Yamaha YP400T, YP400V, YP400W Service Manual page 370

2. Brake light switches
• Check the brake light switches for continu-
ity.
Refer to "CHECKING THE SWITCHES".
• Is the brake light switch OK?
YES
3. Voltage
• Connect the pocket tester (DC 20 V) to the
tail/brake light coupler (wire harness side)
as shown.
Positive tester probe → green/yellow 1
Negative tester probe → black 2
• Set the main switch to "ON".
• Pull in the brake levers.
• Measure the voltage (DC 12 V) of green/
yellow 1 on the tail/brake light coupler
(wire harness side).
• Is the voltage within specification?
YES
This circuit is OK.
NO
Replace the brake
light switch(s).
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.
SIGNALING SYSTEM
EAS00799
3. The turn signal light, turn signal indicator
light or both fail to blink.
1. Turn signal light bulb and socket
• Check the turn signal light bulb and socket
for continuity.
Refer to "CHECKING THE BULBS AND
BULB SOCKETS"
• Are the turn signal light bulb and socket
OK?
2. Turn signal indicator light bulb and socket
• Check the turn signal indicator light bulb
and socket for continuity.
Refer to "CHECKING THE BULBS AND
BULB SOCKETS"
• Are the turn signal indicator light bulb and
socket OK?
3. Turn signal switch
• Check the turn signal switch for continuity.
Refer to "CHECKING THE SWITCHES".
• Is the turn signal switch OK?
8 - 39
ELEC
YES
Replace the turn sig-
nal light bulb, socket
or both.
YES
Replace the turn sig-
nal indicator
bulb, socket or both.
YES
Replace the left han-
dlebar switch.
– +
NO
NO
light
NO