Yamaha 2004 YP400, Service Manual, Page: 376 / 417

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ELEC
LIGHTING SYSTEM
EAS00791
4. The auxiliary lights fail to come on.
YES
NO
YES
NO
EAS00792
5. The license plate light fails to come on.
YES
NO
YES
NO
1. Auxiliary light bulb and socket
• Check the auxiliary light bulb and socket
for continuity.
Refer to “CHECKING THE BULBS AND
BULB SOCKETS”
• Are the auxiliary light bulb and socket OK?
Replace the auxiliary
light bulb, socket or
both.
2. Voltage
• Connect the pocket tester (DC 20 V) to the
front turn signal light assembly coupler
(wire harness side) as shown.
È
Front turn signal light assembly (left)
É
Front turn signal light assembly (right)
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 front turn signal light assembly cou-
pler (wire harness side).
• Is the voltage within specification?
This circuit is OK. The wiring circuit
from the main switch
to the front turn sig-
nal light assembly
coupler is faulty and
must be repaired.
B L Ch
B L Ch
B L Dg
B L Dg
1 2 1 2
È É
1. License plate light bulb and socket
• Check the license plate light bulb and
socket for continuity.
Refer to “CHECKING THE BULBS AND
BULB SOCKETS”
• Are the license plate light bulb and socket
OK?
Replace the license
plate light bulb,
socket or both.
2. Voltage
• Connect the pocket tester (DC 20 V) to the
taillight assembly 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 taillight assembly coupler (wire
harness side).
• Is the voltage within specification?
This circuit is OK. The wiring circuit
from the main switch
to the taillight assem-
bly coupler is faulty
and must be
repaired.
L / R
Dg
B
Ch
Br
Dg
B
Ch
1 2