Subaru Legacy III (2000-2003 year). Service manual — part 1007

IM-12

IMMOBILIZER (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE FOR IMMOBILIZER INDICATOR LIGHT

Step

Value

Yes

No

1

CHECK IMMOBILIZER INDICATOR LIGHT
COMES ON.
1) Turn ignition switch OFF.
2) Disconnect harness connector from IMM

ECM.

3) Connect a resistor (750

Ω

) between IMM

ECM harness connector terminal No. 9 and
chassis ground.
Does indicator light comes on?

Indicator light comes on.

Go to step 2.

Go to step 5.

2

CHECK IMM ECM GROUND CIRCUIT.
Measure resistance between IMM ECM har-
ness connector terminal and chassis ground.

Connector & terminal

(B141) No. 2, No. 3 — Chassis ground:

Is the measured value less than the specified
value?

10

Ω

Go to step 3.

Repair open circuit
of IMM ECM
ground circuit.

3

CHECK IMM ECM IGNITION CIRCUIT.
1) Turn ignition switch ON. (Engine OFF.)
2) Measure voltage between IMM ECM har-

ness connector terminal and chassis
ground.

Connector & terminal

(B141) No. 12 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 4.

Check harness for
open or short
between IMM
ECM and ignition
switch.

4

CHECK IMM ECM POWER SUPPLY CIR-
CUIT.
1) Turn ignition switch OFF.
2) Measure voltage between IMM ECM har-

ness connector terminal and chassis
ground.

Connector & terminal

(B141) No. 10, No. 11 (+) — Chassis
ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Replace IMM ECM
<Ref. to SL-36,
Immobilizer Con-
trol Module.>and
then replace all
ignition keys
(including the tran-
sponder). Then
perform teaching
operation. Refer to
teaching opera-
tion manual (Pub.
No. S0820GZ).

Check harness for
open or short
between IMM
ECM and fuse.

5

CHECK COMBINATION METER CIRCUIT.
1) Remove combination meter. <Ref. to IDI-

14, REMOVAL, Combination Meter Assem-
bly.>

2) Measure voltage between combination

meter harness connector terminal and
chassis ground.

Connector & terminal

H4 non-TURBO model

(i12) No. 7 (+) — Chassis ground (

−−−−

):

H6 and H4 TURBO model

(i10) No. 9 (+) — Chassis ground (

−−−−

):

(i12) No. 1 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 6.

Check harness for
open or short
between combina-
tion meter and
fuse.

IM-13

IMMOBILIZER (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE FOR IMMOBILIZER INDICATOR LIGHT

6

CHECK COMBINATION METER CIRCUIT.
Measure resistance between IMM ECM har-
ness connector terminal and combination
meter harness connector terminal.

Connector & terminal

H4 non-TURBO model

(B141) No. 9 — (i12) No. 1:

LHD H6 model

(B141) No. 9 — (i10) No. 13:

RHD H6 and H4 TURBO models

(B141) No. 9 — (i10) No. 7:

Is the measured value less than the specified
value?

10

Ω

Faulty LED bulb.
Replace combina-
tion meter printed
circuit. <Ref. to
IDI-15, DISAS-
SEMBLY, Combi-
nation Meter
Assembly.>

Repair harness or
connector.

Step

Value

Yes

No

IM-14

IMMOBILIZER (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE FOR IMMOBILIZER INDICATOR LIGHT

2. CHECK KEY SWITCH CIRCUIT

WIRING DIAGRAM:

IM-00051

4

B141

B74

F2

B100

IMMOBILIZER

CONTROL

MODULE

KEY WARNING
SWITCH

BATTERY

2
1

M/B No. 6

L

L

R

R

16

: LHD MODEL

: RHD MODEL

L

R

B74

1
2

1
2

B141

1 2 3

4 5

6 7 8 9 10 11 12

F2

3 4

1 2

8 9 10 11

12 13 14 15 16 17 18 19 20 21 22 23 24

5 6

7

IM-15

IMMOBILIZER (DIAGNOSTICS)

DIAGNOSTIC PROCEDURE FOR IMMOBILIZER INDICATOR LIGHT

Step

Value

Yes

No

1

CHECK POWER SUPPLY CIRCUIT.
1) Disconnect harness connector from key

warning switch.

2) Measure voltage between key warning

switch harness connector terminal and
chassis ground.

Connector & terminal

(B74) No. 2 (+) — Chassis ground (

−−−−

):

Does the measured value exceed the spec-
ified value?

10 V

Go to step 2.

Check harness for
open or short
between key warn-
ing switch and
fuse.

2

CHECK KEY SWITCH.
1) Insert the ignition key to the ignition switch.

(OFF or ACC position)

2) Measure the resistance between key warn-

ing switch connector terminals.

Terminal

No. 1 — No. 2:

Is the measured value less than the speci-
fied value?

1

Ω

Go to step 3.

Replace key warn-
ing switch.

3

CHECK KEY SWITCH.
1) Remove the ignition key from the ignition

switch.

2) Measure the resistance between key warn-

ing switch connector terminals.

Terminal

No. 1 — No. 2:

Does the measured value exceed the spec-
ified value?

1 M

Ω

Go to step 4.

Replace key warn-
ing switch.

4

CHECK HARNESS BETWEEN KEY SWITCH
AND IMM ECM.
1) Disconnect harness connector from key

warning switch.

2) Disconnect harness connector from IMM

ECM.

3) Measure resistance between key warning

switch harness connector terminal and IMM
ECM harness connector terminal.

Connector & terminal

(B74) No. 1 — (B141) No. 4:

Is the measured value less than the speci-
fied value?

10

Ω

Replace IMM ECM
<Ref. to SL-36,
Immobilizer Con-
trol Module.> and
then replace all
ignition keys
(including the tran-
sponder). Then
perform teaching
operation. Refer to
teaching opera-
tion manual (Pub.
No. S0820GZ).

Repair harness
between key warn-
ing switch and
IMM ECM.