Yamaha YP400T Service Manual page 369

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
L
B
• 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.
SIGNALING SYSTEM
NO
Replace the brake
light switch(s).
1
Y G/Y Br
B
2
NO
The wiring circuit
from the main switch
to the tail/brake light
coupler is faulty and
must be repaired.
8 - 38
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?
YES
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?
YES
3. Turn signal switch
• Check the turn signal switch for continuity.
Refer to "CHECKING THE SWITCHES".
• Is the turn signal switch OK?
YES
– +
ELEC
NO
Replace the turn sig-
nal light bulb, socket
or both.
NO
Replace the turn sig-
nal indicator light
bulb, socket or both.
NO
Replace the left han-
dlebar switch.