1996 SUBARU LEGACY Ecu

C: CONTROL MODULE I/O SIGNAL
B6M0405
Content Terminal No.Measuring conditions and I/O signals
(Ignition switch ACC position)
Door lock/unlock switch1
(INPUT)
Battery voltage is present when all doors and rear gate (WAGON) are locked.

“0”volt is present when one of the doors or rear gate (WAGON) is unlocked.
Key cylinder lock switch2
(INPUT)
“0”volt is present when key cylinder is turned to LOCK position.

Battery voltage is present when key cylinder is in positions other than LOCK.
Tamper switch3
(INPUT)
Battery voltage is present when key cylinder switch is installed to key cylinder.

“0”volt is present when key cylinder switch is removed from key cylinder.
Door switch4
(INPUT)
Battery voltage is present when all doors are closed.

“0”volt is present when one of the doors is open.
Starter interrupt relay5
(OUTPUT)
Battery voltage is present when ignition switch is turned ACC or ON.

“0”volt is present when security system is in alarm state.
Ignition switch (ACC)6
(INPUT)
Battery voltage is present when ignition switch is turned ACC or ON.

“0”volt is present when ignition switch is turned OFF.
Security indicator light7
(OUTPUT)
Battery voltage is present when indicator light goes off.

“0”volt is present when indicator light illuminates.
Power supply (back-up) 8 Battery voltage is constantly present.
Ground 9—
Engine hood switch10
(INPUT)
Battery voltage is present when engine hood is closed.

“0”volt is present when engine hood is open.
Trunk lid switch (SEDAN)
Rear gate switch (WAGON)11
(INPUT)
Battery voltage is present when trunk lid or rear gate is closed.

“0”volt is present when trunk lid or rear gate is open.
Headlight alarm relay12
(OUTPUT)
Battery voltage is present when ignition switch is turned ACC or ON.

“0”volt and battery voltage repeats in alarm state. (Headlights flash intermittently
at 0.2 sec. ON and 0.6 sec. OFF intervals).
Horn relay13
(OUTPUT)
Battery voltage is present when ignition switch is turned ACC or ON.

“0”volt and battery voltage repeats in alarm state. (Horn sounds intermittently at
0.2 sec. ON and 0.6 sec. OFF intervals.)
Key cylinder unlock switch14
(INPUT)
“0”volt is present when key cylinder is turned to UNLOCK position.

Battery voltage is present when key cylinder is in positions other than UNLOCK.
Trunk lid key cylinder unlock
switch (SEDAN)15
(INPUT)
“0”volt is present when trunk lid key cylinder is turned to UNLOCK position.

Battery voltage is present when trunk lid key cylinder is in positions other than
UNLOCK.
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6. Security System

D: BASIC DIAGNOSTICS PROCEDURE
Start security system check.
Fully open all door windows and turn ignition switch OFF.
Take key out of ignition, exit vehicle and lock driver’s door.
Indicator light illuminates.
OK The light flashes.
 The light does not
illuminate.
Check indicator harness.
Check security indicator light.
Check driver’s door key cylinder lock/unlock switch.
Check security control module.
Check whether switch input signal remains UNLOCK.
Check wiring harness.
Check switch input signals.
(Harnesses and switches separately)
(Tamper, door, hood, trunk and rear gate
switch)Check security control module.
Wait for 30 seconds.
Indicator light flashes at long intervals (0.2 sec. ON and 2.4 sec.
OFF).
OK
 Not OK
Check security control module.
Unlock driver’s door using the inside lock knob and open door.
The horn sounds and headlights flash intermittently at 0.2 sec. ON
and 0.6 sec. OFF intervals.
The engine will not start even if the ignition switch is turned to
START. Indicator lamp goes out.
OK Starter motor runs.
 All are not OK.
Check driver’s door switch.
Check wiring harness.
Check security control module.
 Horn is not OK.
Check horn
operation by
pushing horn pad
on steering wheel.
OK
 Not OK
Check horn.
Check horn relay.
Check security control module.
Check harness between horn relay and security control module.
 Headlights are not
OK.
Check headlights
operation by
turning light switch
ON/OFF.
OK
 Not OK
Check headlight
bulbs.
Check combination
switch.
Check headlight
relay.
Check starter interrupt relay.
Check wiring harness.
Check security control module.Check headlight alarm relay.
Check security control module.
Check wiring harness.
The alarm system continues to operate for 150 seconds.
OK Not OK
The horn and
headlights turn off.
The starter motor
does not run.
OK
 Not OK
Check security
control module.
Unlock the driver’s door using ignition key.
Continues to next step.














