check engine SUBARU LEGACY 1996 Service Repair Manual

B2M0578A
10AN4CHECK POWER SUPPLY TO IDLE AIR
CONTROL SOLENOID VALVE.
1) Turn ignition switch to OFF.
2) Disconnect connector from idle air control solenoid
valve.
3) Turn ignition switch to ON.
4) Measure voltage between idle air control solenoid valve
and engine ground.
: Connector & terminal
(E7) No. 2 (+)—Engine ground ():
Is the voltage more than 10 V?
: Go to step10AN5.
: Repair open circuit in harness between idle air
control solenoid valve and main relay connector.
B2M0579A
10AN5CHECK HARNESS BETWEEN ECM AND
IDLE AIR CONTROL SOLENOID VALVE
CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between ECM and idle
air control solenoid valve connector.
: Connector & terminal
(B84) No. 14—(E7) No. 1:
Is the resistance less than 1Ω?
: Go to next.
: Repair open circuit in harness between ECM and
idle air control solenoid valve connector.
: Connector & terminal
(B84) No. 13—(E7) No. 3:
Is the resistance less than 1Ω?
: Go to next step 4).
: Repair open circuit in harness between ECM and
idle air control solenoid valve connector.
B2M0580A
4) Measure resistance of harness between ECM and
chassis ground.
: Connector & terminal
(B84) No. 13—Chassis ground:
Is the resistance less than 10Ω?
: Repair short circuit in harness between ECM and
idle air control solenoid valve connector.
: Go to next.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0370
AO: DTC P0506
—IDLE CONTROL SYSTEM RPM LOWER
THAN EXPECTED (ISC
—L)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Engine is difficult to start.

Engine does not start.

Erroneous idling

Engine stalls.
10AO1Check DTC P0505 on display.
10AO2Check air intake system.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

10AO1
CHECK DTC P0505 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0505?
: Inspect DTC P0505 using“10. Diagnostics Chart
with Trouble Code 2-7 [T1000]”.
NOTE:
In this case, it is not necessary to inspect DTC P0506.
: Go to step10AO2.
10AO2
CHECK AIR INTAKE SYSTEM.
1) Turn ignition switch to ON.
2) Start engine, and idle it.
: Is clogging the by-pass line between by-
pass hose and intake duct?
: Repair the by-pass line.
: Replace idle air control solenoid valve.

276
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0371
AP: DTC P0507
—IDLE CONTROL SYSTEM RPM HIGHER
THAN EXPECTED (ISC
—H)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Engine keeps running at higher revolution than specified
idling revolution.
10AP1Check DTC P0505 on display.
10AP2Check air intake system.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

10AP1
CHECK DTC P0505 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0505?
: Inspect DTC P0505 using“10. Diagnostics Chart
with Trouble Code 2-7 [T1000]”.
NOTE:
In this case, it is not necessary to inspect DTC P0507.
: Go to step10AP2.
10AP2
CHECK AIR INTAKE SYSTEM.
1) Turn ignition switch to ON.
2) Start engine, and idle it.
: Is there a fault in air intake system?
NOTE:
Check the following items.

Loose installation of intake manifold, idle air control sole-
noid valve and throttle body

Cracks of intake manifold gasket, idle air control sole-
noid valve gasket and throttle body gasket

Loose connections and cracks of idle air control solenoid
valve by-pass hoses

Disconnections of vacuum hoses
: Repair air suction and leaks.
: Replace idle air control solenoid valve.

277
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0376
AR: DTC P0601
—INTERNAL CONTROL MODULE MEMORY
CHECK SUM ERROR (RAM)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Engine does not start.

Engine stalls.
10AR1Check DTC P0601 on display.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:

LHD Model
B2M0519
281
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

B2M0656
AT: DTC P0705
—TRANSMISSION RANGE SENSOR CIRCUIT
MALFUNCTION (ATRNG)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Starter does not rotate when selector lever is in“P”or
“N”range.

Starter rotates when selector lever is in“R”,“D”,“3”,“2”
or“1”range.

Engine brake is not effected when selector lever is in“3”
range.

Shift characteristics are erroneous.
10AT1Check harness between TCM and inhibitor
switch connector.
10AT2Check inhibitor switch.
10AT3Check input signal for TCM.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.



