Yamaha YP400T Service Manual page 362

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
Ch Dg Y
L
1
• 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?
YES
This circuit is OK.
EAS00790
3. The tail/brake light fails to come on.
1. Tail/brake light LEDs
• Check the tail/brake light LEDs.
• Are the tail/brake light LEDs OK?
YES
R/W
R/G G
Y/L B/L Gy B
2
NO
The wiring circuit
from the main switch
to the meter assem-
bly coupler is faulty
and must be
repaired.
NO
Replace the tail/
brake light assembly.
8 - 31
LIGHTING SYSTEM
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?
YES
This circuit is OK.
EAS00791
4. The front turn signal/position lights fail to
come on.
1. Front turn signal/position light bulb and
socket
• Check the front turn signal/position light
bulb and socket for continuity.
Refer to "CHECKING THE BULBS AND
BULB SOCKETS".
• Are the front turn signal/position light bulb
and socket OK?
YES
– +
ELEC
1
L Y G/Y Br
B B
2
NO
The wiring circuit
from the main switch
to the tail/brake light
coupler is faulty and
must be repaired.
NO
Replace the front
turn signal/position
light bulb, socket or
both.