Yamaha YZ 2017 Series Owner's Service Manual page 309

8. Check the lean angle sensor.
Refer to "CHECKING THE LEAN
ANGLE SENSOR" on page 8-70.
OK 
9. Check the entire ignition system's
wiring.
Refer to "CIRCUIT DIAGRAM" on
page 8-2.
OK 
Replace the ECU.
NG 
Replace the lean angle sensor.
NG 
Properly connect or repair the ignition sys-
tem's wiring.
8-5
IGNITION SYSTEM