heres a weird one. My 1971 FLH shuts off when I turn the ignition to the lights ON .?

If I want to run with light on I have to start it with the lights on. The motor will also die if I switch the ignition to just run from running with the lights on. I can of course simply hit the starter button AFTER switching to OFF and then back to tun. I can hear the only cuircuit breaker on the bike reset as I do this. Already replaced the ignition switch. all the wiring looks OK. This bike is kick and electric start and wired like a chopper. It has a starter relay and one overload breaker. Havent looked yet at headlight wiring. Everything under the dash looks correct. Anyone have a thought? if you arent familiar with OLD bikes dont waste my time with your guess! I have already removed the neutral safety so she fires up in gear and replaced the ignition switch and the starter relay and the breaker.