Yamaha YZF-R1P Service Manual page 416

2. Voltage
• Connect the pocket tester (DC 20 V) to the
horn connector at the horn terminal as shown.
Positive tester probe → pink 1
Negative tester probe → ground
• Set the main switch to "ON".
• Push the horn switch.
• Measure the voltage (DC 12 V) of pink at
the horn terminal.
• Is the voltage within specification?
YES
3. Horn
• Disconnect the black connector at the horn
terminal.
• Connect a jumper lead 1 to the horn ter-
minal and ground the jumper lead.
• Set the main switch to "ON".
• Push the horn switch.
• Does the horn sound?
NO
Replace the horn.
SIGNALING SYSTEM
NO
The wiring circuit from
the main switch to the
horn connector is faulty
and must be repaired.
YES
The horn is OK.
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EAS00797
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. 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.
Positive tester probe → yellow 1
Negative tester probe → black 2
• 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 tail/brake light coupler (wire har-
ness side).
• Is the voltage within specification?
– +
ELEC
NO
Replace the tail/
brake light bulb,
socket or both.
NO
Replace the brake
light switch.