2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 319Get this manual
ELECTRIC STARTING SYSTEM EBS01050 EBS01044
TROUBLESHOOTING The starter motor fails to turnCheck: 1fuse 2battery 3starter motor 4starting circuit cut-off relay 5starting circuit cut-off relay (diode) 6starter relay 7main switch 8engine stop switch 9neutral switch 10.clutch switch 11.start switch 12.wiring connections (of the entire starting 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 batteryEBS01051