1996 SUBARU LEGACY check engine

7. Diagnostics for CHECK ENGINE
Malfunction Indicator Lamp (MIL)
A: CHECK ENGINE MALFUNCTION
INDICATOR LAMP (MIL) DOES NOT COME
ON.
DIAGNOSIS:

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

When ignition switch is turned ON (engine OFF), MIL
does not come on.
7A1Check output signal from ECM.
7A2Check harness between combination meter
and ECM connector.
7A3Check harness between combination meter
and ignition switch connector.
WIRING DIAGRAM:
B2M0507


79
2-7ON-BOARD DIAGNOSTICS II SYSTEM
7. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

B2M0508A
7A1
CHECK OUTPUT SIGNAL FROM ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM connector and chassis
ground.
: Connector & terminal
(B84) No. 58 (+) — Chassis ground ():
Is the voltage less than 1 V?
: Go to step7A2.
: Go to next.
: Does the MIL come on when shaking or
pulling ECM connector and harness?
: Repair poor contact in ECM connector.
: Go to next.
: Is ECM connector correctly connected?
: Replace ECM.
: Repair connection of ECM connector.
B2M0763A
7A2CHECK HARNESS BETWEEN COMBINA-
TION METER AND ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Remove combination meter.
3) Disconnect connector from ECM and combination
meter.
4) Measure resistance of harness between ECM and com-
bination meter connector.
: Connector & terminal
(B84) No. 58 — (i14) No. 2:
Is resistance less than 1Ω?
: Go to next.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between ECM and combination
meter connector

Poor contact in coupling connector (B37)
: Is there poor contact in combination meter
connector?
: Repair poor contact in combination meter connec-
tor.
: Go to step7A3.
80
2-7ON-BOARD DIAGNOSTICS II SYSTEM
7. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

B2M0510A
7A3CHECK HARNESS BETWEEN COMBINA-
TION METER AND IGNITION SWITCH
CONNECTOR.
1) Turn ignition switch to ON.
2) Measure voltage between combination meter connector
and chassis ground.
: Connector & terminal
(i14) No. 11 (+)—Chassis ground ():
Is voltage more than 10 V?
: Go to next.
: Check the following and repair if necessary.

Blown out fuse (No. 15).
NOTE:
If replaced fuse (No. 15) blows easily, check the harness
for short circuit of harness between fuse (No. 15) and com-
bination meter connector.

Open or short circuit in harness between fuse (No. 15)
and combination meter connector

Open or short circuit in harness between fuse (No. 15)
and ignition switch connector

Poor contact in ignition switch connector
: Is there poor contact in combination meter
connector?
: Repair poor contact in combination meter connec-
tor.
: Replace bulb or combination meter.
81
2-7ON-BOARD DIAGNOSTICS II SYSTEM
7. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

B: CHECK ENGINE MALFUNCTION
INDICATOR LAMP (MIL) DOES NOT GO OFF.
DIAGNOSIS:

The CHECK ENGINE malfunction indicator lamp (MIL)
circuit is shorted.
TROUBLE SYMPTOM:

Although MIL comes on when engine runs, trouble code
is not shown on Subaru select monitor or OBD-II general
scan tool display.
7B1Check harness between combination meter
and ECM connector.
WIRING DIAGRAM:
B2M0507
B2M0470C
7B1CHECK HARNESS BETWEEN COMBINA-
TION METER AND ECM CONNECTOR.
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 in harness between combina-
tion meter and ECM connector.
: Replace ECM.
82
2-7ON-BOARD DIAGNOSTICS II SYSTEM
7. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

C: CHECK ENGINE MALFUNCTION
INDICATOR LAMP (MIL) DOES NOT BLINK AT
A CYCLE OF 3 HZ.
DIAGNOSIS:

The CHECK ENGINE malfunction indicator lamp (MIL)
circuit is open or shorted.

Test mode connector circuit is in open.
TROUBLE SYMPTOM:

When inspection mode, MIL does not blink at a cycle of
3 Hz.
7C1Check operation of CHECK ENGINE
malfunction indicator lamp (MIL).
7C2Check output signal from ECM.

7C3Check harness between ECM and test mode
connector.
7C4Check ground circuit.
WIRING DIAGRAM:
B2M0511


83
2-7ON-BOARD DIAGNOSTICS II SYSTEM
7. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

B2M0470C
7C1CHECK OPERATION OF CHECK ENGINE
MALFUNCTION INDICATOR LAMP (MIL).
1) Turn ignition switch to OFF.
2) Disconnect test mode connector.
3) Turn ignition switch to ON.
: Does the MIL come on?
: Go to step7C2.
: Repair the MIL circuit.
B2M0512A
7C2
CHECK OUTPUT SIGNAL FROM ECM.
Measure voltage between test mode connector and chas-
sis ground.
: Connector & terminal
(B75) No.1 (+)—Chassis ground ():
Is voltage less than 1 V?
: Go to step7C3.
: Go to step7C4.
B2M0513A
7C3CHECK HARNESS BETWEEN ECM AND
TEST MODE CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between ECM and test
mode connector.
: Connector & terminal
(B84) No.84—(B75) No.1:
Is resistance less than 1Ω?
: Go to next.
: Repair open circuit in harness between ECM and
test mode connector.
: Is there poor contact in ECM connector?
: Repair poor contact in ECM connector.
: Replace ECM.
84
2-7ON-BOARD DIAGNOSTICS II SYSTEM
7. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

B2M0514A
7C4
CHECK GROUND CIRCUIT.
1) Turn ignition switch to OFF.
2) Measure resistance of harness between test mode con-
nector and chassis ground.
: Connector & terminal
(B76) No.1—Chassis ground:
Is resistance less than 5Ω?
: Repair poor contact in test mode connector.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between test mode and coupling
connector (B22)

Open circuit in harness between coupling connector
(B22) and engine grounding terminal

Poor contact in coupling connector (B22)
85
2-7ON-BOARD DIAGNOSTICS II SYSTEM
7. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)

D: CHECK ENGINE MALFUNCTION
INDICATOR LAMP (MIL) REMAINS BLINKING
AT A CYCLE OF 3 Hz.
DIAGNOSIS:

Test mode connector circuit is shorted.
TROUBLE SYMPTOM:

Even though test mode connector is disconnected, MIL
blinks at a cycle of 3 Hz when ignition switch is turned to
ON.
7D1Check harness between ECM connector and
engine grounding terminal.
WIRING DIAGRAM:
B2M0511
86
2-7ON-BOARD DIAGNOSTICS II SYSTEM
7. Diagnostics for CHECK ENGINE Malfunction Indicator Lamp (MIL)