2004-2005 660 Yamaha Rhino Factory Service Manual, Page 387Get this manual
SIGNALING SYSTEM CHECKING THE SIGNAL SYSTEM 1If the brake lights fail to come on: 1Bulb and bulb socket Check the bulb and bulb socket for continuityCONTINUITY 2Brake light switch Refer to "CHECKING THE SWITCH"CONTINUITY NO CONTINUITY
Replace the bulb andor bulb socketNO CONTINUITY