Checking The Speed Sensor; Checking The Fuel Sender; Checking The Resistor - Yamaha WR450F 2021 Owner's Service Manual

• 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.
EAM30358

CHECKING THE SPEED SENSOR

1. Check:
• Speed sensor output voltage
Out of specification  Replace.
Output voltage reading cycle
0.6 V to 4.8 V to 0.6 V to 4.8 V
a. Connect the test harness– speed sensor
5TJ (3P) to the speed sensor coupler and
wire harness.
b. Connect the digital circuit tester (DC) to
the test harness– speed sensor 5TJ (3P).
Digital circuit tester (CD732)
90890-03243
Model 88 Multimeter with tachom-
eter
YU-A1927
Test harness– speed sensor 5TJ
(3P)
90890-03228
Test harness– speed sensor 5TJ
(3P)
YU-03228
• Positive tester probe 
Black/Blue "1"
• Negative tester probe 
White/Blue "2"
B R
2 1
8-68
ELECTRICAL COMPONENTS
2 1
W/L L B/L
c. Push the start switch.
d. Elevate the front wheel and slowly turn it.
e. Measure the voltage (DC 5 V) of white and
black/white. With the front wheel slowly ro-
tating, voltage alternates between 0 V and
5 V.
EAM30359

CHECKING THE FUEL SENDER

1. Disconnect:
• Starter motor lead
(from the starter relay)
2. Connect:
• Fuel pump coupler
3. Push the start switch.
4. Check:
• Fuel level warning light
Out of specification  Replace the fuel
pump.
Fuel pump is atmosphere "A"
 Fuel level warning light comes on
Fuel pump is soaked in fuel "B"
 Fuel level warning light goes off
EAM30360

CHECKING THE RESISTOR

1. Disconnect:
• Resistor coupler
(from the wire harness)
2. Check:
• Resistor resistance
Out of specification  Replace the resistor.