Yamaha YXR70FX Service Manual page 473

2. Wiring
• Check the wiring circuit from the fuel pump
to ECU (brown/white) and fuel pump to
meter assembly (orange/black).
• Is the wiring circuit properly connect and
without defects?
YES
3. Voltage
• Connect the pocket tester (DC 20 V) to the
meter assembly coupler as shown.
Positive tester probe → brown/yellow 1
Negative tester probe → black/white 2
Y/L Br/Y B/W
O/B R/W
O/B R/W
Y/L Br/Y B/W
1 2
• Set the main switch to "ON".
• Measure the voltage (12 V) of brown/yel-
low 1 and black/white 2 at the meter
assembly coupler.
• Is the voltage within specification?
YES
Replace the meter
assembly.
SIGNALING SYSTEM
NO
Properly connect or
repair the wiring cir-
cuit.
NO
The wiring circuit
from the main switch
to the meter assem-
bly coupler is faulty
and must be
repaired.
9 - 43
8. The speedometer fails to come on.
1. Speed sensor
• Connect the pocket tester (DC 20 V) to the
speed sensor coupler (wire harness side)
as shown.
Positive tester probe → white 1
Negative tester probe → black/blue 2
W
• Turn the main switch to "ON".
• Elevate the rear wheels and slowly rotate
them.
• Measure the voltage of white and black/
blue. With each full rotation of the rear
wheels, the voltage reading should cycle
from 0.6 V to 4.8 V to 0.6 V to 4.8 V.
• Is the speed sensor OK?
YES
2. Wiring
• Check the wiring circuit from the speed
sensor to ECU and ECU to meter assem-
bly (yellow/blue).
• Is the wiring circuit properly connect and
without defects?
YES
– +
ELEC
1
L Y / L W
L
B / L B /
2
NO
Replace the speed
sensor.
NO
Properly connect or
repair the wiring cir-
cuit.