Headlamp not working

Diagnosis no headlamp on hi or low beam 1981 yamaha xj750 seca when install a jumper from red/yellow tracer to blue wire at relay everything works fine so relay not being triggered swapped relays didn't change. Can someone tell me where white/blue tracer wire gets energized from ?

 

The relay gets energized by one leg of the alternator (white wire), so either you have an open in that wire / diode block or the charging system is not working. The same wire from the alternator that energizes the relay also initializes the Atari system when the bike starts.

Check for 14.5 +/- .3 V at the battery when the bike is revved above about 2500 RPM to verify charging system is working. If the charging system is working, then look for the open wire

 

Thank you that is very helpful and diagram helps because charging fine and atari working correctly so has to be diode block or broken wire. Tomorrow guess will try and locate diode block first

 

Don't know if it applies to your problem. I have a 1981 Seca 550. Headlamp connector had power when unplugged from the headlamp, but went away when plugged in. I eventually replaced the left handlebar switch and it's fine now. Go figure.... (I hate electrical..)