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6. Security System

From the previous step
Starter motor runs.
OK
 Not OK
Check starter interrupt relay.
Check wiring harness.
Check security control module.
Check driver’s door unlock switch.
Lock the driver’s door without using a ignition key. (Set the inside
lock knob to LOCK and then close the door while lifting the outer
handle).
Within 30 seconds after the above step, open rear LH door.
Indicator light flashes with short intervals (1 Hz).
OK
 Not OK
Check rear LH door switch.
Check rear LH door switch harness.
Check security control module.
Close and lock door.
Indicator light illuminates continuously.
OK
Perform the above steps also on the rear RH door and front RH
door.
OK
 Not OK
Check rear and front RH door switches.
Check wiring harnesses.
Check security control module.
Pull engine hood opener lever and open engine hood.
Indicator light flashes at short intervals (1 Hz).
OK
 Not OK
Check hood switch.
Check hood switch harness.
Check security control module.
Close engine hood.
Indicator light illuminates continuously.
SEDAN
 WAGON
Unlock rear gate by operating driver’s door inside lock knob and
open rear gate.
Pull trunk opener lever and open trunk lid.Indicator light flashes at short intervals (1 Hz).
OK Not OK
Indicator light flashes at short intervals (1 Hz).
OK Not OKCheck rear gate switch.
Check rear gate switch harness.
Check security control module.
Check trunk switch.
Check trunk switch harness.
Check security control module.Close rear gate and lock by locking driver’s door using a
ignition key.
Close trunk lid.Indicator light illuminates continuously.
Indicator light illuminates continuously.Wait for 30 seconds.
Wait for 30 seconds.Indicator light flashes at long intervals (0.2 sec. ON and 2.4
sec. OFF).
Continues to next step. Continues to next step.


















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6. Security System

From the previous step. From the previous step.
Indicator light flashes at long intervals (0.2 sec. ON and 2.4 sec.
OFF).
Unlock rear gate using a ignition key and open.
Unlock trunk lid using a ignition key and open.
The alarm system does not operate.
OK Not OKThe alarm system does not operate.OK Not OK
Check trunk unlock switch.
Check trunk unlock switch harness.
Check security control module.
Check rear gate unlock switch.
Check rear gate unlock switch harness.
Check security control module.
Close trunk lid.Close rear gate.
Lock rear gate using a ignition key.
Indicator light illuminates continuously.Indicator light illuminates continuously.
OK Not OK
Check rear gate lock switch.
Check rear gate lock switch harness.
Check security control module.
Wait for 30 seconds.
Indicator light flashes at long intervals (0.2 sec. ON and 2.4 sec.
OFF).
Unlock front RH door using a ignition key and open.
The alarm system does not operate.
OK
 Not OK
Check front RH door key cylinder unlock switch.
Check front RH door key cylinder unlock switch harness.
Check security control module.
Close front RH door and lock using a ignition key.
Indicator light illuminates continuously.
OK
 Not OK
Check front RH door key cylinder lock switch.
Check front RH door key cylinder lock switch harness.
Check security control module.
Finish checking security system.
















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6. Security System

E: DIAGNOSTICS PROCEDURE FOR
SECURITY CONTROL MODULE POWER
SUPPLY/GROUND CIRCUIT
1. Check fuse and power supply circuit.
OK
Not OK

Replace fuse.

