Subaru Legacy 2003 Service Manual page 22

DIAGNOSTIC PROCEDURE WITH TROUBLE CODE (DTC)
IMMOBILIZER (DIAGNOSTICS)
1 CHECK POWER SUPPLY CIRCUIT OF IMM
ECM.
1) Turn ignition switch OFF.
2) Disconnect harness connector from IMM
ECM.
3) 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?
2 CHECK POWER SUPPLY CIRCUIT OF IMM
ECM.
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?
3 CHECK GROUND CIRCUIT OF IMM ECM.
1) Turn ignition switch OFF.
2) Measure resistance between IMM ECM
harness connector terminal and chassis
ground.
Connector & terminal
(B141) No. 2, No.3 — Chassis ground:
Is the measured value less than the speci-
fied value?
4 CHECK HARNESS BETWEEN IMM ECM
AND ECM.
1) Disconnect harness connector from ECM
and IMM ECM.
2) Measure resistance between IMM ECM
harness connector terminal and ECM har-
ness connector terminal.
Connector & terminal
H4 non-TURBO without OBD model
(B141) No. 1 — (B135) No. 22:
H4 Non-TURBO with OBD model
(B141) No. 1 — (B137) No. 18:
H6 and H4 TURBO models
(B141) No. 1 — (B135) No. 5:
Is the measured value less than the speci-
fied value?
Step Value
10 V
10 V
10 Ω
10 Ω
IM-20
Yes
Go to step 2. Check harness for
open or short
between IMM
ECM and fuse.
Go to step 3. Check harness for
open or short
between IMM
ECM and ignition
switch.
Go to step 4. Repair open circuit
of IMM ECM
ground circuit.
Go to step 5. Repair open circuit
of harness
between IMM
ECM and ECM.
No