Yamaha XT660R S Service Manual page 418

EAS00790
2. The 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
2. Voltage
• Connect the pocket tester (DC 20 V) to the
tail/brake light coupler (wire harness end)
as shown.
Positive tester probe → blue/red 1
Negative tester probe → black 2
• Set the main switch to "ON".
• Measure the voltage (DC 12 V) of blue/red
1 at the tail/brake light coupler (wire har-
ness end).
• Is the voltage within specification?
YES
This circuit is OK.
NO
Replace the tail/
brake light bulb,
socket or both.
2
B B
L
L/R
Y Y
1
NO
The wiring circuit
from the main switch
to the tail/brake light
coupler is faulty and
must be repaired.
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LIGHTING SYSTEM
EAS00791
3. The auxiliary light fails to come on.
1. Auxiliary light bulb and socket
• Check the auxiliary light bulb and socket
for continuity.
Refer to "CHECKING THE BULBS AND
BULB SOCKETS".
• Are the auxiliary light bulb and socket OK?
2. Voltage
• Connect the pocket tester (DC 20 V) to the
auxiliary light coupler (wire harness end)
as shown.
Positive tester probe → blue/red 1
Negative tester probe → black 2
• Set the main switch to "ON".
• Measure the voltage (DC 12 V) of blue/red
1 at the auxiliary light connectors (wire
harness end).
• Is the voltage within specification?
This circuit is OK.
8 - 35
ELEC
YES
Replace the auxiliary
light bulb, socket or
both.
1
L/R L/R
B B
2
YES
The wiring
from the main switch
to the auxiliary light
coupler is faulty and
must be repaired.
– +
NO
NO
circuit