check engine light SUBARU LEGACY 1996 Service Service Manual

6. Basic Diagnostics Procedure
Trouble occurs.
Ask the customer when and how the
trouble occurred using interview
check list.
Start the engine.
Ye sNoInspection using“8. Diagnostics for
Engine Start Failure 2-7 [T800]”.
Malfunction indicator lamp (MIL) illu-
minates.
Ye sNoInspection using“9. General Diag-
nostics Table 2-7 [T900]”.
Inspection using Subaru select moni-
tor or OBD-II general scan tool.
(Subaru select monitor: MODE FB1)
Trouble code
No trouble code designated.Repair.
See NOTE: *1
designated.
Inspection using“10. Diagnostics
Chart with Trouble Code 2-7
[T1000]”.
See NOTE: *2.
Trouble code
designated.

Repair.
Inspection mode
Inspection using Subaru select moni-
tor or OBD-II general scan tool.
(Subaru select monitor: MODE FB0)
No trouble code
Clear memory mode.
designated.
END
NOTE:
*1: If trouble code is not shown on display although the
MIL illuminates, perform diagnostics of the MIL (CHECK
ENGINE LIGHT) circuit or combination meter. Diagnostics for CHECK ENGINE Malfunction Indicator
Lamp (MIL) 2-7 [T700].”>
*2: Carry out the basic check, only when trouble code
about automatic transmission is shown on display. 2-7 [T601].>






75
2-7ON-BOARD DIAGNOSTICS II SYSTEM
6. Basic Diagnostics Procedure

2. CHECK LIST FOR INTERVIEW
Check the following items when problem occurred.
Customer’s name Engine no.
Date of sale Fuel brand
Date of repair Odometer readingkm
miles
Vin no.
WeatherFineCloudyRainySnowyVarious/Other
Outdoor TemperatureHotWarmCoolCold (approx.°F/°C)
PlaceHighwaySuburbsInner CityUphillDownhill
Rough roadOther
Engine Temp.ColdWarming-upAfter warming-upAny temp.Other
Engine speed
0 2,000 4,000 6,000 8,000 rpm
Driving conditionsNot affected
At startingWhile idlingAt racing
While acceleratingWhile cruising
While deceleratingWhile turning (RH/LH)
Vehicle speed
0 102030405060MPH
HeadlightON /OFF
BlowerON /OFF
A/C compressorON /OFF
Cooling fanON /OFF
Front wiperON /OFF
Rear wiperON /OFF
Rear defoggerON /OFF
RadioON /OFF
CD/CassetteON /OFF
Car phoneON /OFF
CB
NOTE: Use copies of this page for interviewing customers.
77
2-7ON-BOARD DIAGNOSTICS II SYSTEM
6. Basic Diagnostics Procedure

Check the following items about the vehicle’s state when
MIL turns on.
a) Other warning lights or indicators turn on.Ye s /No

1Low fuel warning light

2Charge indicator light

3AT diagnostics indicator light

4ABS warning light

5TCS warning light

6Engine oil pressure warning light
b) Fuel level

Lack of gasoline:Ye s /No

Indicator position of fuel gauge:
c) Intentional connecting or disconnecting of harness connectors or spark plug cords:Ye s /No

What:
d) Intentional connecting or disconnecting of hoses:Ye s /No

What:
e) Installing of parts other than genuine partsYe s /No

What:

Where:
f) Occurrence of noiseYe s /No

From where:

What kind:
g) Occurrence of smellYe s /No

From where:

What kind:
h) Intrusion of water into engine compartment or passenger compartmentYe s /No
i) Troubles occurred

1Engine does not start.

2Engine stalls during idling.

3Engine stalls while driving.

4Engine speed decreases.

5Engine speed does not decrease.

6Rough idling

7Poor acceleration

8Back fire

9After fire

10No shift

11Excessive shift shock
NOTE: Use copies of this page for interviewing customers.
78
2-7ON-BOARD DIAGNOSTICS II SYSTEM
6. Basic Diagnostics Procedure

B2M0244A
10AA3
CHECK KNOCK SENSOR.
1) Disconnect connector from knock sensor.
2) Measure resistance between knock sensor connector
terminal and engine ground.
: Terminal
No. 1—Engine ground:
Is the resistance less than 400 kΩ?
: Replace knock sensor.
: Repair short circuit in harness between knock
sensor connector and ECM connector.
NOTE:
The harness between both connectors is shielded. Repair
short circuit of harness together with shield.
B2M0561A
10AA4
CHECK INPUT SIGNAL FOR ECM.
1) Connect connectors to ECM and knock sensor.
2) Turn ignition switch to ON.
3) Measure voltage between ECM and chassis ground.
: Connector & terminal
(B84) No. 3 (+)—Chassis ground ():
Is the voltage more than 2 V?
: Even if MIL lights up, the circuit has returned to a
normal condition at this time. (However, the pos-
sibility of poor contact still remains.)
NOTE:
In this case, repair the following:

Poor contact in knock sensor connector

Poor contact in ECM connector

Poor contact in coupling connector (B21)
: Repair poor contact in ECM connector.
214
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

