttle position sensor connector.
: Connector & terminal
(B84) No. 6—(E13) No. 2:
Is the resistance less than 1Ω?
: Go to next step 7).
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between throttle position sensor
and ECM connector

Poor contact in ECM connector

Poor contact in throttle position sensor connector

Poor contact in coupling connector (B21)
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10. Diagnostics Chart with Trouble Code

OBD0702A
7) Measure resistance of harness between throttle posi-
tion sensor connector and engine ground.
: Connector & terminal
(E13) No. 2—Engine ground:
Is the resistance less than 10Ω?
: Repair short circuit in harness between throttle
position sensor and ECM connector.
: Go to next.
: Is there poor contact in throttle position
sensor connector?
: Repair poor contact in throttle position sensor
connector.
: Replace throttle position sensor.
OBD0703A
10G4CHECK HARNESS BETWEEN THROTTLE
POSITION SENSOR AND BODY CON-
NECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from throttle position sensor.
3) Measure resistance of harness between throttle posi-
tion sensor connector and engine ground.
: Connector & terminal
(E13) No. 1—Engine ground:
Is the resistance less than 5Ω?
: Go to next step 4).
: Repair open circuit in harness between throttle
position sensor and ECM connector.
OBD0704A
4) Turn ignition switch to ON.
5) Measure voltage between throttle position sensor con-
nector and engine ground.
: Connector & terminal
(E13) No. 2 (+)—Engine ground ():
Is the voltage more than 4.9 V?
: Repair short circuit in harness between throttle
position sensor and ECM connector.
: Replace throttle position sensor.
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10. Diagnostics Chart with Trouble Code

OBD0189
H: DTC P0121
—THROTTLE POSITION SENSOR CIRCUIT
RANGE/PERFORMANCE PROBLEM
(TH
—R)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
10H1Check DTC P0120 on display.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:
B2M0540
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10. Diagnostics Chart with Trouble Code

OBD0191
I: DTC P0125
—INSUFFICIENT COOLANT TEMPERATURE
FOR CLOSED LOOP FUEL CONTROL
(TW
—CL)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Engine would not return to idling.
10I1Check DTC P0115 on display.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:
B2M0539
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10. Diagnostics Chart with Trouble Code

10I1
CHECK DTC P0115 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0115?
: Inspect DTC P0115 using“10. Diagnostics Chart
with Trouble Code 2-7 [T1000]”.
NOTE:
In this case, it is not necessary to inspect DTC P0125.
: Replace engine coolant temperature sensor.
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10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD Model
B2M0787
10J1CHECK FOR OTHER CAUSES AFFECT-
ING EXHAUST GAS.
: Is CO % more than 2 % after engine warm-
up?
: Check fuel system.
NOTE:

Check for use of improper fuel.

Check if engine oil or coolant level is extremely low.
: Go to step10J2.
OBD0145A
10J2
CHECK FRONT OXYGEN SENSOR DATA.
1) Turn ignition switch to OFF.
2) Connect the Subaru Select Monitor or the OBD-II gen-
eral scan tool to data link connector.
3) Start engine and Turn the Subaru Select Monitor and
the OBD-II general scan tool switch to ON.
4) Warm-up the engine until coolant temperature is above
70°C (160°F) and keep the engine speed at 2,000 rpm to
3,000 rpm for one minute.
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10. Diagnostics Chart with Trouble Code

B2M0487
5) Read data on Subaru Select Monitor or the OBD-II gen-
eral scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F12

F12: Front oxygen sensor max. and min. output signals
are indicated at the same time.
: Is the difference of voltage less than 0.1 V
between the value of max. output and min.
output with function mode F12?
: Go to step10J3.
: Replace front oxygen sensor.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
B2M0545A
10J3CHECK HARNESS BETWEEN FRONT
OXYGEN SENSOR AND ECM CONNEC-
TOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from front oxygen sensor.
3) Turn ignition switch to ON.
4) Measure voltage between front oxygen sensor harness
connector and engine ground.
: Connector & terminal
(B18) No. 3 (+)—Engine ground ():
Is the voltage more than 0.2 V?
: Go to next.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between ECM and front oxygen
sensor connector

Poor contact in the ECM connector
: Is there poor contact in front oxygen sensor
connector?
: Repair poor contact in front oxygen sensor con-
nector.
: Replace front oxygen sensor.
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10. Diagnostics Chart with Trouble Code

10L1
CHECK DTC P0141 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0135 and
P0141 at the same time?
: Go to next step 1).
: Go to step10L2.
B2M0547A
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between ECM connec-
tor and chassis ground.
: Connector & terminal
(B84) No. 42—Chassis ground:
Is the resistance less than 5Ω?
: Repair poor contact in ECM connector.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between ECM and coupling con-
nector (B22)

Open circuit in harness between coupling connector
(B22) and engine grounding terminal

Poor contact in front oxygen sensor connector

Poor contact in coupling connector (B22)
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10. Diagnostics Chart with Trouble Code

OBD0145A
10L2CONNECT SUBARU SELECT MONITOR
OR THE OBD-II GENERAL SCAN TOOL,
AND READ DATA.
1) Turn ignition switch to OFF.
2) Connect Subaru Select Monitor or the OBD-II general
scan tool to data link connector.
3) Turn ignition switch to ON and Subaru Select Monitor or
OBD-II general scan tool switch to ON.
4) Start engine.
B2M0497
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F32

F32: Front oxygen sensor heater current is indicated.
: Is the value more than 0.2 A in function
mode F32?
: Repair connector.
NOTE:
In this case, repair the following:

Poor contact in front oxygen sensor connector

Poor contact in ECM connector
: Go to step10L3.

OBD-II scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
B2M0548A
10L3CHECK OUTPUT SIGNAL FROM ECM.
(USING VOLTAGE METER.)
1) Start and idle the engine.
2) Measure voltage between ECM connector and chassis
ground.
: Connector & terminal
(B84) No. 38 (+)—Chassis ground ():
Is the voltage less than 1.0 V?
: Go to step10L4.
: Go to next.
: Does the voltage change less than 1.0 V by
shaking harness and connector of ECM
while monitoring the value with voltage
meter?
: Repair poor contact in ECM connector.
: Go to next step 3).
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10. Diagnostics Chart with Trouble Code