2003 Yamaha YFM400FAR Kodiak Factory Service Manual, Page 336Get this manual

LIGHTING SYSTEM EB805021

2.If the taillight fails to come on: 1.Bulb and bulb socket
NO CONTINUITY

Check the bulb and bulb socket for continuityReplace the bulb andor bulb socketCONTINUITY

2.Voltage

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives