2002 Yamaha YFM660 Grizzly factory service and repair manual, Page 386Get this manual
SIGNAL SYSTEM
7.If the coolant temperature indicator light does not come on when the main switch to "ON", or if the coolant temperature indicator light does not come on when the temperature is high (more than 107113 (224.6235.4 F)): 1.Coolant temperature indicator light LED
NO CONTINUITY
Check the LED of the coolant indicator lightRefer to "CHECKING THE LEDs"CONTINUITY
Replace the meter assembly
2.Thermo switch 1