2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 341Get this manual
COOLING SYSTEM EBS01085 EBS01044
TROUBLESHOOTING The radiator fan motor fails to turnCheck: 1fuse 2battery 3main switch 4radiator fan motor 5circuit breaker (fan motor) 6thermo switch 7wiring connections (the entire cooling system) NOTE: Before troubleshooting, remove the following part(s): 1seat 2fuel tank cover 3side covers (left and right) 4front fender Troubleshoot with the following special tool(s)2Battery Check the condition of the batteryRefer to "CHECKING AND CHARGING THE BATTERY" in chapter 3Minimum open-circuit voltage 12.8 or more at 20 (68 F) Is the battery OK? YES NO Clean the battery terminals Recharge or replace the batteryEBS01041