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

G3M0717
3. OPERATION OF SHIFT SELECTOR LEVER
WARNING:
Stop the engine while checking operation of selector
lever.
1) Check that selector lever does not move from“N”to“R”
without pushing the button.
2) Check that selector lever does not move from“R”to“P”
without pushing the button.
3) Check that selector lever does not move from“P”to“R”
without pushing the button.
4) Check that selector lever does not move from“3”to“2”
without pushing the button.
3. Electrical Components Location
1. SENSOR AND CONTROL MODULE
B3M0178B
1Throttle position sensor

2Dropping resistor

3Vehicle speed sensor 2

4Inhibitor switch

5ECM

6Vehicle speed sensor 1 (AWD)

7Vehicle speed sensor 1 (FWD)

8TCM
9Data link connector (for Subaru select monitor only)

10Data link connector (for Subaru select monitor and OBD-II
general scan tool)

11Diagnosis connector

12Diagnosis terminal

13AT OIL TEMP indicator light
(AT diagnostic indicator light)
3
3-2AUTOMATIC TRANSMISSION AND DIFFERENTIAL
2. Pre-inspection - 3. Electrical Components Location

G3M0717
3. OPERATION OF SHIFT SELECTOR LEVER
WARNING:
Stop the engine while checking operation of selector
lever.
1) Check that selector lever does not move from“N”to“R”
without pushing the button.
2) Check that selector lever does not move from“R”to“P”
without pushing the button.
3) Check that selector lever does not move from“P”to“R”
without pushing the button.
4) Check that selector lever does not move from“3”to“2”
without pushing the button.
3. Electrical Components Location
1. SENSOR AND CONTROL MODULE
B3M0178B
1Throttle position sensor

2Dropping resistor

3Vehicle speed sensor 2

4Inhibitor switch

5ECM

6Vehicle speed sensor 1 (AWD)

7Vehicle speed sensor 1 (FWD)

8TCM
9Data link connector (for Subaru select monitor only)

10Data link connector (for Subaru select monitor and OBD-II
general scan tool)

11Diagnosis connector

12Diagnosis terminal

13AT OIL TEMP indicator light
(AT diagnostic indicator light)
3
3-2AUTOMATIC TRANSMISSION AND DIFFERENTIAL
2. Pre-inspection - 3. Electrical Components Location

OBD0607A
4. CHECK OUTPUT SIGNAL EMITTED FROM TCM.
1) Connect connectors to TCM and transmission.
2) Lift-up the vehicle or set the vehicle on free roller.
CAUTION:
On AWD models, raise all wheels off floor.
3) Start and warm-up the engine and transmission.
4) Push the TCS OFF switch to ON. (With TCS models)
5) Move selector lever to“D”and slowly increase vehicle
speed to 75 km/h (47 MPH).
6) Measure voltage between TCM connector terminals.
Connector & terminal / Specified voltage:
(B55) No. 5—No. 10 / 8.5 V, or more (when
wheels are locked-up.)
OBD0607A
7) Return the engine to idling speed and move selector
lever to“N”.
8) Measure voltage between TCM connector terminals.
Connector & terminal / Specified voltage:
(B55) No. 5—No. 10 / 0.5 V, or less
NOTE:
The speed difference between front and rear wheels may
light either the ABS or the ABS/TCS warning light, but this
indicates no malfunctions. When AT control diagnosis is
finished, perform the ABS or the ABS/TCS memory clear-
ance procedure of self-diagnosis system.

OBD0145A

Using Subaru select monitor:
(1) Connect connectors to TCM and transmission.
(2) Lift-up the vehicle or set the vehicle on free roller.
CAUTION:
On AWD models, raise all wheels off floor.
(3) Turn ignition switch to OFF.
(4) Connect the Subaru select monitor to data link con-
nector.
(5) Turn ignition switch to ON and Subaru select moni-
tor switch to ON.
21
3-2AUTOMATIC TRANSMISSION AND DIFFERENTIAL
7. Diagnostic Chart with Trouble Code

OBD0455A
4) Measure resistance of harness connector between
TCM and body to make sure that circuit does not short.
Connector & terminal / Specified resistance:
(B55) No. 15—Body/1MΩ, or more
(B55) No. 10—Body/1MΩ, or more
G3M0109
2. CHECK SHIFT SOLENOID 3’s GROUND LINE.
Measure resistance between transmission connector
receptacle and transmission case.
Connector & terminal / Specified resistance:
(T4) No. 4—Transmission / 1Ω, or less
G3M0117
3. CHECK SHIFT SOLENOID 3.
Measure resistance between transmission connector
receptacle’s terminals.
Connector & terminal / Specified resistance:
(T4) No. 1—No.4/20—32Ω
B3M0381A
4. CHECK OUTPUT SIGNAL EMITTED FROM TCM.
1) Connect connectors to TCM and transmission.
2) Lift-up or raise the vehicle and support with safety
stands.
CAUTION:
On AWD models, raise all wheels off ground.
3) Start and warm-up the engine and transmission.
4) Idle the engine.
5) Move selector lever to“D”.
6) Measure voltage between TCM connector terminals.
Connector & terminal / Specified voltage:
(B55) No. 15—No. 10 / 9 V, or more
NOTE:
The speed difference between front and rear wheels may
light either the ABS or the ABS/TCS warning light, but this
indicates no malfunctions. When AT control diagnosis is
finished, perform the ABS or the ABS/TCS memory clear-
ance procedure of self-diagnosis system.

24
3-2AUTOMATIC TRANSMISSION AND DIFFERENTIAL
7. Diagnostic Chart with Trouble Code