Yamaha YFM7FGPW Service Manual page 438

3. Voltage
• Connect the pocket tester (DC 20 V) to the
headlight couplers as shown.
È When the light switch is set to "LO"
É When the light switch is set to "HI"
Headlight coupler (wire harness side)
Headlight
Positive tester probe →
Negative tester probe → black 3
È
1
DC20V
Y
B
É
• Set the main switch to "ON".
• Set the light switch to "LO" or "HI".
• Measure the voltage (DC 12 V) of yellow
1 or green 2 on the headlight coupler
(wire harness side).
• Is the voltage within specification?
YES
This circuit is OK.
2. The taillight fails to come on.
1. Taillight bulb and socket
• Check the taillight bulb and socket for con-
tinuity.
Refer to "CHECKING THE BULBS AND
BULB SOCKETS".
• Are the taillight bulb and socket OK?
YES
yellow 1 or green 2
2
G
G Y
B
3
NO
The wiring circuit
from the main switch
to the headlight cou-
pler is faulty and
must be repaired.
NO
Replace the taillight
bulb, socket or both.
9 - 33
LIGHTING SYSTEM
2. Voltage
• Connect the pocket tester (DC 20 V) to the
tail/brake light connectors as shown.
Tail/brake light connectors (wire harness
side)
Positive tester probe → blue 1
Negative tester probe → black 2
• Set the main switch to "ON".
• Set the light switch to "LO" or "HI".
• Measure the voltage (DC 12 V) of blue 1
on the tail/brake light connectors (wire har-
ness side).
• Is the voltage within specification?
YES
This circuit is OK.
– +
ELEC
NO
The wiring circuit
from the main switch
to the tail/brake light
connectors are faulty
and must be
repaired.