sensor SUBARU LEGACY 1995 Service Repair Manual

OBD0154
D: DTC P0105
—PRESSURE SENSOR CIRCUIT
MALFUNCTION (P
—S)—
OBD0155A
DESCRIPTION:
The pressure sensor is used in AT vehicles. It is located in
the engine compartment, at the front of the right-hand sus-
pension. It consists of a solenoid, which switches between
the atmospheric pressure and suction pressure lines and a
pressure sensor. This arrangement allows either pressure
line to be monitored.
A sensor output signal is sent to the ECM to diagnose the
EGR system and evaporative emission control system.
(The pressure sensor is not used in MT vehicles.)
DTC DETECTING CONDITION:

Immediately at fault recognition
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11. Diagnostics Chart with Trouble Code

1.Check transmission type.
AT
MT
Check AT/MT identification circuit. [T11BN0].>
2.Connect Subaru Select Monitor or the OBD-II
general scan tool, and read data.
3.Check input signal for ECM. (Using voltage
meter and Subaru Select Monitor.)
4.Check harness connector between ECM and
pressure sensor.
5.Check harness connector between ECM and
pressure sensor.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. [T3D0] and [T3E0].>
WIRING DIAGRAM:

LHD model
B2M0624




145
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11. Diagnostics Chart with Trouble Code

1
CHECK TRANSMISSION TYPE.
Refer to the flow chart on page 145.
OBD0145A
OBD0620
OBD0641
2CONNECT 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
the OBD-II general scan tool switch to ON.
4) Start engine.
5) Read the data on Subaru Select Monitor or the OBD-II
general scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F24 or F49

F24: Display shows voltage signal value sent from pres-
sure sensor.

F49: Display shows pressure signal value sent from
pressure sensor.
: Less than 0.2 V or 0 kPa
: Go to step 3.
: Go to next.
: More than 4.9 V or 140 kPa
: Go to step 5.
: Repair the harness and connector between pres-
sure sensor and ECM.
HINT:
1Open or short circuit of harness between pres-
sure sensor and ECM.

2Poor contact of pressure sensor connector and
ECM connector.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
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11. Diagnostics Chart with Trouble Code

OBD0691A
3CHECK INPUT SIGNAL FOR ECM. (USING
VOLTAGE METER AND SUBARU SELECT
MONITOR.)
1) Measure voltage between ECM and body.
: Connector & terminal
(B84) No. 22—Body/4.5 V, or more
: Go to next step.
: Go to next.
OBD0158
: Is the voltage more than 4.5 V while shaking
harness and connector of ECM?

Subaru Select Monitor
Designate mode using function key.
Function mode: F23

F23: Display shows voltage signal value sent from pres-
sure sensor.
: Repair poor contact in ECM connector.
: Replace ECM with a new one.
OBD0692A
2) Measure voltage between ECM and body.
: Connector & terminal
(B84) No. 23—Body/0.2 V, or less
: Go to next.
: Go to step 4.
OBD0158
: Is the voltage more than 0.2 V while shaking
harness and connector of ECM and monitor-
ing the value with Subaru select monitor?

Subaru Select Monitor
Designate mode using function key.
Function mode: F23

F23: Display shows voltage signal value sent from pres-
sure sensor.
: Repair poor contact in ECM connector.
: Go to step 4.
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11. Diagnostics Chart with Trouble Code

