check engine SUBARU LEGACY 1995 Service Repair Manual

8. Diagnostics for CHECK ENGINE
Malfunction Indicator Lamp (MIL)
DIAGNOSIS:

The CHECK ENGINE malfunction indicator lamp (MIL)
circuit is in short or open.
TROUBLE SYMPTOM:

When ignition switch is turned to ON (engine OFF), MIL
does not illuminate.....TROUBLE SYMPTOM 1

Although MIL illuminates, trouble code is not shown on
Subaru select monitor or the OBD-II general scan tool dis-
play.....TROUBLE SYMPTOM 2
1.Classify the malfunction. Is it a TROUBLE
SYMPTOM 1 or TROUBLE SYMPTOM 2?
TROUBLE SYMPTOM 2

TROUBLE
SYMPTOM 1
2.Check output signal from ECM.
4.Check short circuit of harness.3.Check harness connector between ECM and
ignition switch.
WIRING DIAGRAM:
OBD0094

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2-7ON-BOARD DIAGNOSTICS II SYSTEM
8. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

1CLASSIFY THE MALFUNCTION. IS IT A
TROUBLE SYMPTOM 1 OR TROUBLE SYMP-
TOM 2?
If the malfunction shows TROUBLE SYMPTOM 1, go to
step 2.
If the malfunction shows TROUBLE SYMPTOM 2, go to
step 4.
OBD0095A
2
CHECK OUTPUT SIGNAL FROM ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM and body.
: Connector & terminal
(B84) No. 31 — Body/1 V, or less
: Go to step 3.
:
If MIL comes on when shaking or pulling ECM
connector and harness, repair ECM connector.

Check that ECM connector is correctly con-
nected. If the MIL does not come on even when
ECM connector is correctly connected, replace
the ECM.
OBD0096
3CHECK HARNESS CONNECTOR BETWEEN
ECM AND IGNITION SWITCH.
Check the following and repair if necessary.

1Check that fuse (No. 15) is not blown out.
NOTE:
If replaced fuse (No. 15) blows out easily, check the har-
ness for short circuit between fuse (No. 15) and combina-
tion meter.

2Check that harness from fuse to combination meter is
not open.

3Check that the MIL wiring is not open.

4Check that harness from combination meter to the ECM
is not open.

5Check that the connector (B37) is correctly connected
as the wiring diagram shows.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
8. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

4
CHECK SHORT CIRCUIT OF HARNESS.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Turn ignition switch to ON.
: Does the MIL come on?
: Repair short circuit of harness between ECM and
combination meter.
: Replace ECM.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
8. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

B: STARTER MOTOR CIRCUIT
1.Check input signal for starter motor.2.Check ground circuit of starter motor.
3.Check harness connector between battery and
ignition switch.
4.

Check inhibitor switch. (AT vehicles only)

Check starter interlock circuit. (MT vehicles
only)
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. [T3D0] and [T3E0].>
WIRING DIAGRAM:
B2M0621


108
2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. Diagnostics for Engine Starting Failure

OBD0724
1CHECK INPUT SIGNAL FOR STARTER
MOTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from starter motor.
3) Turn ignition switch to ST.
OBD0100A
4) Measure power supply voltage between starter motor
connector terminal and body.
: Connector & terminal
(B14) No. 1—Body/10 V, or more
NOTE:

On AT vehicles, place the inhibitor switch in the“P”or“N”
position.

