SUBARU LEGACY 1997 Service Repair Manual

B2M1069
J: DTC P0121
—THROTTLE POSITION SENSOR CIRCUIT
RANGE/PERFORMANCE PROBLEM (HIGH
INPUT)—
DTC DETECTING CONDITION:

Two consecutive driving cycles with fault
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
WIRING DIAGRAM:
B2M0540
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

160
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10J1CHECK DTC P0122 OR P0123 ON DIS-
PLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0122 or
P0123?
: Inspect DTC P0122 or P0123 using“10. Diagnos-
tics Chart with Trouble Code”. [T10A0].>
NOTE:
In this case, it is not necessary to inspect DTC P0121.
: Replace throttle position sensor.
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B2M1070
K: DTC P0122
—THROTTLE POSITION SENSOR CIRCUIT
LOW INPUT—
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
WIRING DIAGRAM:
B2M0540
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

162
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10. Diagnostic Chart with Trouble Code for LHD Vehicles

OBD0145A
10K1CONNECT 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.
B2M0482
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F07

F07: Throttle position sensor output signal is indicated.
: Is the value less than 0.1 V in function
mode F07?
: Go to step10G2.
: Even if MIL lights up, the circuit has returned to a
normal condition at this time. A temporary poor
contact of the connector may be the cause.
NOTE:
In this case, repair the following:

Poor contact in throttle position sensor connector

Poor contact in ECM connector

Poor contact in coupling connector (B21)

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
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B2M0541A
10K2CHECK INPUT SIGNAL FOR ECM.
(USING VOLTAGE METER AND SUBARU
SELECT MONITOR.)
1) Measure voltage between ECM connector and chassis
ground while throttle valve is fully closed.
: Connector & terminal
(B84) No. 21 (+)—Chassis ground ():
Is the voltage more than 4.5 V?
: Go to next step 2).
: Go to next.
: Does the voltage change more than 4.5 V by
shaking harness and connector of ECM
while monitoring the value with voltage
meter?
: Repair poor contact in ECM connector.
: Contact with SOA service.
NOTE:
Inspection by DTM is required, because probable cause is
deterioration of multiple parts.
B2M0542A
2) Measure voltage between ECM connector and chassis
ground.
: Connector & terminal
(B84) No. 6 (+)—Chassis ground ():
Is the voltage less than 0.1 V?
: Go to step10K3.
: Go to next.
B2M0482
: Does the voltage change more than 0.1 V by
shaking harness and connector of ECM
while monitoring the value with Subaru
select monitor?
: Repair poor contact in ECM connector.
: Go to step10K3.
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OBD0700A
10K3CHECK 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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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 ground 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.
166
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10. Diagnostic Chart with Trouble Code for LHD Vehicles

B2M1071
L: DTC P0123
—THROTTLE POSITION SENSOR CIRCUIT
HIGH INPUT—
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
WIRING DIAGRAM:
B2M0540
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

167
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

OBD0145A
10L1CONNECT 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.
B2M0482
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F07

F07: Throttle position sensor output signal is indicated.
: Is the value more than 4.9 V in function
mode F07?
: Go to step10L2.
: Even if MIL lights up, the circuit has returned to a
normal condition at this time. A temporary poor
contact of the connector may be the cause.
NOTE:
In this case, repair the following:

Poor contact in throttle position sensor connector

Poor contact in ECM connector

Poor contact in coupling connector (B21)

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
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OBD0703A
10L2CHECK 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 battery short circuit in harness between
throttle position sensor and ECM connector. After
repair, replace ECM.
: Replace throttle position sensor.
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10. Diagnostic Chart with Trouble Code for LHD Vehicles