Yamaha 2004 YP400, Service Manual, Page: 375 / 417

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ELEC
LIGHTING SYSTEM
EAS00789
2. The meter light fails to come on.
YES
NO
YES NO
EAS00790
3. The tail/brake light fails to come on.
YES
NO
YES NO
1. Meter light bulb and socket
• Check the meter light bulb and socket for
continuity.
Refer to “CHECKING THE BULBS AND
BULB SOCKETS”
• Are the meter light bulb and socket OK?
Replace the meter
light bulb, socket or
both.
2. Voltage
• Connect the pocket tester (DC 20 V) to the
meter assembly coupler (wire harness
side) as shown.
Positive tester probe
→
blue
1
Negative tester probe
→
black
2
• Set the main switch to “ON”.
• Measure the voltage (DC 12 V) of blue
1
on the meter assembly coupler (wire har-
ness side).
• Is the voltage within specification?
This circuit is OK. The wiring circuit
from the main switch
to the meter assem-
bly coupler is faulty
and must be
repaired.
G / L L Y / L B / L Gy B
Ch Dg Y R / W R / G G
2 1
1. Tail/brake light LEDs
• Check the tail/brake light LEDs.
• Are the tail/brake light LEDs OK?
Replace the tail/
brake light assembly.
2. Voltage
• Connect the pocket tester (DC 20 V) to the
tail/brake light coupler (wire harness side)
as shown.
Positive tester probe
→
brown
1
Negative tester probe
→
black
2
• Set the main switch to “ON”.
• Measure the voltage (DC 12 V) of brown
1
on the tail/brake light coupler (wire har-
ness side).
• Is the voltage within specification?
This circuit is OK. The wiring circuit
from the main switch
to the tail/brake light
coupler is faulty and
must be repaired.
L Y
B
G / Y Br
B
1
2