2002 Yamaha YFM660 Grizzly factory service and repair manual, Page 380Get this manual
SIGNAL SYSTEM CHECKING THE SIGNAL SYSTEM 1.If the brake light fails to come on: 1.Bulb and bulb socket
Check the bulb and bulb socket for continuityCONTINUITY
NO CONTINUITY
Replace the bulb andor bulb socket
2.Brake light switches Refer to "CHECKING THE SWITCH"CONTINUITY
NO CONTINUITY