Checking The Lean Angle Sensor; Checking The Starter Motor Operation; Checking The Stator Coil; Checking The Rectifier/Regulator - Yamaha YZ250FM 2021 Owner's Service Manual

b. Measure the crankshaft position sensor
resistance.
EAM30298

CHECKING THE LEAN ANGLE SENSOR

1. Check:
• Mounted condition of ECU
Improperly mounted  Remount.
TIP
• The lean angle sensor is built into the ECU.
• The lean angle sensor stops the engine in case
of a turnover.
• To ensure that the lean angle sensor operates
correctly, do not change the installed condition
of the ECU.
EAM30299
CHECKING THE STARTER MOTOR
OPERATION
1. Check:
• Starter motor operation
Does not operate  Perform the electric
starting system troubleshooting, starting with
step (4).
Refer to "TROUBLESHOOTING" on page
8-7.
a. Connect the positive battery terminal "1"
and starter motor lead "2" with a jumper
lead "3".
EWA13810
WARNING
• A wire that is used as a jumper lead must
have at least the same capacity of the bat-
tery lead, otherwise the jumper lead may
burn.
• This check is likely to produce sparks,
therefore, make sure no flammable gas or
fluid is in the vicinity.
1 2
Gy B
8-48
ELECTRICAL COMPONENTS
b. Check the starter motor operation.
EAM30300

CHECKING THE STATOR COIL

1. Disconnect:
• Stator coil assembly coupler
(from the wire harness)
2. Check:
• Stator coil assembly resistance
Out of specification  Replace.
Stator coil resistance
0.512–0.768 
a. Connect the digital circuit tester () to the
stator coil assembly coupler.
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with tachom-
eter
YU-A1927
• Positive tester probe 
White "1"
• Negative tester probe 
White "2"
b. Measure the stator coil assembly resis-
tance.
EAM30301

CHECKING THE RECTIFIER/REGULATOR

1. Check:
• Rectifier/regulator output voltage
Out of specification  Replace.
1 2