Yamaha YZ450F 2021 - Checking the Coolant Temperature Sensor

ELECTRICAL COMPONENTS
8-51
a. Set the digital tachometer to the ignition
coil.
b. Connect the digital circuit tester (DCV) to
the rectifier/regulator coupler.
c. Start the engine and let it run at about
5000 r/min.
d. Measure the output voltage.
EAM30303
CHECKING THE COOLANT TEMPERATURE
SENSOR
1. Remove:
• Coolant temperature sensor
WARNING
EWA14130
• Handle the coolant temperature sensor
with special care.
• Never subject the coolant temperature sen-
sor to strong shocks. If the coolant temper-
ature sensor is dropped, replace it.
2. Check:
• Coolant temperature sensor resistance
Out of specification  Replace.
a. Connect the digital circuit tester () to the
coolant temperature sensor.
b. Immerse the coolant temperature sensor
in a container filled with coolant.
TIP
Make sure the coolant temperature sensor ter-
minals do not get wet.
c. Place a thermometer in the coolant.
d. Slowly heat the coolant, and then let it cool
to the specified temperature indicated in
the table.
e. Check the coolant temperature sensor for
continuity at the temperatures indicated in
the table.
Regulated voltage (DC)
14.0–14.8 V
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with tachom-
eter
YU-A1927
• Positive tester probe 
Red “1”
• Negative tester probe 
Black “2”
B
WW
R
2 1
Coolant temperature sensor re-
sistance
2513–2777  at 20 C (2513–
2777  at 68 F)
Coolant temperature sensor re-
sistance
210–221  at 100 C (210–221 
at 212 F)
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with tachom-
eter
YU-A1927
• Positive tester probe 
Green/White “1”
• Negative tester probe 
Black/Blue “2”
1 2
G/W B/L
B/LG/W