Subaru Impreza 2003 Service Manual page 3298

DIAGNOSTICS CHART WITH DIAGNOSTIC TROUBLE CODE (DTC)
IMMOBILIZER (DIAGNOSTICS)
Step
1 CHECK POWER SUPPLY CIRCUIT OF IMM
ECM.
1)Turn the ignition switch to OFF.
2)Disconnect the harness connector from IMM
ECM.
3)Measure the voltage between IMM ECM har-
ness connector terminal and chassis ground.
Connector & terminal
(B141) No. 10, No.11 (+) — Chassis
ground ( − − − − ):
2 CHECK POWER SUPPLY CIRCUIT OF IMM
ECM.
1)Turn the ignition switch to ON. (Engine
OFF.)
2)Measure the voltage between IMM ECM har-
ness connector terminal and chassis ground.
Connector & terminal
(B141) No. 12 (+) — Chassis ground ( − − − − ):
3 CHECK GROUND CIRCUIT OF IMM ECM.
1)Turn the ignition switch to OFF.
2)Measure the resistance between IMM ECM
harness connector terminal and chassis
ground.
Connector & terminal
(B141) No. 2, No.3 — Chassis ground:
4 CHECK HARNESS BETWEEN IMM ECM
AND ECM.
1)Disconnect the harness connector from ECM
and IMM ECM.
2)Measure the resistance between IMM ECM
harness connector terminal and ECM harness
connector terminal.
Connector & terminal
LHD SOHC model
(B141) No. 1 — (B137) No. 17:
RHD SOHC model with OBD
(B141) No. 1 — (B137) No. 18:
RHD SOHC model without OBD
(B141) No. 1 — (B135) No. 22:
LHD turbo model
(B141) No. 1 — (B135) No. 14:
RHD turbo model
(B141) No. 1 — (B135) No. 5:
5 CHECK HARNESS BETWEEN IMM ECM
AND ECM.
Measure the resistance between IMM ECM
harness connector terminal and ECM harness
connector terminal.
Connector & terminal
LHD SOHC model
(B141) No. 6 — (B137) No. 18:
RHD SOHC model with OBD
(B141) No. 6 — (B137) No. 17:
RHD SOHC model without OBD
(B141) No. 6 — (B135) No. 23:
LHD turbo model
(B141) No. 6 — (B135) No. 5:
RHD turbo model
(B141) No. 6 — (B135) No. 14:
Check
Is the voltage more than 10 V? Go to step 2.
Is the voltage more than 10 V? Go to step 3.
Is the resistance less than 10
Ω?
Is the resistance less than 10
Ω?
Is the resistance less than 10
Ω?
IM-20
Yes
Check the harness
for open or short
between IMM
ECM and fuse.
Check the harness
for open or short
between IMM
ECM and ignition
switch.
Go to step 4. Repair the open
circuit of IMM ECM
ground circuit.
Go to step 5. Repair the open
circuit of harness
between IMM
ECM and ECM.
Go to step 6. Repair the open
circuit of harness
between IMM
ECM and ECM.
No