Checking The Ecu; Checking The Stator Coil; Checking The Rectifier/Regulator - Yamaha YZ450F(E) 2014 Owner's Service Manual

CHECKING THE ECU

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 condi-
tion of the ECU.

CHECKING THE STATOR COIL

EAS1SL1340
1. Disconnect:
• Stator coil coupler
(from the wire harness)
2. Check:
• Stator coil resistance
Out of specification  Replace.
Stator coil resistance
0.624–0.936 
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Connect the pocket tester ( 1) to the sta-
tor coil coupler.
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe 
White "1"
• Negative tester probe 
White "2"
b. Measure the stator coil resistance.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS1SL1341
1 2
8-43
ELECTRICAL COMPONENTS

CHECKING THE RECTIFIER/REGULATOR

1. Check:
• Rectifier/regulator output voltage
Out of specification  Replace.
Output voltage
14 V or more at 5000 r/min
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Set the digital tachometer to the ignition coil.
Digital tachometer
90890-06760
YU-39951-B
b. Connect the pocket tester (20 VDC) to the
rectifier/regulator coupler.
Pocket tester
90890-03112
Analog pocket tester
YU-03112-C
• Positive tester probe 
Red "1"
• Negative tester probe 
Black "2"
W W
c. Start the engine and let it run at about 5000
r/min.
d. Measure the output voltage.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAS1SL1342
B R
2 1