Yamaha 2005 BT1100 Supplementary Service Manual page 103

4. Voltage
• Connect the pocket tester (DC 20 V) to the
horn connecter at the black terminal as
shown.
Tester positive probe
Tester negative probe
• Set the main switch to "ON".
• Measure the voltage (12 V) of Black 1 at the
horn terminal.
• Is the voltage within specification?
YES
Repair or replace the
horn.
EAS00797
2. A tail/brake light fails to come on.
1. Tail/brake light bulb and socket
• Check the tail/brake light bulb and socket for
continuity.
Refer to "CHECKING THE BULBS AND
BULB SOCKETS".
• Are the tail/brake light bulb and socket OK?
YES
¡
Black 1
¡
Ground
NO
Replace the horn.
NO
Replace the tail/
brake lightbulb,
socket or both.
SIGNALING SYSTEM
2. Brake light switches
• Check the brake light switches for continuity.
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.
Tester positive probe
Tester negative probe
• Set the main switch to "ON".
• Pull in the brake lever or push down on the
brake pedal.
• Measure the voltage (12 V) of Yellow at the
tail/brake light coupler (wire harness side).
• Is the voltage within specification?
YES
This circuit is OK.
95
ELEC
NO
Replace the brake
light switch.
¡
Green/Yellow 1
¡
Black 2
NO
The wiring circuit
from the main switch
to the tail/brake light
coupler is faulty and
must be repaired.