Yamaha YZ450F Owner's Service Manual page 297

8. Check the ignition system wire har-
ness.
Refer to "CIRCUIT DIAGRAM" on
page 8-2.
OK 
Replace the ECU.
The launch control indicator light fail to blink.
TIP
Before troubleshooting, remove the following part(s):
1. Seat
2. Air scoop (left)
1. Check the launch control switch
coupler connections.
OK 
2. Check the neutral switch coupler
connections.
OK 
3. Check the launch control switch.
Refer to "CHECKING THE
SWITCHES" on page 8-38.
OK 
4. Check the neutral switch.
Refer to "CHECKING THE NEU-
TRAL SWITCH" on page 8-46.
OK 
5. Check the fuel ignition system wire
harness.
Refer to "CIRCUIT DIAGRAM" on
page 8-2.
OK 
Replace the ECU.
NG 
Repair or replace the wire harness.
NG 
Reconnect.
NG 
Reconnect.
NG 
Replace the launch control switch.
NG 
Replace the neutral switch.
NG 
Repair or replace the wire harness.
8-5
IGNITION SYSTEM