Yamaha YZ450FN 2022 Owner's Service Manual page 286

2. Check the mode switch.
Refer to "CHECKING THE
SWITCHES" on page 8-43.
OK
3. Check the ignition system wire har-
ness.
Refer to "CIRCUIT DIAGRAM" on
page 8-1.
OK
Replace the ECU.
Replace the mode switch.
NG
Repair or replace the wire harness.
NG
8-5
IGNITION SYSTEM