Yamaha YFM660FS Grizzly 4x4 Supplementary Service Manual page 458

8.If the differential gear lock indicator light LED
fails to come on:
1.Differential gear lock indicator light
Check the LED of the differential gear lock
G
indicator light.
Refer to "CHECKING THE LEDs".
2.Four-wheel drive switch
Refer to "CHECKING THE SWITCH".
3.Voltage
Connect the pocket tester (DC 20 V) to the
G
bulb socket lead.
Tester (+) lead → Black/Red terminal
Tester (–) lead → Frame ground
Turn the main switch to "ON".
G
Check the voltage (12 V).
G
This circuit is not faulty.
CONTINUITY
CONTINUITY
MEETS
SPECIFICATION
9 - 44
SIGNAL SYSTEM
NO CONTINUITY
Replace the meter assembly.
NO CONTINUITY
Replace the four-wheel drive switch.
OUT OF SPECIFICATION
The wiring circuit from the main switch to the
bulb socket connector is faulty, repair it.
– +
ELEC