On the 650, the auto-on headlight relay started with the '78 model. The '78 was also the last year to have a headlight on-off switch on the right handlebar control. It was eliminated in '79 and on all later models. But, the '78 switch was severely hampered by that auto-on relay. It only worked with the key on and the engine not running. Once you started the motor, that safety auto-on relay kicked in and turned the headlight on, regardless of what position the on-off switch was in. Rather silly set-up in my eyes, lol, so I "fixed" it.