2000 Yamaha YFM400FWA(M) Factory Service workshop Manual, Page 327Get this manual
ELECTRIC STARTING SYSTEM
5.Starter relay
C0NTINUITY
Remove the starter relay from the wire harnessConnect the pocket tester1) and the battery (12 V) to the starter relay terminals
Battery (+) terminal BlueWhite terminal Battery () terminal BlueBlack terminal Tester (+) lead Red terminal Tester () lead Black terminal 4
NO CONTINUITY
Check the starter relay for continuityCONTINUITY
Replace the starter relay