Yamaha 2004 YP400, Service Manual, Page: 374 / 417

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ELEC
LIGHTING SYSTEM
EAS00788
CHECKING THE LIGHTING SYSTEM
1. The headlights and the high beam indicator
light fail to come on.
YES NO
YES
NO
YES
NO
1. Headlight bulb and socket
• Check the headlight bulb and socket for
continuity.
Refer to “CHECKING THE BULBS AND
BULB SOCKETS”
• Are the headlight bulb and socket OK?
Replace the head-
light bulb, socket or
both.
2. High beam indicator light bulb and socket
• Check the high beam indicator light bulb
and socket for continuity.
Refer to “CHECKING THE BULBS AND
BULB SOCKETS”.
• Is the high beam indicator light bulb and
socket OK?
Replace the high
beam indicator light
bulb, socket or both.
3. Voltage
• Connect the pocket tester (DC 20 V) to the
headlight and meter assembly couplers as
shown.
È
When the dimmer switch is set to “ ”
É
When the dimmer switch is set to “ ”
Headlight
Positive tester probe
→
yellow
1
or green
2
Negative tester probe
→
black
3
Headlight coupler
High beam indicator light
Positive tester probe
→
yellow
4
Negative tester probe
→
black
5
Meter assembly coupler
• Set the main switch to “ON”.
• Start the engine.
• Set the dimmer switch to “
” or “ ”.
• Measure the voltage (DC 12 V) of yellow
1
(green
2
) on the headlight coupler and
yellow
4
on the meter assembly coupler
(wire harness side).
• Is the voltage within specification?
This circuit is OK. The wiring circuit
from the main switch
to the headlight cou-
pler or meter assem-
bly coupler is faulty
and must be
repaired.
DC 20V
+
B Y
G
1
È
É
2
3
G / L L Y / L B / L Gy B
Ch Dg Y R / W R / G G
5 4