Yamaha YBR250 2007 Service Manual page 344

2. The brake light fails to come on.
1. Brake light bulb and socket.
• Check the brake light bulb and socket for
continuity.
Refer to "CHECKING THE BULBS AND
BULB SOCKETS"
• Are the brake light bulb and socket OK?
YES
2. Brake light switches
• Check the brake light switches for
continuity.
Refer to "CHECKING THE SWITCHES".
• Is the brake light switch OK?
YES
SIGNALING SYSTEM
NO
Replace the brake
light bulb, socket
or both.
NO
Replace the brake
light switch.
7-34
3. Voltage
• Connect the pocket tester (DC 20 V) to
the brake light coupler (wire harness side)
as shown.
Positive tester probe --> yellow 1
Negative tester probe --> black 2
Y L
• Set the main switch to "ON".
• Pull in the brake lever or push down on the
brake pedal.
• Measure the voltage (DC 12 V) of yellow
1 on the brake light coupler (wire
harness).
• Is the voltage within specification?
YES
The circuit is OK.
ELEC
1
Ch
Y
L
B Dg
1
NO
The wiring circuit
from the main switch
to the brake light
coupler is faulty and
must be repaired.