Repair or replace wiring harness.
2. Check ground circuit between security control
module and body.
OK
Not OK
Repair or replace wiring harness.
Go to next step on basic diagnostics procedure.

B6M0504A
1. CHECK FUSE AND POWER SUPPLY CIRCUIT.
1) Check fuse No. 25.
2) Measure voltage between main fuse box connector and
body.
Connector & terminal / Specified voltage:
(F35) No. 2—Body / 10 V, or more
B6M0448A
3) Disconnect connector from security control module.
4) Measure voltage between security control module con-
nector and body.
Connector & terminal / Specified voltage:
(B93) No. 8—Body / 10 V, or more
B6M0505A
5) Check fuse No. 3.
6) Turn ignition switch to ACC.
7) Measure voltage between fuse and relay box connec-
tor and body.
Connector & terminal / Specified voltage:
(i5) No. 13—Body / 10 V, or more


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6. Security System

B6M0452A
8) Disconnect connector from security control module.
9) Measure voltage between security control module con-
nector and body.
Connector & terminal / Specified voltage:
(B93) No. 6—Body / 10 V, or more
B6M0497A
2. CHECK GROUND CIRCUIT BETWEEN SECURITY
CONTROL MODULE AND BODY.
1) Turn ignition switch to OFF.
2) Disconnect connector of security control module.
3) Measure resistance of harness connector between
security control module and body.
Connector & terminal / Specified resistance:
(B93) No. 9—Body / 10Ω, max.
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6-2DIAGNOSTICS
6. Security System

F: DIAGNOSTICS PROCEDURE FOR
SECURITY INDICATOR LIGHT AND
INDICATOR LIGHT CIRCUIT
1. Check security indicator light.
OK
Not OK
Replace indicator light.
2. Check power supply for indicator light.
OK
Not OK
Repair or replace wiring harness.
3. Check harness connector between security
indicator light and security control module.
OK
Not OK
Repair or replace wiring harness.
Go to next step on basic diagnostics procedure.

B6M0382A
1. CHECK SECURITY INDICATOR LIGHT.
1) Remove security indicator light.
2) Measure resistance between security indicator light
connector terminals.
Terminals / Specified resistance:
No. 2—No. 4 / Approx. 120Ω
B6M0443A
2. CHECK POWER SUPPLY FOR INDICATOR LIGHT.
1) Disconnect connector of security indicator light.
2) Measure voltage between security indicator light con-
nector and body.
Connector & terminal / Specified voltage:
(i8) No. 2—Body / 10 V, or more
B6M0498A
3. CHECK HARNESS CONNECTOR BETWEEN
SECURITY INDICATOR LIGHT AND SECURITY
CONTROL MODULE.
1) Disconnect connectors of security indicator light and
security control module.
2) Measure resistance of harness connector between
security indicator light and security control module.
Connector & terminal / Specified resistance:
(i8) No. 4—(B93) No.7/10Ω, max.



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6. Security System

G: DIAGNOSTICS PROCEDURE FOR DOOR
SWITCH SIGNAL
1. Check door switch input signal for security
control module.
Not OK
OK
Go to next step on basic diagnostics procedure.

2. Check door switch.
OK
Not OK
Replace door switch.
Repair or replace wiring harness between door
switch and security control module.
B6M0453A
1. CHECK DOOR SWITCH INPUT SIGNAL FOR
SECURITY CONTROL MODULE.
1) Remove security control module without disconnecting
connector.
2) Turn door switch ON/OFF and measure voltage
between security control module connector and body.
Connector & terminal / Specified voltage:
(B93) No. 4—Body / 10 V, or more (Door closed)
/ 1 V, max. (Door opened)
NOTE:
When one of the doors is open, the voltage may be 1 V,
max.
2. CHECK DOOR SWITCH.
Refer to 6-2 [W8B1] for inspection of door switch.
NOTE:
The door switch is used for interior light also.


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6. Security System