Subaru Impreza 2003 Service Manual page 3291

DIAGNOSTICS CHART FOR IMMOBILIZER INDICATOR LIGHT
Step
1 CHECK POWER SUPPLY CIRCUIT.
1)Disconnect the harness connector from key
warning switch.
2)Turn the ignition switch to ACC or LOCK
position (The key inserted).
3)Measure the voltage between key warning
switch harness connector terminal and chassis
ground.
Connector & terminal
(B74) No. 2 (+) — Chassis ground ( − − − − ):
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.
Connector & terminal
No. 1 — No. 2:
3 CHECK KEY SWITCH.
1)Remove the ignition key from the ignition
switch.
2)Measure the resistance between key warn-
ing switch connector terminals.
Connector & terminal
No. 1 — No. 2:
4 CHECK HARNESS BETWEEN KEY SWITCH
AND IMM ECM.
1)Disconnect the harness connector from key
warning switch.
2)Disconnect the harness connector from IMM
ECM.
3)Measure the resistance between key warn-
ing switch harness connector terminal and
IMM ECM harness connector terminal.
Connector & terminal
(B74) No. 1 — (B141) No. 4:
Check
Is the voltage more than 10 V? Go to step 2.
Is the resistance less than 1
Ω?
Is the resistance more than 1
MΩ?
Is the resistance less than 10
Ω?
IM-13
IMMOBILIZER (DIAGNOSTICS)
Yes
Check the harness
for open or short
between key warn-
ing switch and
fuse.
Go to step 3. Replace the key
warning switch.
Go to step 4. Replace the key
warning switch.
Replace the IMM Repair the har-
ECM <Ref. to SL- ness between key
39, Immobilizer warning switch
Control Module.> and IMM ECM.
and then replace
all ignition keys
(including the tran-
sponder). Then
perform teaching
operation. Refer to
teaching opera-
tion manual (Pub.
No. S0820GZ).
No