Yamaha YZ450FX 2019 Owner's Service Manual page 299

9. Check the stator coil.
Refer to "CHECKING THE STA-
TOR COIL" on page 8-64.
OK
10.Check the ignition system wire har-
ness.
Refer to "CIRCUIT DIAGRAM" on
page 8-1.
OK
Replace the ECU.
The mode switch to blink.
TIP
Before troubleshooting, remove the following part(s):
1. Seat
2. Air scoop (left)
1. Check the mode switch coupler
connections.
OK
2. Check the mode switch.
Refer to "CHECKING THE
SWITCHES" on page 8-55.
OK
3. Check the ignition system wire har-
ness.
Refer to "CIRCUIT DIAGRAM" on
page 8-1.
OK
Replace the ECU.
Replace the stator coil.
NG
Repair or replace the wire harness.
NG
Reconnect.
NG
Replace the mode switch.
NG
Repair or replace the wire harness.
NG
8-4
IGNITION SYSTEM