On MT vehicles, depress the clutch pedal.
: Go to step 2.
: Go to step 3.
OBD0725
2CHECK GROUND CIRCUIT OF STARTER
MOTOR.
1) Turn ignition switch to OFF.
2) Disconnect terminal from starter motor.
3) Measure resistance of ground cable between ground
cable terminal and body.
: Is resistance less than 10Ω?
: Check starter motor.
: Repair open circuit of ground cable.
3CHECK HARNESS CONNECTOR BETWEEN
BATTERY AND IGNITION SWITCH.
1) Turn ignition switch to OFF.
2) Remove SBF No. 4 from main fuse box.
3) Measure resistance of fuse.
: Is resistance less than 1Ω?
: Replace SBF No. 4.
: Go to next step.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. Diagnostics for Engine Starting Failure

4) Install SBF No. 4 to main fuse box.
5) Turn ignition switch to ON.
OBD0103A
6) Measure power supply voltage between ignition switch
connector and body.
: Connector & terminal
(B72) No. 1—Body/10 V, or more
: Go to step 4.
: Repair harness between ignition switch connector
and body.
OBD0726A
4
CHECK INHIBITOR SWITCH. (AT VEHICLES
ONLY)
1) Turn ignition switch to OFF.
2) Disconnect connector from transmission.
3) Measure resistance between transmission harness
connector receptacle’s terminals.
: Connector & terminal
(T3) No. 11—No. 12/10Ω, or less
: Repair harness between starter motor and ignition
switch connector.
: Repair or replace inhibitor switch.
OBD0654A
4
CHECK STARTER INTERLOCK CIRCUIT.
(MT VEHICLES ONLY)
1) Turn ignition switch to“ST”.
2) Measure voltage between clutch switch connector and
body.
: Connector & terminal
(B107) No. 2—Body/10 V, or more
: Replace starter interlock relay.
: Go to next step.
11 0
2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. Diagnostics for Engine Starting Failure

C: CONTROL MODULE POWER SUPPLY AND
GROUND LINE
1.Check main relay.
2.Check power supply circuit of ECM.
3.Check ground circuit of ECM.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. [T3D0] and [T3E0].>
WIRING DIAGRAM:

LHD model
OBD0105


11 2
2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. Diagnostics for Engine Starting Failure

G2M0444
1
CHECK MAIN RELAY.
1) Turn the ignition switch to OFF.
2) Remove main relay.
3) Connect battery to main relay terminals No. 1 and No.
2.
4) Measure resistance between main relay terminals.
: Terminals
No. 3—No. 5/10Ω, or less
No. 4—No. 6/10Ω, or less
: Go to step 2.
: Replace main relay.
OBD0107A
2
CHECK POWER SUPPLY CIRCUIT OF ECM.
1) Install main relay.
2) Disconnect connectors from ECM.
3) Turn ignition switch to ON.
4) Measure power supply voltage between ECM connec-
tor terminals.
: Connector & terminal
(B84) No. 15—No. 96/10 V, or more
(B84) No. 16—No. 96/10 V, or more
(B84) No. 42—No. 96/10 V, or more
: Go to step 3.
: Repair harness of power supply circuit.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. Diagnostics for Engine Starting Failure

OBD0108A
3
CHECK GROUND CIRCUIT OF ECM.
1) Turn ignition switch to OFF.
2) Measure resistance of harness connector between
ECM and body.
: Connector & terminal
(B84) No. 25—Body/10Ω, or less
(B84) No. 45—Body/10Ω, or less
(B84) No. 46—Body/10Ω, or less
(B84) No. 69—Body/10Ω, or less
(B84) No. 70—Body/10Ω, or less
(B84) No. 71—Body/10Ω, or less
(B84) No. 72—Body/10Ω, or less
(B84) No. 95—Body/10Ω, or less
(B84) No. 96—Body/10Ω, or less
: Check ignition control system. [T9D0]”.>
: Repair harness between ECM connector and
body.
11 5
2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. Diagnostics for Engine Starting Failure

D: IGNITION CONTROL SYSTEM
1.Check ignition system for sparks.
2.Check power supply circuit for ignition coil.
3.Check ignition coil.
4.Check harness connector between ignitor and
ignition coil.
5.Check input signal for ignitor.
6.Check harness connector of ignitor ground
circuit.
7.Check harness connector between ECM and
ignitor.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES. [T3D0] and [T3E0].>
WIRING DIAGRAM:
B2M0622






11 6
2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. Diagnostics for Engine Starting Failure