Yamaha 2004 YP400, Service Manual, Page: 387 / 417

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ELEC
SIGNALING SYSTEM
EAS00803
5. The engine oil change indicator fails to
come on.
YES
NO
EAS00806
6. The speedometer fails to operate.
YES
NO
1. Engine oil change indicator bulb and
socket
• Check the engine oil change indicator bulb
and socket for continuity.
Refer to “CHECKING THE BULBS AND
BULB SOCKETS”
• Are the engine oil change indicator bulb
and socket OK?
Replace the meter
assembly. Replace the engine
oil change indicator
bulb, socket or both.
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
→
blue
2
• Set the main switch to “ON”.
• Elevate the front wheel and slowly rotate
it.
• Measure the voltage (DC 5 V) of white and
blue. With each full rotation of the front
wheel, the voltage reading should cycle
from 0.6 V to 4.8 V to 0.6 V to 4.8 V.
• Does the voltage reading cycle correctly?
Replace the speed
sensor.