2001 Yamaha YFM660 Raptor Factory Service Manual, Page 313Get this manual
SIGNAL SYSTEM 3.If the reverse indicator light fails to come on: 1.Bulb and bulb socket
NO CONTINUITY
Check the bulb and bulb socket for continuityCONTINUITY Replace the bulb andor bulb socket
2.Reverse switch Refer to "CHECKING THE SWITCH"CONTINUITY
NO CONTINUITY