OBD0693A
4CHECK HARNESS CONNECTOR BETWEEN
ECM AND PRESSURE SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector pressure sensor.
3) Turn ignition switch to ON.
4) Measure voltage of harness connector between pres-
sure sensor and body.
: Connector & terminal
(B2) No. 3—Body/4.5 V, or more
: Repair open circuit of harness between ECM and
pressure sensor.
: Go to the next step.
OBD0694A
5) Turn ignition switch to OFF.
6) Disconnect connector from ECM.
7) Measure resistance of harness connector between
ECM and pressure sensor.
: Connector & terminal
(B84) No. 23—(B2) No. 2/10Ω, or less
(B84) No. 25—(B2) No. 1/10Ω, or less
: Repair open circuit of harness between ECM and
pressure sensor connector.
: Go to the next step.
OBD0695A
8) Measure resistance of the connector between pressure
sensor and body.
: Connector & terminal
(B2) No. 2—Body/500 kΩ, or more
: Repair short circuit of the harness between ECM
and pressure sensor connector.
: Go to the next.
: Is there poor contact in pressure sensor
connector?
: Repair poor contact in pressure sensor connector.
: Replace pressure sensor with a new one.
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11. Diagnostics Chart with Trouble Code

OBD0620
5CHECK HARNESS CONNECTOR BETWEEN
ECM AND PRESSURE SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from pressure sensor.
3) Turn ignition switch to ON.
4) Read data on Subaru select monitor or the OBD-II gen-
eral scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F24
: Is the value more than 4.9 V?
: Repair short circuit of harness between ECM and
pressure sensor connector.
: Replace pressure sensor with a new one.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
150
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11. Diagnostics Chart with Trouble Code

OBD0170
E: DTC P0106
—PRESSURE SENSOR CIRCUIT
RANGE/PERFORMANCE PROBLEM (P
—R)—
DESCRIPTION:
Refer to“D: DTC P0105—PRESSURE SENSOR CIR-
CUIT MALFUNCTION—[T11D0]”.
DTC DETECTING CONDITION:

Two consecutive trips with fault
1.Check transmission type.
AT
MT
Check AT/MT identification circuit.
2.Check DTC P0105 or P1102 on display.
No
Ye s

Inspect DTC P0105 or P1102 using“11. Diagnostics
Chart with Trouble Code [T1100]”.

In this case, it is unnecessary to inspect DTC
P0106.
3.Check data for control.
4.Check vacuum hose.
5.Check pressure sources of switching solenoid
valve.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. [T3D0] and [T3E0].>




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11. Diagnostics Chart with Trouble Code

OBD0620
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: F24 and F23

F24: Display shows a voltage signal value sent from the
pressure sensor.

F23: Display shows a voltage signal value sent from the
pressure sensor.
: Is the voltage more than 3.24 V with func-
tion mode F24?
: Go to step 4.
: Go to next.
OBD0158
: Is the voltage less than 1.6 V with function
mode F23?
: Go to step 5.
: Go to next.
OBD0158
: Is the voltage more than 4.7 V with function
mode F23?
: Replace pressure sensor.
: Repair poor contact in pressure sensor connector,
pressure sources switching solenoid valve
connector, and ECM connector.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
154
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11. Diagnostics Chart with Trouble Code

4
CHECK VACUUM HOSE.
: Check for disconnection, holes, or clogging
of the vacuum hoses.
NOTE:
Check the hoses;

From pressure sources switching solenoid valve to
intake manifold.

From pressure sensor to pressure sources switching
solenoid valve.
: Repair hoses.
: Go to step 5.
5CHECK PRESSURE SOURCES OF SWITCH-
ING SOLENOID VALVE.
1) Turn ignition switch to OFF.
2) Connect test mode connector.
3) Turn ignition switch to ON.
: Is operation sound of the pressure sources
solenoid valve heard? (ON↔OFF each 1.5
sec.)
: Replace pressure sensor.
: Replace pressure sources switching solenoid
valve.
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11. Diagnostics Chart with Trouble Code

OBD0172
F: DTC P0115
—ENGINE COOLANT TEMPERATURE
SENSOR CIRCUIT MALFUNCTION (TW)—
OBD0173A
DESCRIPTION:
The engine coolant temperature sensor is located on the
engine coolant pipe which is made of aluminum alloy. Its
thermistor changes resistance with respect to temperature.
A engine coolant temperature signal converted into resis-
tance is transmitted to the ECM to control the amount of
fuel injection, ignition timing, purge control solenoid valve,
etc.
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Hard to start

Erroneous idling

Poor driving performance
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code