286
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0380
AU: DTC P0710
—TRANSMISSION FLUID TEMPERATURE
SENSOR CIRCUIT MALFUNCTION (ATF)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

No shift up to 4th speed (after engine warm-up)

No lock-up (after engine warm-up)

Excessive shift shock
10AU1Check DTC P0710 on display.
Check ATF temperature sensor circuit.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:
OBD0383
10AU1
CHECK DTC P0710 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0710?
: Check ATF temperature sensor circuit.
NOTE:
For the diagnostic procedure on transmission fluid tem-
perature sensor circuit, refer to 3-2 [T7F0].

293
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0404
AW: DTC P0725
—ENGINE SPEED INPUT CIRCUIT
MALFUNCTION (ATNE)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

No lock-up (after engine warm-up)

AT diagnostic indicator light (AT OIL TEMP indicator
light) remains on when vehicle speed is“0”.
10AW1Check DTC P0725 on display.
Check engine speed input signal circuit.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:
B2M0585
10AW1
CHECK DTC P0725 ON DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0725?
: Check engine speed input signal circuit.
NOTE:
For the diagnostic procedure on engine speed input circuit,
refer to 3-2 [T7H0].

295
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

10BA1Check any other DTC (besides DTC P0731,
P0732, P0733, P0734) on display.
10BA2Check throttle position sensor circuit. 3-2 [T7K0].>
10BA3Check vehicle speed sensor 1 circuit. 3-2 [T7L0].>
10BA4Check vehicle speed sensor 2 circuit. 3-2 [T7M0].>
10BA5Check engine speed input circuit.

CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.





297
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

10BA2CHECK THROTTLE POSITION SENSOR
CIRCUIT.
: Is there any trouble in throttle position sen-
sor circuit?
NOTE:
For the diagnostic procedure on throttle position sensor
circuit, refer to 3-2 [T7K0].
: Repair or replace throttle position sensor circuit.
: Go to step10BA3.
10BA3CHECK VEHICLE SPEED SENSOR 1 CIR-
CUIT.
: Is there any trouble in vehicle speed sensor
1 circuit?
NOTE:
For the diagnostic procedure on vehicle speed sensor 1
circuit, refer to 3-2 [T7L0].
: Repair or replace vehicle speed sensor 1 circuit.
: Go to step10BA4.
10BA4CHECK VEHICLE SPEED SENSOR 2 CIR-
CUIT.
: Is there any trouble in vehicle speed sensor
2 circuit?
NOTE:
For the diagnostic procedure on vehicle speed sensor 2
circuit, refer to 3-2 [T7M0].
: Repair or replace vehicle speed sensor 2 circuit.
: Go to step10BA5.
10BA5
CHECK ENGINE SPEED INPUT CIRCUIT.
: Is there any trouble in engine speed input
circuit?
NOTE:
For the diagnostic procedure on engine speed input signal
circuit, refer to 3-2 [T7H0].
: Repair or replace engine speed input circuit.
: Go to next.
: Is there poor contact in TCM connector?
: Repair poor contact in TCM connector.
: Go to next.
: Is there any mechanical trouble in automatic
transmission?
: Repair or replace automatic transmission.
: Replace TCM.
299
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

B2M0661
BB: DTC P0740
—TORQUE CONVERTER CLUTCH SYSTEM
MALFUNCTION (ATLU
—F)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

No lock-up (after engine warm-up)

No shift or excessive tight corner“braking”
10BB1Check any other DTC (besides DTC P0740) on
display.
10BB2Check duty solenoid B circuit. [T7B0].>
10BB3Check throttle position sensor circuit. 3-2 [T7K0].>
10BB4Check vehicle speed sensor 1 circuit. 3-2 [T7L0].>
10BB5Check vehicle speed sensor 2 circuit. 3-2 [T7M0].>
10BB6Check engine speed input circuit. [T7H0].>
10BB7Check inhibitor switch circuit. DTC P0705, 2-7 [T10AT0].>
10BB8Check brake light switch circuit. DTC P0703, 2-7 [T10AS0].>
10BB9Check ATF temperature sensor circuit. 3-2 [T7F0].>
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.









300
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code