2004 Official factory service manual for Yamaha YFZ450S ATV Quad., Page 321Get this manual
ELECTRIC STARTING SYSTEM EBS01054 EBS01042
6Starter relay Disconnect the starter relay coupler from the wire harness Connect the pocket tester1) and battery (12 V) to the starter relay as shownPositive battery terminal blueblack Negative battery terminal yellowblack Positive tester probe red Negative tester probe black 4
8Engine stop switch Check the engine stop switch for continuityRefer to "CHECKING THE SWITCHES" Is the engine stop switch OK? YES NO Replace the handlebar switchEBS01046