Yamaha 2004 YP400 Service Manual page 402

3. When the main switch is turned to "ON", the immobilizer system indicator light flashes.
• Check if a metal object or other immobilizer system keys are placed near the immobilizer unit. If
so, remove the object or keys, and then check the condition again.
Turn the main switch to "ON" with
another registered standard key and
check the immobilizer system indicator
light. The indicator light goes on for
about 1 second, then goes off.
Turn the main switch to "ON" with the
code re-registering key and check the
immobilizer system indicator light.
Check if a malfunction code is dis-
played.
Immobilizer unit or ECU malfunction
Check the signal lead (yellow/blue)
between the immobilizer unit and ECU
connector.
Replace the immobilizer unit.
IMMOBILIZER SYSTEM
Malfunction
Malfunction
Not displayed
Malfunction
Correct
Correct
First standard key (transponder) is
defective.
Second standard
Correct
key (transpon-
der) is defective.
Displayed
Read the malfunction code and check
the corresponding part.
Refer to "SELF-DIAGNOSIS MAL-
FUNCTION CODES".
Yellow/blue lead is disconnected or
short-circuited. Repair or replace the
circuit.
8 - 58
– +
ELEC
Re-register
the stan-
dard key.
Malfunc-
tion
Replace the
standard
key.