Yamaha YQ50 Service Manual page 170

2. Voltage
• Connect the pocket tester (AC20V) to the
meter light coupler.
Pocket tester (+) lead © Blue / Red Q
Pocket tester (-) lead © Black W
• Set the main switch to "ON".
• Start the engine.
• Check the voltage (12V) between the head-
light coupler leads "Blue / Red" and "Black".
Circuit is in good condition.
3. The tail light does not work.
1. Bulb and socket
• Check the bulb and socket for continuity.
2. Voltage
• Connect the pocket tester (AC20V) to the
taillight coupler.
Pocket tester (+) lead © Blue / Black Q
Pocket tester (-) lead © Black W
• Set the main switch to "ON".
• Start the engine.
• Check the voltage (12V) between the head-
light coupler leads "Blue / Red" and "Black".
Circuit is in good condition.
LIGHTING SYSTEM
MEETS
SPECIFICATION
CONTINUITY
MEETS
SPECIFICATION
8-20
OUT OF SPECIFICATION
There is a defect in the wire harness between
the main switch and the meter light coupler
© Repair.
NO CONTINUITY
Replace bulb or socket.
LR
LR
GY
GY
B
B
OUT OF SPECIFICATION
There is a defect in the wire harness between
the main switch and the taillight coupler ©
Repair.
ELEC
B
B
G
B G
RY RY
RY RY
LR LR
LR LR
LR LR